Provided by: perltidy_20210717-1_all 
NAME
perltidy - a perl script indenter and reformatter
SYNOPSIS
perltidy [ options ] file1 file2 file3 ...
(output goes to file1.tdy, file2.tdy, file3.tdy, ...)
perltidy [ options ] file1 -o outfile
perltidy [ options ] file1 -st >outfile
perltidy [ options ] <infile >outfile
DESCRIPTION
Perltidy reads a perl script and writes an indented, reformatted script.
Many users will find enough information in "EXAMPLES" to get started. New users may benefit from the
short tutorial which can be found at http://perltidy.sourceforge.net/tutorial.html
A convenient aid to systematically defining a set of style parameters can be found at
http://perltidy.sourceforge.net/stylekey.html
Perltidy can produce output on either of two modes, depending on the existence of an -html flag. Without
this flag, the output is passed through a formatter. The default formatting tries to follow the
recommendations in perlstyle(1), but it can be controlled in detail with numerous input parameters, which
are described in "FORMATTING OPTIONS".
When the -html flag is given, the output is passed through an HTML formatter which is described in "HTML
OPTIONS".
EXAMPLES
perltidy somefile.pl
This will produce a file somefile.pl.tdy containing the script reformatted using the default options,
which approximate the style suggested in perlstyle(1). The source file somefile.pl is unchanged.
perltidy *.pl
Execute perltidy on all .pl files in the current directory with the default options. The output will be
in files with an appended .tdy extension. For any file with an error, there will be a file with
extension .ERR.
perltidy -b file1.pl file2.pl
Modify file1.pl and file2.pl in place, and backup the originals to file1.pl.bak and file2.pl.bak. If
file1.pl.bak and/or file2.pl.bak already exist, they will be overwritten.
perltidy -b -bext='/' file1.pl file2.pl
Same as the previous example except that the backup files file1.pl.bak and file2.pl.bak will be deleted
if there are no errors.
perltidy -gnu somefile.pl
Execute perltidy on file somefile.pl with a style which approximates the GNU Coding Standards for C
programs. The output will be somefile.pl.tdy.
perltidy -i=3 somefile.pl
Execute perltidy on file somefile.pl, with 3 columns for each level of indentation (-i=3) instead of the
default 4 columns. There will not be any tabs in the reformatted script, except for any which already
exist in comments, pod documents, quotes, and here documents. Output will be somefile.pl.tdy.
perltidy -i=3 -et=8 somefile.pl
Same as the previous example, except that leading whitespace will be entabbed with one tab character per
8 spaces.
perltidy -ce -l=72 somefile.pl
Execute perltidy on file somefile.pl with all defaults except use "cuddled elses" (-ce) and a maximum
line length of 72 columns (-l=72) instead of the default 80 columns.
perltidy -g somefile.pl
Execute perltidy on file somefile.pl and save a log file somefile.pl.LOG which shows the nesting of
braces, parentheses, and square brackets at the start of every line.
perltidy -html somefile.pl
This will produce a file somefile.pl.html containing the script with html markup. The output file will
contain an embedded style sheet in the <HEAD> section which may be edited to change the appearance.
perltidy -html -css=mystyle.css somefile.pl
This will produce a file somefile.pl.html containing the script with html markup. This output file will
contain a link to a separate style sheet file mystyle.css. If the file mystyle.css does not exist, it
will be created. If it exists, it will not be overwritten.
perltidy -html -pre somefile.pl
Write an html snippet with only the PRE section to somefile.pl.html. This is useful when code snippets
are being formatted for inclusion in a larger web page. No style sheet will be written in this case.
perltidy -html -ss >mystyle.css
Write a style sheet to mystyle.css and exit.
perltidy -html -frm mymodule.pm
Write html with a frame holding a table of contents and the source code. The output files will be
mymodule.pm.html (the frame), mymodule.pm.toc.html (the table of contents), and mymodule.pm.src.html (the
source code).
OPTIONS - OVERVIEW
The entire command line is scanned for options, and they are processed before any files are processed.
As a result, it does not matter whether flags are before or after any filenames. However, the relative
order of parameters is important, with later parameters overriding the values of earlier parameters.
For each parameter, there is a long name and a short name. The short names are convenient for keyboard
input, while the long names are self-documenting and therefore useful in scripts. It is customary to use
two leading dashes for long names, but one may be used.
Most parameters which serve as on/off flags can be negated with a leading "n" (for the short name) or a
leading "no" or "no-" (for the long name). For example, the flag to outdent long quotes is -olq or
--outdent-long-quotes. The flag to skip this is -nolq or --nooutdent-long-quotes or
--no-outdent-long-quotes.
Options may not be bundled together. In other words, options -q and -g may NOT be entered as -qg.
Option names may be terminated early as long as they are uniquely identified. For example, instead of
--dump-token-types, it would be sufficient to enter --dump-tok, or even --dump-t, to uniquely identify
this command.
I/O control
The following parameters concern the files which are read and written.
-h, --help
Show summary of usage and exit.
-o=filename, --outfile=filename
Name of the output file (only if a single input file is being processed). If no output file is
specified, and output is not redirected to the standard output (see -st), the output will go to
filename.tdy. [Note: - does not redirect to standard output. Use -st instead.]
-st, --standard-output
Perltidy must be able to operate on an arbitrarily large number of files in a single run, with each
output being directed to a different output file. Obviously this would conflict with outputting to
the single standard output device, so a special flag, -st, is required to request outputting to the
standard output. For example,
perltidy somefile.pl -st >somefile.new.pl
This option may only be used if there is just a single input file. The default is -nst or
--nostandard-output.
-se, --standard-error-output
If perltidy detects an error when processing file somefile.pl, its default behavior is to write error
messages to file somefile.pl.ERR. Use -se to cause all error messages to be sent to the standard
error output stream instead. This directive may be negated with -nse. Thus, you may place -se in a
.perltidyrc and override it when desired with -nse on the command line.
-oext=ext, --output-file-extension=ext
Change the extension of the output file to be ext instead of the default tdy (or html in case the
--html option is used). See "Specifying File Extensions".
-opath=path, --output-path=path
When perltidy creates a filename for an output file, by default it merely appends an extension to the
path and basename of the input file. This parameter causes the path to be changed to path instead.
The path should end in a valid path separator character, but perltidy will try to add one if it is
missing.
For example
perltidy somefile.pl -opath=/tmp/
will produce /tmp/somefile.pl.tdy. Otherwise, somefile.pl.tdy will appear in whatever directory
contains somefile.pl.
If the path contains spaces, it should be placed in quotes.
This parameter will be ignored if output is being directed to standard output, or if it is being
specified explicitly with the -o=s parameter.
-b, --backup-and-modify-in-place
Modify the input file or files in-place and save the original with the extension .bak. Any existing
.bak file will be deleted. See next item for changing the default backup extension, and for
eliminating the backup file altogether.
A -b flag will be ignored if input is from standard input or goes to standard output, or if the -html
flag is set.
In particular, if you want to use both the -b flag and the -pbp (--perl-best-practices) flag, then
you must put a -nst flag after the -pbp flag because it contains a -st flag as one of its components,
which means that output will go to the standard output stream.
-bext=ext, --backup-file-extension=ext
This parameter serves two purposes: (1) to change the extension of the backup file to be something
other than the default .bak, and (2) to indicate that no backup file should be saved.
To change the default extension to something other than .bak see "Specifying File Extensions".
A backup file of the source is always written, but you can request that it be deleted at the end of
processing if there were no errors. This is risky unless the source code is being maintained with a
source code control system.
To indicate that the backup should be deleted include one forward slash, /, in the extension. If any
text remains after the slash is removed it will be used to define the backup file extension (which is
always created and only deleted if there were no errors).
Here are some examples:
Parameter Extension Backup File Treatment
<-bext=bak> F<.bak> Keep (same as the default behavior)
<-bext='/'> F<.bak> Delete if no errors
<-bext='/backup'> F<.backup> Delete if no errors
<-bext='original/'> F<.original> Delete if no errors
-w, --warning-output
Setting -w causes any non-critical warning messages to be reported as errors. These include messages
about possible pod problems, possibly bad starting indentation level, and cautions about indirect
object usage. The default, -nw or --nowarning-output, is not to include these warnings.
-q, --quiet
Deactivate error messages (for running under an editor).
For example, if you use a vi-style editor, such as vim, you may execute perltidy as a filter from
within the editor using something like
:n1,n2!perltidy -q
where "n1,n2" represents the selected text. Without the -q flag, any error message may mess up your
screen, so be prepared to use your "undo" key.
-log, --logfile
Save the .LOG file, which has many useful diagnostics. Perltidy always creates a .LOG file, but by
default it is deleted unless a program bug is suspected. Setting the -log flag forces the log file
to be saved.
-g=n, --logfile-gap=n
Set maximum interval between input code lines in the logfile. This purpose of this flag is to assist
in debugging nesting errors. The value of "n" is optional. If you set the flag -g without the value
of "n", it will be taken to be 1, meaning that every line will be written to the log file. This can
be helpful if you are looking for a brace, paren, or bracket nesting error.
Setting -g also causes the logfile to be saved, so it is not necessary to also include -log.
If no -g flag is given, a value of 50 will be used, meaning that at least every 50th line will be
recorded in the logfile. This helps prevent excessively long log files.
Setting a negative value of "n" is the same as not setting -g at all.
-npro --noprofile
Ignore any .perltidyrc command file. Normally, perltidy looks first in your current directory for a
.perltidyrc file of parameters. (The format is described below). If it finds one, it applies those
options to the initial default values, and then it applies any that have been defined on the command
line. If no .perltidyrc file is found, it looks for one in your home directory.
If you set the -npro flag, perltidy will not look for this file.
-pro=filename or --profile=filename
To simplify testing and switching .perltidyrc files, this command may be used to specify a
configuration file which will override the default name of .perltidyrc. There must not be a space on
either side of the '=' sign. For example, the line
perltidy -pro=testcfg
would cause file testcfg to be used instead of the default .perltidyrc.
A pathname begins with three dots, e.g. ".../.perltidyrc", indicates that the file should be searched
for starting in the current directory and working upwards. This makes it easier to have multiple
projects each with their own .perltidyrc in their root directories.
-opt, --show-options
Write a list of all options used to the .LOG file. Please see --dump-options for a simpler way to do
this.
-f, --force-read-binary
Force perltidy to process binary files. To avoid producing excessive error messages, perltidy skips
files identified by the system as non-text. However, valid perl scripts containing binary data may
sometimes be identified as non-text, and this flag forces perltidy to process them.
-ast, --assert-tidy
This flag asserts that the input and output code streams are identical, or in other words that the
input code is already 'tidy' according to the formatting parameters. If this is not the case, an
error message noting this is produced. This error message will cause the process to return a non-
zero exit code. The test for this is made by comparing an MD5 hash value for the input and output
code streams. This flag has no other effect on the functioning of perltidy. This might be useful for
certain code maintenance operations. Note: you will not see this message if you have error messages
turned off with the -quiet flag.
-asu, --assert-untidy
This flag asserts that the input and output code streams are different, or in other words that the
input code is 'untidy' according to the formatting parameters. If this is not the case, an error
message noting this is produced. This flag has no other effect on the functioning of perltidy.
-sal=s, --sub-alias-list=s
This flag causes one or more words to be treated the same as if they were the keyword 'sub'. The
string s contains one or more alias words, separated by spaces or commas.
For example,
perltidy -sal='method fun _sub M4'
will cause the perltidy to treate the words 'method', 'fun', '_sub' and 'M4' to be treated the same
as if they were 'sub'. Note that if the alias words are separated by spaces then the string of words
should be placed in quotes.
Note that several other parameters accept a list of keywords, including 'sub' (see "Specifying Block
Types"). You do not need to include any sub aliases in these lists. Just include keyword 'sub' if
you wish, and all aliases are automatically included.
FORMATTING OPTIONS
Basic Options
--notidy
This flag disables all formatting and causes the input to be copied unchanged to the output except
for possible changes in line ending characters and any pre- and post-filters. This can be useful in
conjunction with a hierarchical set of .perltidyrc files to avoid unwanted code tidying. See also
"Skipping Selected Sections of Code" for a way to avoid tidying specific sections of code.
-i=n, --indent-columns=n
Use n columns per indentation level (default n=4).
-l=n, --maximum-line-length=n
The default maximum line length is n=80 characters. Perltidy will try to find line break points to
keep lines below this length. However, long quotes and side comments may cause lines to exceed this
length.
The default length of 80 comes from the past when this was the standard CRT screen width. Many
programmers prefer to increase this to something like 120.
Setting -l=0 is equivalent to setting -l=(a very large number). But this is not recommended because,
for example, a very long list will be formatted in a single long line.
-vmll, --variable-maximum-line-length
A problem arises using a fixed maximum line length with very deeply nested code and data structures
because eventually the amount of leading whitespace used for indicating indentation takes up most or
all of the available line width, leaving little or no space for the actual code or data. One
solution is to use a vary long line length. Another solution is to use the -vmll flag, which
basically tells perltidy to ignore leading whitespace when measuring the line length.
To be precise, when the -vmll parameter is set, the maximum line length of a line of code will be
M+L*I, where
M is the value of --maximum-line-length=M (-l=M), default 80,
I is the value of --indent-columns=I (-i=I), default 4,
L is the indentation level of the line of code
When this flag is set, the choice of breakpoints for a block of code should be essentially
independent of its nesting depth. However, the absolute line lengths, including leading whitespace,
can still be arbitrarily large. This problem can be avoided by including the next parameter.
The default is not to do this (-nvmll).
-wc=n, --whitespace-cycle=n
This flag also addresses problems with very deeply nested code and data structures. When the nesting
depth exceeds the value n the leading whitespace will be reduced and start at a depth of 1 again.
The result is that blocks of code will shift back to the left rather than moving arbitrarily far to
the right. This occurs cyclically to any depth.
For example if one level of indentation equals 4 spaces (-i=4, the default), and one uses -wc=15,
then if the leading whitespace on a line exceeds about 4*15=60 spaces it will be reduced back to
4*1=4 spaces and continue increasing from there. If the whitespace never exceeds this limit the
formatting remains unchanged.
The combination of -vmll and -wc=n provides a solution to the problem of displaying arbitrarily deep
data structures and code in a finite window, although -wc=n may of course be used without -vmll.
The default is not to use this, which can also be indicated using -wc=0.
Tabs
Using tab characters will almost certainly lead to future portability and maintenance problems, so
the default and recommendation is not to use them. For those who prefer tabs, however, there are two
different options.
Except for possibly introducing tab indentation characters, as outlined below, perltidy does not
introduce any tab characters into your file, and it removes any tabs from the code (unless requested
not to do so with -fws). If you have any tabs in your comments, quotes, or here-documents, they will
remain.
-et=n, --entab-leading-whitespace
This flag causes each n initial space characters to be replaced by one tab character.
The value of the integer n can be any value but can be coordinated with the number of spaces used
for intentation. For example, -et=4 -ci=4 -i=4 will produce one tab for each indentation level
and and one for each continuation indentation level. You may want to coordinate the value of n
with what your display software assumes for the spacing of a tab.
-t, --tabs
This flag causes one leading tab character to be inserted for each level of indentation. Certain
other features are incompatible with this option, and if these options are also given, then a
warning message will be issued and this flag will be unset. One example is the -lp option. This
flag is retained for backwards compatibility, but if you use tabs, the -et=n flag is recommended.
-dt=n, --default-tabsize=n
If the first line of code passed to perltidy contains leading tabs but no tab scheme is specified
for the output stream then perltidy must guess how many spaces correspond to each leading tab.
This number of spaces n corresponding to each leading tab of the input stream may be specified
with -dt=n. The default is n=8.
This flag has no effect if a tab scheme is specified for the output stream, because then the
input stream is assumed to use the same tab scheme and indentation spaces as for the output
stream (any other assumption would lead to unstable editing).
-xs, --extended-syntax
A problem with formatting Perl code is that some modules can introduce new syntax. This flag allows
perltidy to handle certain common extensions to the standard syntax without complaint.
For example, without this flag a structure such as the following would generate a syntax error and
the braces would not be balanced:
method deposit( Num $amount) {
$self->balance( $self->balance + $amount );
}
For one of the extensions, module Switch::Plain, colons are marked as labels. If you use this
module, you may want to also use the --nooutdent-labels flag to prevent lines such as 'default:' from
being outdented.
This flag is enabled by default but it can be deactivated with -nxs. Probably the only reason to
deactivate this flag is to generate more diagnostic messages when debugging a script.
For another method of handling extended syntax see the section "Skipping Selected Sections of Code".
-io, --indent-only
This flag is used to deactivate all whitespace and line break changes within non-blank lines of code.
When it is in effect, the only change to the script will be to the indentation and to the number of
blank lines. And any flags controlling whitespace and newlines will be ignored. You might want to
use this if you are perfectly happy with your whitespace and line breaks, and merely want perltidy to
handle the indentation. (This also speeds up perltidy by well over a factor of two, so it might be
useful when perltidy is merely being used to help find a brace error in a large script).
Setting this flag is equivalent to setting --freeze-newlines and --freeze-whitespace.
If you also want to keep your existing blank lines exactly as they are, you can add
--freeze-blank-lines.
With this option perltidy is still free to modify the indenting (and outdenting) of code and comments
as it normally would. If you also want to prevent long comment lines from being outdented, you can
add either -noll or -l=0.
Setting this flag will prevent perltidy from doing any special operations on closing side comments.
You may still delete all side comments however when this flag is in effect.
-enc=s, --character-encoding=s
This flag indicates the character encoding, if any, of the input data stream. Perltidy does not look
for the encoding directives in the soure stream, such as use utf8, and instead relies on this flag to
determine the encoding. (Note that perltidy often works on snippets of code rather than complete
files so it cannot rely on use utf8 directives).
The possible values for s are (1) the name of an encoding recognized by the Encode.pm module, (2)
none if no encoding is used, or (3) <guess> if perltidy should guess.
For example, the value utf8 causes the stream to be read and written as UTF-8. If the input stream
cannot be decoded with a specified encoding then processing is not done.
The value none causes the stream to be processed without special encoding assumptions. This is
appropriate for files which are written in single-byte character encodings such as latin-1.
The value guess tells perltidy to guess between either utf8 encoding or no encoding (meaning one
character per byte). The guess uses the Encode::Guess module and this restricted range of guesses
covers the most common cases. Testing showed that considering any greater number of encodings as
guess suspects is too risky.
The current default is guess.
The abbreviations -utf8 or -UTF8 are equivalent to -enc=utf8, and the abbreviation -guess is
equivalent to <-enc=guess>. So to process a file named file.pl which is encoded in UTF-8 you can
use:
perltidy -utf8 file.pl
or
perltidy -guess file.pl
To process a file in euc-jp you could use
perltidy -enc=euc-jp file.pl
A perltidy output file is unencoded if the input file is unencoded, and otherwise it is encoded as
utf8, even if the input encoding was not utf8.
-gcs, --use-unicode-gcstring
This flag controls whether or not perltidy may use module Unicode::GCString to obtain accurate
display widths of wide characters. The default is --nouse-unicode-gcstring.
If this flag is set, and text is encoded, perltidy will look for the module Unicode::GCString and, if
found, will use it to obtain character display widths. This can improve displayed vertical alignment
for files with wide characters. It is a nice feature but it is off by default to avoid conflicting
formatting when there are multiple developers. Perltidy installation does not require
Unicode::GCString, so users wanting to use this feature need set this flag and also to install
Unicode::GCString separately.
If this flag is set and perltidy does not find module Unicode::GCString, a warning message will be
produced and processing will continue but without the potential benefit provided by the module.
Also note that actual vertical alignment depends upon the fonts used by the text display software, so
vertical alignment may not be optimal even when Unicode::GCString is used.
-ole=s, --output-line-ending=s
where s="win", "dos", "unix", or "mac". This flag tells perltidy to output line endings for a
specific system. Normally, perltidy writes files with the line separator character of the host
system. The "win" and "dos" flags have an identical result.
-ple, --preserve-line-endings
This flag tells perltidy to write its output files with the same line endings as the input file, if
possible. It should work for dos, unix, and mac line endings. It will only work if perltidy input
comes from a filename (rather than stdin, for example). If perltidy has trouble determining the
input file line ending, it will revert to the default behavior of using the line ending of the host
system.
-atnl, --add-terminal-newline
This flag, which is enabled by default, allows perltidy to terminate the last line of the output
stream with a newline character, regardless of whether or not the input stream was terminated with a
newline character. If this flag is negated, with -natnl, then perltidy will add a terminal newline
to the the output stream only if the input stream is terminated with a newline.
Negating this flag may be useful for manipulating one-line scripts intended for use on a command
line.
-it=n, --iterations=n
This flag causes perltidy to do n complete iterations. The reason for this flag is that code
beautification is an iterative process and in some cases the output from perltidy can be different if
it is applied a second time. For most purposes the default of n=1 should be satisfactory. However
n=2 can be useful when a major style change is being made, or when code is being beautified on check-
in to a source code control system. It has been found to be extremely rare for the output to change
after 2 iterations. If a value n is greater than 2 is input then a convergence test will be used to
stop the iterations as soon as possible, almost always after 2 iterations. See the next item for a
simplified iteration control.
This flag has no effect when perltidy is used to generate html.
-conv, --converge
This flag is equivalent to -it=4 and is included to simplify iteration control. For all practical
purposes one either does or does not want to be sure that the output is converged, and there is no
penalty to using a large iteration limit since perltidy will check for convergence and stop iterating
as soon as possible. The default is -nconv (no convergence check). Using -conv will approximately
double run time since typically one extra iteration is required to verify convergence. No extra
iterations are required if no new line breaks are made, and two extra iterations are occasionally
needed when reformatting complex code structures, such as deeply nested ternary statements.
Code Indentation Control
-ci=n, --continuation-indentation=n
Continuation indentation is extra indentation spaces applied when a long line is broken. The default
is n=2, illustrated here:
my $level = # -ci=2
( $max_index_to_go >= 0 ) ? $levels_to_go[0] : $last_output_level;
The same example, with n=0, is a little harder to read:
my $level = # -ci=0
( $max_index_to_go >= 0 ) ? $levels_to_go[0] : $last_output_level;
The value given to -ci is also used by some commands when a small space is required. Examples are
commands for outdenting labels, -ola, and control keywords, -okw.
When default values are not used, it is recommended that either
(1) the value n given with -ci=n be no more than about one-half of the number of spaces assigned to a
full indentation level on the -i=n command, or
(2) the flag -extended-continuation-indentation is used (see next section).
-xci, --extended-continuation-indentation
This flag allows perltidy to use some improvements which have been made to its indentation model. One
of the things it does is "extend" continuation indentation deeper into structures, hence the name.
The improved indentation is particularly noticeable when the flags -ci=n and -i=n use the same value
of n. There are no significant disadvantages to using this flag, but to avoid disturbing existing
formatting the default is not to use it, -nxci.
Please see the section "-pbp, --perl-best-practices" for an example of how this flag can improve the
formatting of ternary statements. It can also improve indentation of some multi-line qw lists as
shown below.
# perltidy
foreach $color (
qw(
AntiqueWhite3 Bisque1 Bisque2 Bisque3 Bisque4
SlateBlue3 RoyalBlue1 SteelBlue2 DeepSkyBlue3
),
qw(
LightBlue1 DarkSlateGray1 Aquamarine2 DarkSeaGreen2
SeaGreen1 Yellow1 IndianRed1 IndianRed2 Tan1 Tan4
)
)
# perltidy -xci
foreach $color (
qw(
AntiqueWhite3 Bisque1 Bisque2 Bisque3 Bisque4
SlateBlue3 RoyalBlue1 SteelBlue2 DeepSkyBlue3
),
qw(
LightBlue1 DarkSlateGray1 Aquamarine2 DarkSeaGreen2
SeaGreen1 Yellow1 IndianRed1 IndianRed2 Tan1 Tan4
)
)
-sil=n --starting-indentation-level=n
By default, perltidy examines the input file and tries to determine the starting indentation level.
While it is often zero, it may not be zero for a code snippet being sent from an editing session.
To guess the starting indentation level perltidy simply assumes that indentation scheme used to
create the code snippet is the same as is being used for the current perltidy process. This is the
only sensible guess that can be made. It should be correct if this is true, but otherwise it
probably won't. For example, if the input script was written with -i=2 and the current peltidy flags
have -i=4, the wrong initial indentation will be guessed for a code snippet which has non-zero
initial indentation. Likewise, if an entabbing scheme is used in the input script and not in the
current process then the guessed indentation will be wrong.
If the default method does not work correctly, or you want to change the starting level, use -sil=n,
to force the starting level to be n.
List indentation using -lp, --line-up-parentheses
By default, perltidy indents lists with 4 spaces, or whatever value is specified with -i=n. Here is
a small list formatted in this way:
# perltidy (default)
@month_of_year = (
'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'
);
Use the -lp flag to add extra indentation to cause the data to begin past the opening parentheses of
a sub call or list, or opening square bracket of an anonymous array, or opening curly brace of an
anonymous hash. With this option, the above list would become:
# perltidy -lp
@month_of_year = (
'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'
);
If the available line length (see -l=n ) does not permit this much space, perltidy will use less.
For alternate placement of the closing paren, see the next section.
This option has no effect on code BLOCKS, such as if/then/else blocks, which always use whatever is
specified with -i=n.
In situations where perltidy does not have complete freedom to choose line breaks it may temporarily
revert to its default indentation method. This can occur for example if there are blank lines, block
comments, multi-line quotes, or side comments between the opening and closing parens, braces, or
brackets.
In addition, any parameter which significantly restricts the ability of perltidy to choose newlines
will conflict with -lp and will cause -lp to be deactivated. These include -io, -fnl, -nanl, and
-ndnl. The reason is that the -lp indentation style can require the careful coordination of an
arbitrary number of break points in hierarchical lists, and these flags may prevent that.
The -lp option may not be used together with the -t tabs option. It may, however, be used with the
-et=n tab method.
-lpxl=s, --line-up-parentheses-exclusion-list
This is an experimental parameter; the details might change as experience with it is gained.
The -lp indentation style works well for some types of coding but can produce very long lines when
variables have long names and/or containers are very deeply nested. The -lpxl=s flag is intended to
help mitigate this problem by providing control over the containers to which the -lp indentation
style is applied. The -lp flag by default is "greedy" and applies to as many containers as possible.
This flag specifies a list of things which should not be use -lp indentation.
This list is a string with space-separated items. Each item consists of up to three pieces of
information in this order: (1) an optional letter code (2) a required container type, and (3) an
optional numeric code.
The only required piece of information is a container type, which is one of '(', '[', or '{'. For
example the string
-lpxl='[ {'
means do NOT include use -lp formatting within square-bracets or braces. The only unspecified
container is '(', so this string means that only the contents within parens will use -lp indentation.
An optional numeric code may follow any of the container types to further refine the selection based
on container contents. The numeric codes are:
'0' or blank: no check on contents
'1' reject -lp unless the contents is a simple list without sublists
'2' reject -lp unless the contents is a simple list without sublists, without
code blocks, and without ternary operators
For example,
-lpxl = '[ { (2'
means only apply -lp to parenthesized lists which do not contain any sublists, code blocks or ternary
expressions.
A third optional item of information which can be given for parens is an alphanumeric letter which is
used to limit the selection further depending on the type of token immediately before the paren. The
possible letters are currently 'k', 'K', 'f', 'F', 'w', and 'W', with these meanings:
'k' matches if the previous nonblank token is a perl builtin keyword (such as 'if', 'while'),
'K' matches if 'k' does not, meaning that the previous token is not a keyword.
'f' matches if the previous token is a function other than a keyword.
'F' matches if 'f' does not.
'w' matches if either 'k' or 'f' match.
'W' matches if 'w' does not.
For example,
-lpxl = '[ { F(2'
means only apply -lp to parenthesized lists which follow a function call and which do not contain any
sublists, code blocks or ternary expressions. The logic of writing these codes is somewhat counter-
intuitive because they describe what is not getting the -lp indentation. So the 'F' indicates that
non-function calls are not getting -lp, or in other words that function calls are getting the -lp
indentation.
-cti=n, --closing-token-indentation
The -cti=n flag controls the indentation of a line beginning with a ")", "]", or a non-block "}".
Such a line receives:
-cti = 0 no extra indentation (default)
-cti = 1 extra indentation such that the closing token
aligns with its opening token.
-cti = 2 one extra indentation level if the line looks like:
); or ]; or };
-cti = 3 one extra indentation level always
The flags -cti=1 and -cti=2 work well with the -lp flag (previous section).
# perltidy -lp -cti=1
@month_of_year = (
'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'
);
# perltidy -lp -cti=2
@month_of_year = (
'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'
);
These flags are merely hints to the formatter and they may not always be followed. In particular, if
-lp is not being used, the indentation for cti=1 is constrained to be no more than one indentation
level.
If desired, this control can be applied independently to each of the closing container token types.
In fact, -cti=n is merely an abbreviation for -cpi=n -csbi=n -cbi=n, where: -cpi or
--closing-paren-indentation controls )'s, -csbi or --closing-square-bracket-indentation controls ]'s,
-cbi or --closing-brace-indentation controls non-block }'s.
-icp, --indent-closing-paren
The -icp flag is equivalent to -cti=2, described in the previous section. The -nicp flag is
equivalent -cti=0. They are included for backwards compatibility.
-icb, --indent-closing-brace
The -icb option gives one extra level of indentation to a brace which terminates a code block . For
example,
if ($task) {
yyy();
} # -icb
else {
zzz();
}
The default is not to do this, indicated by -nicb.
-nib, --non-indenting-braces
Normally, lines of code contained within a pair of block braces receive one additional level of
indentation. This flag, which is enabled by default, causes perltidy to look for opening block
braces which are followed by a special side comment. This special side comment is #<<< by default.
If found, the code between this opening brace and its corresponding closing brace will not be given
the normal extra indentation level. For example:
{ #<<< a closure to contain lexical vars
my $var; # this line does not get one level of indentation
...
}
# this line does not 'see' $var;
This can be useful, for example, when combining code from different files. Different sections of
code can be placed within braces to keep their lexical variables from being visible to the end of the
file. To keep the new braces from causing all of their contained code to be indented if you run
perltidy, and possibly introducing new line breaks in long lines, you can mark the opening braces
with this special side comment.
Only the opening brace needs to be marked, since perltidy knows where the closing brace is. Braces
contained within marked braces may also be marked as non-indenting.
If your code happens to have some opening braces followed by '#<<<', and you don't want this
behavior, you can use -nnib to deactivate it. To make it easy to remember, the default string is the
same as the string for starting a format-skipping section. There is no confusion because in that case
it is for a block comment rather than a side-comment.
The special side comment can be changed with the next parameter.
-nibp=s, --non-indenting-brace-prefix=s
The -nibp=string parameter may be used to change the marker for non-indenting braces. The default is
equivalent to -nibp='#<<<'. The string that you enter must begin with a # and should be in quotes as
necessary to get past the command shell of your system. This string is the leading text of a regex
pattern that is constructed by appending pre-pending a '^' and appending a'\s', so you must also
include backslashes for characters to be taken literally rather than as patterns.
For example, to match the side comment '#++', the parameter would be
-nibp='#\+\+'
-olq, --outdent-long-quotes
When -olq is set, lines which is a quoted string longer than the value maximum-line-length will have
their indentation removed to make them more readable. This is the default. To prevent such out-
denting, use -nolq or --nooutdent-long-lines.
-oll, --outdent-long-lines
This command is equivalent to --outdent-long-quotes and --outdent-long-comments, and it is included
for compatibility with previous versions of perltidy. The negation of this also works, -noll or
--nooutdent-long-lines, and is equivalent to setting -nolq and -nolc.
Outdenting Labels: -ola, --outdent-labels
This command will cause labels to be outdented by 2 spaces (or whatever -ci has been set to), if
possible. This is the default. For example:
my $i;
LOOP: while ( $i = <FOTOS> ) {
chomp($i);
next unless $i;
fixit($i);
}
Use -nola to not outdent labels.
Outdenting Keywords
-okw, --outdent-keywords
The command -okw will cause certain leading control keywords to be outdented by 2 spaces (or
whatever -ci has been set to), if possible. By default, these keywords are "redo", "next",
"last", "goto", and "return". The intention is to make these control keywords easier to see. To
change this list of keywords being outdented, see the next section.
For example, using "perltidy -okw" on the previous example gives:
my $i;
LOOP: while ( $i = <FOTOS> ) {
chomp($i);
next unless $i;
fixit($i);
}
The default is not to do this.
Specifying Outdented Keywords: -okwl=string, --outdent-keyword-list=string
This command can be used to change the keywords which are outdented with the -okw command. The
parameter string is a required list of perl keywords, which should be placed in quotes if there
are more than one. By itself, it does not cause any outdenting to occur, so the -okw command is
still required.
For example, the commands "-okwl="next last redo goto" -okw" will cause those four keywords to be
outdented. It is probably simplest to place any -okwl command in a .perltidyrc file.
Whitespace Control
Whitespace refers to the blank space between variables, operators, and other code tokens.
-fws, --freeze-whitespace
This flag causes your original whitespace to remain unchanged, and causes the rest of the whitespace
commands in this section, the Code Indentation section, and the Comment Control section to be
ignored.
Tightness of curly braces, parentheses, and square brackets
Here the term "tightness" will mean the closeness with which pairs of enclosing tokens, such as
parentheses, contain the quantities within. A numerical value of 0, 1, or 2 defines the tightness,
with 0 being least tight and 2 being most tight. Spaces within containers are always symmetric, so
if there is a space after a "(" then there will be a space before the corresponding ")".
The -pt=n or --paren-tightness=n parameter controls the space within parens. The example below shows
the effect of the three possible values, 0, 1, and 2:
if ( ( my $len_tab = length( $tabstr ) ) > 0 ) { # -pt=0
if ( ( my $len_tab = length($tabstr) ) > 0 ) { # -pt=1 (default)
if ((my $len_tab = length($tabstr)) > 0) { # -pt=2
When n is 0, there is always a space to the right of a '(' and to the left of a ')'. For n=2 there
is never a space. For n=1, the default, there is a space unless the quantity within the parens is a
single token, such as an identifier or quoted string.
Likewise, the parameter -sbt=n or --square-bracket-tightness=n controls the space within square
brackets, as illustrated below.
$width = $col[ $j + $k ] - $col[ $j ]; # -sbt=0
$width = $col[ $j + $k ] - $col[$j]; # -sbt=1 (default)
$width = $col[$j + $k] - $col[$j]; # -sbt=2
Curly braces which do not contain code blocks are controlled by the parameter -bt=n or
--brace-tightness=n.
$obj->{ $parsed_sql->{ 'table' }[0] }; # -bt=0
$obj->{ $parsed_sql->{'table'}[0] }; # -bt=1 (default)
$obj->{$parsed_sql->{'table'}[0]}; # -bt=2
And finally, curly braces which contain blocks of code are controlled by the parameter -bbt=n or
--block-brace-tightness=n as illustrated in the example below.
%bf = map { $_ => -M $_ } grep { /\.deb$/ } dirents '.'; # -bbt=0 (default)
%bf = map { $_ => -M $_ } grep {/\.deb$/} dirents '.'; # -bbt=1
%bf = map {$_ => -M $_} grep {/\.deb$/} dirents '.'; # -bbt=2
To simplify input in the case that all of the tightness flags have the same value <n>, the parameter
<-act=n> or --all-containers-tightness=n is an abbreviation for the combination <-pt=n -sbt=n -bt=n
-bbt=n>.
-tso, --tight-secret-operators
The flag -tso causes certain perl token sequences (secret operators) which might be considered to be
a single operator to be formatted "tightly" (without spaces). The operators currently modified by
this flag are:
0+ +0 ()x!! ~~<> ,=> =( )=
For example the sequence 0 +, which converts a string to a number, would be formatted without a
space: 0+ when the -tso flag is set. This flag is off by default.
-sts, --space-terminal-semicolon
Some programmers prefer a space before all terminal semicolons. The default is for no such space,
and is indicated with -nsts or --nospace-terminal-semicolon.
$i = 1 ; # -sts
$i = 1; # -nsts (default)
-sfs, --space-for-semicolon
Semicolons within for loops may sometimes be hard to see, particularly when commas are also present.
This option places spaces on both sides of these special semicolons, and is the default. Use -nsfs
or --nospace-for-semicolon to deactivate it.
for ( @a = @$ap, $u = shift @a ; @a ; $u = $v ) { # -sfs (default)
for ( @a = @$ap, $u = shift @a; @a; $u = $v ) { # -nsfs
-asc, --add-semicolons
Setting -asc allows perltidy to add any missing optional semicolon at the end of a line which is
followed by a closing curly brace on the next line. This is the default, and may be deactivated with
-nasc or --noadd-semicolons.
-dsm, --delete-semicolons
Setting -dsm allows perltidy to delete extra semicolons which are simply empty statements. This is
the default, and may be deactivated with -ndsm or --nodelete-semicolons. (Such semicolons are not
deleted, however, if they would promote a side comment to a block comment).
-aws, --add-whitespace
Setting this option allows perltidy to add certain whitespace to improve code readability. This is
the default. If you do not want any whitespace added, but are willing to have some whitespace
deleted, use -naws. (Use -fws to leave whitespace completely unchanged).
-dws, --delete-old-whitespace
Setting this option allows perltidy to remove some old whitespace between characters, if necessary.
This is the default. If you do not want any old whitespace removed, use -ndws or
--nodelete-old-whitespace.
Detailed whitespace controls around tokens
For those who want more detailed control over the whitespace around tokens, there are four parameters
which can directly modify the default whitespace rules built into perltidy for any token. They are:
-wls=s or --want-left-space=s,
-nwls=s or --nowant-left-space=s,
-wrs=s or --want-right-space=s,
-nwrs=s or --nowant-right-space=s.
These parameters are each followed by a quoted string, s, containing a list of token types. No more
than one of each of these parameters should be specified, because repeating a command-line parameter
always overwrites the previous one before perltidy ever sees it.
To illustrate how these are used, suppose it is desired that there be no space on either side of the
token types = + - / *. The following two parameters would specify this desire:
-nwls="= + - / *" -nwrs="= + - / *"
(Note that the token types are in quotes, and that they are separated by spaces). With these
modified whitespace rules, the following line of math:
$root = -$b + sqrt( $b * $b - 4. * $a * $c ) / ( 2. * $a );
becomes this:
$root=-$b+sqrt( $b*$b-4.*$a*$c )/( 2.*$a );
These parameters should be considered to be hints to perltidy rather than fixed rules, because
perltidy must try to resolve conflicts that arise between them and all of the other rules that it
uses. One conflict that can arise is if, between two tokens, the left token wants a space and the
right one doesn't. In this case, the token not wanting a space takes priority.
It is necessary to have a list of all token types in order to create this type of input. Such a list
can be obtained by the command --dump-token-types. Also try the -D flag on a short snippet of code
and look at the .DEBUG file to see the tokenization.
WARNING Be sure to put these tokens in quotes to avoid having them misinterpreted by your command
shell.
Note1: Perltidy does always follow whitespace controls
The various parameters controlling whitespace within a program are requests which perltidy follows as
well as possible, but there are a number of situations where changing whitespace could change program
behavior and is not done. Some of these are obvious; for example, we should not remove the space
between the two plus symbols in '$x+ +$y' to avoid creating a '++' operator. Some are more subtle and
involve the whitespace around bareword symbols and locations of possible filehandles. For example,
consider the problem of formatting the following subroutine:
sub print_div {
my ($x,$y)=@_;
print $x/$y;
}
Suppose the user requests that / signs have a space to the left but not to the right. Perltidy will
refuse to do this, but if this were done the result would be
sub print_div {
my ($x,$y)=@_;
print $x /$y;
}
If formatted in this way, the program will not run (at least with recent versions of perl) because
the $x is taken to be a filehandle and / is assumed to start a quote. In a complex program, there
might happen to be a / which terminates the multiline quote without a syntax error, allowing the
program to run, but not as intended.
Related issues arise with other binary operator symbols, such as + and -, and in older versions of
perl there could be problems with ternary operators. So to avoid changing program behavior, perltidy
has the simple rule that whitespace around possible filehandles is left unchanged. Likewise,
whitespace around barewords is left unchanged. The reason is that if the barewords are defined in
other modules, or in code that has not even been written yet, perltidy will not have seen their
prototypes and must treat them cautiously.
In perltidy this is implemented in the tokenizer by marking token following a print keyword as a
special type Z. When formatting is being done, whitespace following this token type is generally
left unchanged as a precaution against changing program behavior. This is excessively conservative
but simple and easy to implement. Keywords which are treated similarly to print include printf,
sort, exec, system. Changes in spacing around parameters following these keywords may have to be
made manually. For example, the space, or lack of space, after the parameter $foo in the following
line will be unchanged in formatting.
system($foo );
system($foo);
To find if a token is of type Z you can use perltidy -DEBUG. For the first line above the result is
1: system($foo );
1: kkkkkk{ZZZZb};
which shows that system is type k (keyword) and $foo is type Z.
Note2: Perltidy's whitespace rules are not perfect
Despite these precautions, it is still possible to introduce syntax errors with some asymmetric
whitespace rules, particularly when call parameters are not placed in containing parens or braces.
For example, the following two lines will be parsed by perl without a syntax error:
# original programming, syntax ok
my @newkeys = map $_-$nrecs+@data, @oldkeys;
# perltidy default, syntax ok
my @newkeys = map $_ - $nrecs + @data, @oldkeys;
But the following will give a syntax error:
# perltidy -nwrs='-'
my @newkeys = map $_ -$nrecs + @data, @oldkeys;
For another example, the following two lines will be parsed without syntax error:
# original programming, syntax ok
for my $severity ( reverse $SEVERITY_LOWEST+1 .. $SEVERITY_HIGHEST ) { ... }
# perltidy default, syntax ok
for my $severity ( reverse $SEVERITY_LOWEST + 1 .. $SEVERITY_HIGHEST ) { ... }
But the following will give a syntax error:
# perltidy -nwrs='+', syntax error:
for my $severity ( reverse $SEVERITY_LOWEST +1 .. $SEVERITY_HIGHEST ) { ... }
To avoid subtle parsing problems like this, it is best to avoid spacing a binary operator
asymetrically with a space on the left but not on the right.
Space between specific keywords and opening paren
When an opening paren follows a Perl keyword, no space is introduced after the keyword, unless it is
(by default) one of these:
my local our and or xor eq ne if else elsif until unless
while for foreach return switch case given when
These defaults can be modified with two commands:
-sak=s or --space-after-keyword=s adds keywords.
-nsak=s or --nospace-after-keyword=s removes keywords.
where s is a list of keywords (in quotes if necessary). For example,
my ( $a, $b, $c ) = @_; # default
my( $a, $b, $c ) = @_; # -nsak="my local our"
The abbreviation -nsak='*' is equivalent to including all of the keywords in the above list.
When both -nsak=s and -sak=s commands are included, the -nsak=s command is executed first. For
example, to have space after only the keywords (my, local, our) you could use -nsak="*" -sak="my
local our".
To put a space after all keywords, see the next item.
Space between all keywords and opening parens
When an opening paren follows a function or keyword, no space is introduced after the keyword except
for the keywords noted in the previous item. To always put a space between a function or keyword and
its opening paren, use the command:
-skp or --space-keyword-paren
You may also want to use the flag -sfp (next item) too.
Space between all function names and opening parens
When an opening paren follows a function the default and recommended formatting is not to introduce a
space. To cause a space to be introduced use:
-sfp or --space-function-paren
myfunc( $a, $b, $c ); # default
myfunc ( $a, $b, $c ); # -sfp
You will probably also want to use the flag -skp (previous item) too.
The reason this is not recommended is that spacing a function paren can make a program vulnerable to
parsing problems by Perl. For example, the following two-line program will run as written but will
have a syntax error if reformatted with -sfp:
if ( -e filename() ) { print "I'm here\n"; }
sub filename { return $0 }
In this particular case the syntax error can be removed if the line order is reversed, so that Perl
parses 'sub filename' first.
-fpva or --function-paren-vertical-alignment
A side-effect of using the -sfp flag is that the parens may become vertically aligned. For example,
# perltidy -sfp
myfun ( $aaa, $b, $cc );
mylongfun ( $a, $b, $c );
This is the default behavior. To prevent this alignment use -nfpva:
# perltidy -sfp -nfpva
myfun ( $aaa, $b, $cc );
mylongfun ( $a, $b, $c );
-spp=n or --space-prototype-paren=n
This flag can be used to control whether a function prototype is preceded by a space. For example,
the following prototype does not have a space.
sub usage();
This integer n may have the value 0, 1, or 2 as follows:
-spp=0 means no space before the paren
-spp=1 means follow the example of the source code [DEFAULT]
-spp=2 means always put a space before the paren
The default is -spp=1, meaning that a space will be used if and only if there is one in the source
code. Given the above line of code, the result of applying the different options would be:
sub usage(); # n=0 [no space]
sub usage(); # n=1 [default; follows input]
sub usage (); # n=2 [space]
-kpit=n or --keyword-paren-inner-tightness=n
The space inside of an opening paren, which itself follows a certain keyword, can be controlled by
this parameter. The space on the inside of the corresponding closing paren will be treated in the
same (balanced) manner. This parameter has precedence over any other paren spacing rules. The
values of n are as follows:
-kpit=0 means always put a space (not tight)
-kpit=1 means ignore this parameter [default]
-kpit=2 means never put a space (tight)
To illustrate, the following snippet is shown formatted in three ways:
if ( seek( DATA, 0, 0 ) ) { ... } # perltidy (default)
if (seek(DATA, 0, 0)) { ... } # perltidy -pt=2
if ( seek(DATA, 0, 0) ) { ... } # perltidy -pt=2 -kpit=0
In the second case the -pt=2 parameter makes all of the parens tight. In the third case the -kpit=0
flag causes the space within the 'if' parens to have a space, since 'if' is one of the keywords to
which the -kpit flag applies by default. The remaining parens are still tight because of the -pt=2
parameter.
The set of keywords to which this parameter applies are by default are:
if elsif unless while until for foreach
These can be changed with the parameter -kpitl=s described in the next section.
-kpitl=string or --keyword-paren-inner-tightness=string
This command can be used to change the keywords to which the the -kpit=n command applies. The
parameter string is a required list either keywords or functions, which should be placed in quotes if
there are more than one. By itself, this parameter does not cause any change in spacing, so the
-kpit=n command is still required.
For example, the commands "-kpitl="if else while" -kpit=2" will cause the just the spaces inside
parens following 'if', 'else', and 'while' keywords to follow the tightness value indicated by the
-kpit=2 flag.
-lop or --logical-padding
In the following example some extra space has been inserted on the second line between the two open
parens. This extra space is called "logical padding" and is intended to help align similar things
vertically in some logical or ternary expressions.
# perltidy [default formatting]
$same =
( ( $aP eq $bP )
&& ( $aS eq $bS )
&& ( $aT eq $bT )
&& ( $a->{'title'} eq $b->{'title'} )
&& ( $a->{'href'} eq $b->{'href'} ) );
Note that this is considered to be a different operation from "vertical alignment" because space at
just one line is being adjusted, whereas in "vertical alignment" the spaces at all lines are being
adjusted. So it sort of a local version of vertical alignment.
Here is an example involving a ternary operator:
# perltidy [default formatting]
$bits =
$top > 0xffff ? 32
: $top > 0xff ? 16
: $top > 1 ? 8
: 1;
This behavior is controlled with the flag --logical-padding, which is set 'on' by default. If it is
not desired it can be turned off using --nological-padding or -nlop. The above two examples become,
with -nlop:
# perltidy -nlop
$same =
( ( $aP eq $bP )
&& ( $aS eq $bS )
&& ( $aT eq $bT )
&& ( $a->{'title'} eq $b->{'title'} )
&& ( $a->{'href'} eq $b->{'href'} ) );
# perltidy -nlop
$bits =
$top > 0xffff ? 32
: $top > 0xff ? 16
: $top > 1 ? 8
: 1;
Trimming whitespace around "qw" quotes
-tqw or --trim-qw provide the default behavior of trimming spaces around multi-line "qw" quotes and
indenting them appropriately.
-ntqw or --notrim-qw cause leading and trailing whitespace around multi-line "qw" quotes to be left
unchanged. This option will not normally be necessary, but was added for testing purposes, because
in some versions of perl, trimming "qw" quotes changes the syntax tree.
-sbq=n or --space-backslash-quote=n
lines like
$str1=\"string1";
$str2=\'string2';
can confuse syntax highlighters unless a space is included between the backslash and the single or
double quotation mark.
this can be controlled with the value of n as follows:
-sbq=0 means no space between the backslash and quote
-sbq=1 means follow the example of the source code
-sbq=2 means always put a space between the backslash and quote
The default is -sbq=1, meaning that a space will be used if there is one in the source code.
Trimming trailing whitespace from lines of POD
-trp or --trim-pod will remove trailing whitespace from lines of POD. The default is not to do this.
Comment Controls
Perltidy has a number of ways to control the appearance of both block comments and side comments. The
term block comment here refers to a full-line comment, whereas side comment will refer to a comment which
appears on a line to the right of some code.
-ibc, --indent-block-comments
Block comments normally look best when they are indented to the same level as the code which follows
them. This is the default behavior, but you may use -nibc to keep block comments left-justified.
Here is an example:
# this comment is indented (-ibc, default)
if ($task) { yyy(); }
The alternative is -nibc:
# this comment is not indented (-nibc)
if ($task) { yyy(); }
See also the next item, -isbc, as well as -sbc, for other ways to have some indented and some
outdented block comments.
-isbc, --indent-spaced-block-comments
If there is no leading space on the line, then the comment will not be indented, and otherwise it may
be.
If both -ibc and -isbc are set, then -isbc takes priority.
-olc, --outdent-long-comments
When -olc is set, lines which are full-line (block) comments longer than the value maximum-line-
length will have their indentation removed. This is the default; use -nolc to prevent outdenting.
-msc=n, --minimum-space-to-comment=n
Side comments look best when lined up several spaces to the right of code. Perltidy will try to keep
comments at least n spaces to the right. The default is n=4 spaces.
-fpsc=n, --fixed-position-side-comment=n
This parameter tells perltidy to line up side comments in column number n whenever possible. The
default, n=0, will not do this.
-iscl, --ignore-side-comment-lengths
This parameter causes perltidy to ignore the length of side comments when setting line breaks. The
default, -niscl, is to include the length of side comments when breaking lines to stay within the
length prescribed by the -l=n maximum line length parameter. For example, the following long single
line would remain intact with -l=80 and -iscl:
perltidy -l=80 -iscl
$vmsfile =~ s/;[\d\-]*$//; # Clip off version number; we can use a newer version as well
whereas without the -iscl flag the line will be broken:
perltidy -l=80
$vmsfile =~ s/;[\d\-]*$//
; # Clip off version number; we can use a newer version as well
-hsc, --hanging-side-comments
By default, perltidy tries to identify and align "hanging side comments", which are something like
this:
my $IGNORE = 0; # This is a side comment
# This is a hanging side comment
# And so is this
A comment is considered to be a hanging side comment if (1) it immediately follows a line with a side
comment, or another hanging side comment, and (2) there is some leading whitespace on the line. To
deactivate this feature, use -nhsc or --nohanging-side-comments. If block comments are preceded by a
blank line, or have no leading whitespace, they will not be mistaken as hanging side comments.
Closing Side Comments
A closing side comment is a special comment which perltidy can automatically create and place after
the closing brace of a code block. They can be useful for code maintenance and debugging. The
command -csc (or --closing-side-comments) adds or updates closing side comments. For example, here
is a small code snippet
sub message {
if ( !defined( $_[0] ) ) {
print("Hello, World\n");
}
else {
print( $_[0], "\n" );
}
}
And here is the result of processing with "perltidy -csc":
sub message {
if ( !defined( $_[0] ) ) {
print("Hello, World\n");
}
else {
print( $_[0], "\n" );
}
} ## end sub message
A closing side comment was added for "sub message" in this case, but not for the "if" and "else"
blocks, because they were below the 6 line cutoff limit for adding closing side comments. This limit
may be changed with the -csci command, described below.
The command -dcsc (or --delete-closing-side-comments) reverses this process and removes these
comments.
Several commands are available to modify the behavior of these two basic commands, -csc and -dcsc:
-csci=n, or --closing-side-comment-interval=n
where "n" is the minimum number of lines that a block must have in order for a closing side
comment to be added. The default value is "n=6". To illustrate:
# perltidy -csci=2 -csc
sub message {
if ( !defined( $_[0] ) ) {
print("Hello, World\n");
} ## end if ( !defined( $_[0] ))
else {
print( $_[0], "\n" );
} ## end else [ if ( !defined( $_[0] ))
} ## end sub message
Now the "if" and "else" blocks are commented. However, now this has become very cluttered.
-cscp=string, or --closing-side-comment-prefix=string
where string is the prefix used before the name of the block type. The default prefix, shown
above, is "## end". This string will be added to closing side comments, and it will also be used
to recognize them in order to update, delete, and format them. Any comment identified as a
closing side comment will be placed just a single space to the right of its closing brace.
-cscl=string, or --closing-side-comment-list
where "string" is a list of block types to be tagged with closing side comments. By default, all
code block types preceded by a keyword or label (such as "if", "sub", and so on) will be tagged.
The -cscl command changes the default list to be any selected block types; see "Specifying Block
Types". For example, the following command requests that only "sub"'s, labels, "BEGIN", and
"END" blocks be affected by any -csc or -dcsc operation:
-cscl="sub : BEGIN END"
-csct=n, or --closing-side-comment-maximum-text=n
The text appended to certain block types, such as an "if" block, is whatever lies between the
keyword introducing the block, such as "if", and the opening brace. Since this might be too much
text for a side comment, there needs to be a limit, and that is the purpose of this parameter.
The default value is "n=20", meaning that no additional tokens will be appended to this text
after its length reaches 20 characters. Omitted text is indicated with "...". (Tokens,
including sub names, are never truncated, however, so actual lengths may exceed this). To
illustrate, in the above example, the appended text of the first block is " ( !defined( $_[0]
)...". The existing limit of "n=20" caused this text to be truncated, as indicated by the "...".
See the next flag for additional control of the abbreviated text.
-cscb, or --closing-side-comments-balanced
As discussed in the previous item, when the closing-side-comment-maximum-text limit is exceeded
the comment text must be truncated. Older versions of perltidy terminated with three dots, and
this can still be achieved with -ncscb:
perltidy -csc -ncscb
} ## end foreach my $foo (sort { $b cmp $a ...
However this causes a problem with editors which cannot recognize comments or are not configured
to do so because they cannot "bounce" around in the text correctly. The -cscb flag has been
added to help them by appending appropriate balancing structure:
perltidy -csc -cscb
} ## end foreach my $foo (sort { $b cmp $a ... })
The default is -cscb.
-csce=n, or --closing-side-comment-else-flag=n
The default, n=0, places the text of the opening "if" statement after any terminal "else".
If n=2 is used, then each "elsif" is also given the text of the opening "if" statement. Also, an
"else" will include the text of a preceding "elsif" statement. Note that this may result some
long closing side comments.
If n=1 is used, the results will be the same as n=2 whenever the resulting line length is less
than the maximum allowed.
-cscb, or --closing-side-comments-balanced
When using closing-side-comments, and the closing-side-comment-maximum-text limit is exceeded,
then the comment text must be abbreviated. It is terminated with three dots if the -cscb flag is
negated:
perltidy -csc -ncscb
} ## end foreach my $foo (sort { $b cmp $a ...
This causes a problem with older editors which do not recognize comments because they cannot
"bounce" around in the text correctly. The -cscb flag tries to help them by appending
appropriate terminal balancing structures:
perltidy -csc -cscb
} ## end foreach my $foo (sort { $b cmp $a ... })
The default is -cscb.
-cscw, or --closing-side-comment-warnings
This parameter is intended to help make the initial transition to the use of closing side
comments. It causes two things to happen if a closing side comment replaces an existing,
different closing side comment: first, an error message will be issued, and second, the original
side comment will be placed alone on a new specially marked comment line for later attention.
The intent is to avoid clobbering existing hand-written side comments which happen to match the
pattern of closing side comments. This flag should only be needed on the first run with -csc.
Important Notes on Closing Side Comments:
• Closing side comments are only placed on lines terminated with a closing brace. Certain closing
styles, such as the use of cuddled elses (-ce), preclude the generation of some closing side
comments.
• Please note that adding or deleting of closing side comments takes place only through the
commands -csc or -dcsc. The other commands, if used, merely modify the behavior of these two
commands.
• It is recommended that the -cscw flag be used along with -csc on the first use of perltidy on a
given file. This will prevent loss of any existing side comment data which happens to have the
csc prefix.
• Once you use -csc, you should continue to use it so that any closing side comments remain correct
as code changes. Otherwise, these comments will become incorrect as the code is updated.
• If you edit the closing side comments generated by perltidy, you must also change the prefix to
be different from the closing side comment prefix. Otherwise, your edits will be lost when you
rerun perltidy with -csc. For example, you could simply change "## end" to be "## End", since
the test is case sensitive. You may also want to use the -ssc flag to keep these modified
closing side comments spaced the same as actual closing side comments.
• Temporarily generating closing side comments is a useful technique for exploring and/or debugging
a perl script, especially one written by someone else. You can always remove them with -dcsc.
Static Block Comments
Static block comments are block comments with a special leading pattern, "##" by default, which will
be treated slightly differently from other block comments. They effectively behave as if they had
glue along their left and top edges, because they stick to the left edge and previous line when there
is no blank spaces in those places. This option is particularly useful for controlling how commented
code is displayed.
-sbc, --static-block-comments
When -sbc is used, a block comment with a special leading pattern, "##" by default, will be
treated specially.
Comments so identified are treated as follows:
• If there is no leading space on the line, then the comment will not be indented, and
otherwise it may be,
• no new blank line will be inserted before such a comment, and
• such a comment will never become a hanging side comment.
For example, assuming @month_of_year is left-adjusted:
@month_of_year = ( # -sbc (default)
'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct',
## 'Dec', 'Nov'
'Nov', 'Dec');
Without this convention, the above code would become
@month_of_year = ( # -nsbc
'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct',
## 'Dec', 'Nov'
'Nov', 'Dec'
);
which is not as clear. The default is to use -sbc. This may be deactivated with -nsbc.
-sbcp=string, --static-block-comment-prefix=string
This parameter defines the prefix used to identify static block comments when the -sbc parameter
is set. The default prefix is "##", corresponding to "-sbcp=##". The prefix is actually part of
a perl pattern used to match lines and it must either begin with "#" or "^#". In the first case
a prefix ^\s* will be added to match any leading whitespace, while in the second case the pattern
will match only comments with no leading whitespace. For example, to identify all comments as
static block comments, one would use "-sbcp=#". To identify all left-adjusted comments as static
block comments, use "-sbcp='^#'".
Please note that -sbcp merely defines the pattern used to identify static block comments; it will
not be used unless the switch -sbc is set. Also, please be aware that since this string is used
in a perl regular expression which identifies these comments, it must enable a valid regular
expression to be formed.
A pattern which can be useful is:
-sbcp=^#{2,}[^\s#]
This pattern requires a static block comment to have at least one character which is neither a #
nor a space. It allows a line containing only '#' characters to be rejected as a static block
comment. Such lines are often used at the start and end of header information in subroutines and
should not be separated from the intervening comments, which typically begin with just a single
'#'.
-osbc, --outdent-static-block-comments
The command -osbc will cause static block comments to be outdented by 2 spaces (or whatever -ci=n
has been set to), if possible.
Static Side Comments
Static side comments are side comments with a special leading pattern. This option can be useful for
controlling how commented code is displayed when it is a side comment.
-ssc, --static-side-comments
When -ssc is used, a side comment with a static leading pattern, which is "##" by default, will
be spaced only a single space from previous character, and it will not be vertically aligned with
other side comments.
The default is -nssc.
-sscp=string, --static-side-comment-prefix=string
This parameter defines the prefix used to identify static side comments when the -ssc parameter
is set. The default prefix is "##", corresponding to "-sscp=##".
Please note that -sscp merely defines the pattern used to identify static side comments; it will
not be used unless the switch -ssc is set. Also, note that this string is used in a perl regular
expression which identifies these comments, so it must enable a valid regular expression to be
formed.
Skipping Selected Sections of Code
Selected lines of code may be passed verbatim to the output without any formatting by marking the
starting and ending lines with special comments. There are two options for doing this. The first option
is called --format-skipping or -fs, and the second option is called --code-skipping or -cs.
In both cases the lines of code will be output without any changes. The difference is that in
--format-skipping perltidy will still parse the marked lines of code and check for errors, whereas in
--code-skipping perltidy will simply pass the lines to the output without any checking.
Both of these features are enabled by default and are invoked with special comment markers.
--format-skipping uses starting and ending markers '#<<<' and '#>>>', like this:
#<<< format skipping: do not let perltidy change my nice formatting
my @list = (1,
1, 1,
1, 2, 1,
1, 3, 3, 1,
1, 4, 6, 4, 1,);
#>>>
--code-skipping uses starting and ending markers '#<<V' and '#>>V', like this:
#<<V code skipping: perltidy will pass this verbatim without error checking
token ident_digit {
[ [ <?word> | _ | <?digit> ] <?ident_digit>
| <''>
]
};
#>>V
Additional text may appear on the special comment lines provided that it is separated from the marker by
at least one space, as in the above examples.
It is recommended to use --code-skipping only if you need to hide a block of an extended syntax which
would produce errors if parsed by perltidy, and use --format-skipping otherwise. This is because the
--format-skipping option provides the benefits of error checking, and there are essentially no
limitations on which lines to which it can be applied. The --code-skipping option, on the other hand,
does not do error checking and its use is more restrictive because the code which remains, after skipping
the marked lines, must be syntactically correct code with balanced containers.
These features should be used sparingly to avoid littering code with markers, but they can be helpful for
working around occasional problems.
Note that it may be possible to avoid the use of --format-skipping for the specific case of a comma-
separated list of values, as in the above example, by simply inserting a blank or comment somewhere
between the opening and closing parens. See the section "Controlling List Formatting".
The following sections describe the available controls for these options. They should not normally be
needed.
-fs, --format-skipping
As explained above, this flag, which is enabled by default, causes any code between special beginning
and ending comment markers to be passed to the output without formatting. The code between the
comments is still checked for errors however. The default beginning marker is #<<< and the default
ending marker is #>>>.
Format skipping begins when a format skipping beginning comment is seen and continues until a format-
skipping ending comment is found.
This feature can be disabled with -nfs. This should not normally be necessary.
-fsb=string, --format-skipping-begin=string
This and the next parameter allow the special beginning and ending comments to be changed. However,
it is recommended that they only be changed if there is a conflict between the default values and
some other use. If they are used, it is recommended that they only be entered in a .perltidyrc file,
rather than on a command line. This is because properly escaping these parameters on a command line
can be difficult.
If changed comment markers do not appear to be working, use the -log flag and examine the .LOG file
to see if and where they are being detected.
The -fsb=string parameter may be used to change the beginning marker for format skipping. The
default is equivalent to -fsb='#<<<'. The string that you enter must begin with a # and should be in
quotes as necessary to get past the command shell of your system. It is actually the leading text of
a pattern that is constructed by appending a '\s', so you must also include backslashes for
characters to be taken literally rather than as patterns.
Some examples show how example strings become patterns:
-fsb='#\{\{\{' becomes /^#\{\{\{\s/ which matches #{{{ but not #{{{{
-fsb='#\*\*' becomes /^#\*\*\s/ which matches #** but not #***
-fsb='#\*{2,}' becomes /^#\*{2,}\s/ which matches #** and #*****
-fse=string, --format-skipping-end=string
The -fse=string is the corresponding parameter used to change the ending marker for format skipping.
The default is equivalent to -fse='#<<<'.
The beginning and ending strings may be the same, but it is preferable to make them different for
clarity.
-cs, --code-skipping
As explained above, this flag, which is enabled by default, causes any code between special beginning
and ending comment markers to be directly passed to the output without any error checking or
formatting. Essentially, perltidy treats it as if it were a block of arbitrary text. The default
beginning marker is #<<V and the default ending marker is #>>V.
This feature can be disabled with -ncs. This should not normally be necessary.
-csb=string, --code-skipping-begin=string
This may be used to change the beginning comment for a --code-skipping section, and its use is
similar to the -fsb=string. The default is equivalent to -csb='#<<V'.
-cse=string, --code-skipping-end=string
This may be used to change the ending comment for a --code-skipping section, and its use is similar
to the -fse=string. The default is equivalent to -cse='#>>V'.
Line Break Control
The parameters in this section control breaks after non-blank lines of code. Blank lines are controlled
separately by parameters in the section "Blank Line Control".
-fnl, --freeze-newlines
If you do not want any changes to the line breaks within lines of code in your script, set -fnl, and
they will remain fixed, and the rest of the commands in this section and sections "Controlling List
Formatting", "Retaining or Ignoring Existing Line Breaks". You may want to use -noll with this.
Note: If you also want to keep your blank lines exactly as they are, you can use the -fbl flag which
is described in the section "Blank Line Control".
-ce, --cuddled-else
Enable the "cuddled else" style, in which "else" and "elsif" are follow immediately after the curly
brace closing the previous block. The default is not to use cuddled elses, and is indicated with the
flag -nce or --nocuddled-else. Here is a comparison of the alternatives:
# -ce
if ($task) {
yyy();
} else {
zzz();
}
# -nce (default)
if ($task) {
yyy();
}
else {
zzz();
}
In this example the keyword else is placed on the same line which begins with the preceding closing
block brace and is followed by its own opening block brace on the same line. Other keywords and
function names which are formatted with this "cuddled" style are elsif, continue, catch, finally.
Other block types can be formatted by specifying their names on a separate parameter -cbl, described
in a later section.
Cuddling between a pair of code blocks requires that the closing brace of the first block start a new
line. If this block is entirely on one line in the input file, it is necessary to decide if it
should be broken to allow cuddling. This decision is controlled by the flag -cbo=n discussed below.
The default and recommended value of -cbo=1 bases this decision on the first block in the chain. If
it spans multiple lines then cuddling is made and continues along the chain, regardless of the sizes
of subsequent blocks. Otherwise, short lines remain intact.
So for example, the -ce flag would not have any effect if the above snippet is rewritten as
if ($task) { yyy() }
else { zzz() }
If the first block spans multiple lines, then cuddling can be done and will continue for the
subsequent blocks in the chain, as illustrated in the previous snippet.
If there are blank lines between cuddled blocks they will be eliminated. If there are comments after
the closing brace where cuddling would occur then cuddling will be prevented. If this occurs,
cuddling will restart later in the chain if possible.
-cb, --cuddled-blocks
This flag is equivalent to -ce.
-cbl, --cuddled-block-list
The built-in default cuddled block types are else, elsif, continue, catch, finally.
Additional block types to which the -cuddled-blocks style applies can be defined by this parameter.
This parameter is a character string, giving a list of block types separated by commas or spaces.
For example, to cuddle code blocks of type sort, map and grep, in addition to the default types, the
string could be set to
-cbl="sort map grep"
or equivalently
-cbl=sort,map,grep
Note however that these particular block types are typically short so there might not be much
opportunity for the cuddled format style.
Using commas avoids the need to protect spaces with quotes.
As a diagnostic check, the flag --dump-cuddled-block-list or -dcbl can be used to view the hash of
values that are generated by this flag.
Finally, note that the -cbl flag by itself merely specifies which blocks are formatted with the
cuddled format. It has no effect unless this formatting style is activated with -ce.
-cblx, --cuddled-block-list-exclusive
When cuddled else formatting is selected with -ce, setting this flag causes perltidy to ignore its
built-in defaults and rely exclusively on the block types specified on the -cbl flag described in the
previous section. For example, to avoid using cuddled catch and finally, which among in the
defaults, the following set of parameters could be used:
perltidy -ce -cbl='else elsif continue' -cblx
-cbo=n, --cuddled-break-option=n
Cuddled formatting is only possible between a pair of code blocks if the closing brace of the first
block starts a new line. If a block is encountered which is entirely on a single line, and cuddled
formatting is selected, it is necessary to make a decision as to whether or not to "break" the block,
meaning to cause it to span multiple lines. This parameter controls that decision. The options are:
cbo=0 Never force a short block to break.
cbo=1 If the first of a pair of blocks is broken in the input file,
then break the second [DEFAULT].
cbo=2 Break open all blocks for maximal cuddled formatting.
The default and recommended value is cbo=1. With this value, if the starting block of a chain spans
multiple lines, then a cascade of breaks will occur for remaining blocks causing the entire chain to
be cuddled.
The option cbo=0 can produce erratic cuddling if there are numerous one-line blocks.
The option cbo=2 produces maximal cuddling but will not allow any short blocks.
-bl, --opening-brace-on-new-line
Use the flag -bl to place the opening brace on a new line:
if ( $input_file eq '-' ) # -bl
{
important_function();
}
This flag applies to all structural blocks, including named sub's (unless the -sbl flag is set -- see
next item).
The default style, -nbl, places an opening brace on the same line as the keyword introducing it. For
example,
if ( $input_file eq '-' ) { # -nbl (default)
-sbl, --opening-sub-brace-on-new-line
The flag -sbl can be used to override the value of -bl for the opening braces of named sub's. For
example,
perltidy -sbl
produces this result:
sub message
{
if (!defined($_[0])) {
print("Hello, World\n");
}
else {
print($_[0], "\n");
}
}
This flag is negated with -nsbl. If -sbl is not specified, the value of -bl is used.
-asbl, --opening-anonymous-sub-brace-on-new-line
The flag -asbl is like the -sbl flag except that it applies to anonymous sub's instead of named subs.
For example
perltidy -asbl
produces this result:
$a = sub
{
if ( !defined( $_[0] ) ) {
print("Hello, World\n");
}
else {
print( $_[0], "\n" );
}
};
This flag is negated with -nasbl, and the default is -nasbl.
-bli, --brace-left-and-indent
The flag -bli is the same as -bl but in addition it causes one unit of continuation indentation ( see
-ci ) to be placed before an opening and closing block braces.
For example,
if ( $input_file eq '-' ) # -bli
{
important_function();
}
By default, this extra indentation occurs for blocks of type: if, elsif, else, unless, for, foreach,
sub, while, until, and also with a preceding label. The next item shows how to change this.
-blil=s, --brace-left-and-indent-list=s
Use this parameter to change the types of block braces for which the -bli flag applies; see
"Specifying Block Types". For example, -blil='if elsif else' would apply it to only "if/elsif/else"
blocks.
-bar, --opening-brace-always-on-right
The default style, -nbl places the opening code block brace on a new line if it does not fit on the
same line as the opening keyword, like this:
if ( $bigwasteofspace1 && $bigwasteofspace2
|| $bigwasteofspace3 && $bigwasteofspace4 )
{
big_waste_of_time();
}
To force the opening brace to always be on the right, use the -bar flag. In this case, the above
example becomes
if ( $bigwasteofspace1 && $bigwasteofspace2
|| $bigwasteofspace3 && $bigwasteofspace4 ) {
big_waste_of_time();
}
A conflict occurs if both -bl and -bar are specified.
-otr, --opening-token-right and related flags
The -otr flag is a hint that perltidy should not place a break between a comma and an opening token.
For example:
# default formatting
push @{ $self->{$module}{$key} },
{
accno => $ref->{accno},
description => $ref->{description}
};
# perltidy -otr
push @{ $self->{$module}{$key} }, {
accno => $ref->{accno},
description => $ref->{description}
};
The flag -otr is actually an abbreviation for three other flags which can be used to control parens,
hash braces, and square brackets separately if desired:
-opr or --opening-paren-right
-ohbr or --opening-hash-brace-right
-osbr or --opening-square-bracket-right
-bbhb=n, --break-before-hash-brace=n and related flags
When a list of items spans multiple lines, the default formatting is to place the opening brace (or
other container token) at the end of the starting line, like this:
$romanNumerals = {
one => 'I',
two => 'II',
three => 'III',
four => 'IV',
};
This flag can change the default behavior to cause a line break to be placed before the opening brace
according to the value given to the integer n:
-bbhb=0 never break [default]
-bbhb=1 stable: break if the input script had a break
-bbhb=2 break if list is 'complex' (see note below)
-bbhb=3 always break
For example,
# perltidy -bbhb=3
$romanNumerals =
{
one => 'I',
two => 'II',
three => 'III',
four => 'IV',
};
There are several points to note about this flag:
• This parameter only applies if the opening brace is preceded by an '=' or '=>'.
• This parameter only applies if the contents of the container looks like a list. The contents
need to contain some commas or '=>'s at the next interior level to be considered a list.
• For the n=2 option, a list is considered 'complex' if it is part of a nested list structure which
spans multiple lines in the input file.
• If multiple opening tokens have been 'welded' together with the -wn parameter, then this
parameter has no effect.
• The indentation of the braces will normally be one level of continuation indentation by default.
This can be changed with the parameter -bbhbi=n in the next section.
• Similar flags for controlling parens and square brackets are given in the subsequent section.
-bbhbi=n, --break-before-hash-brace-and-indent=n
This flag is a companion to -bbhb=n for controlling the indentation of an opening hash brace which is
placed on a new line by that parameter. The indentation is as follows:
-bbhbi=0 one continuation level [default]
-bbhbi=1 outdent by one continuation level
-bbhbi=2 indent one full indentation level
For example:
# perltidy -bbhb=3 -bbhbi=1
$romanNumerals =
{
one => 'I',
two => 'II',
three => 'III',
four => 'IV',
};
# perltidy -bbhb=3 -bbhbi=2
$romanNumerals =
{
one => 'I',
two => 'II',
three => 'III',
four => 'IV',
};
Note that this parameter has no effect unless -bbhb=n is also set.
-bbsb=n, --break-before-square-bracket=n
This flag is similar to the flag described above, except it applies to lists contained within square
brackets.
-bbsb=0 never break [default]
-bbsb=1 stable: break if the input script had a break
-bbsb=2 break if list is 'complex' (part of nested list structure)
-bbsb=3 always break
-bbsbi=n, --break-before-square-bracket-and-indent=n
This flag is a companion to -bbsb=n for controlling the indentation of an opening square bracket
which is placed on a new line by that parameter. The indentation is as follows:
-bbsbi=0 one continuation level [default]
-bbsbi=1 outdent by one continuation level
-bbsbi=2 indent one full indentation level
-bbp=n, --break-before-paren=n
This flag is similar to -bbhb=n, described above, except it applies to lists contained within parens.
-bbp=0 never break [default]
-bbp=1 stable: break if the input script had a break
-bpb=2 break if list is 'complex' (part of nested list structure)
-bbp=3 always break
-bbpi=n, --break-before-paren-and-indent=n
This flag is a companion to -bbp=n for controlling the indentation of an opening paren which is
placed on a new line by that parameter. The indentation is as follows:
-bbpi=0 one continuation level [default]
-bbpi=1 outdent by one continuation level
-bbpi=2 indent one full indentation level
-wn, --weld-nested-containers
The -wn flag causes closely nested pairs of opening and closing container symbols (curly braces,
brackets, or parens) to be "welded" together, meaning that they are treated as if combined into a
single unit, with the indentation of the innermost code reduced to be as if there were just a single
container symbol.
For example:
# default formatting
do {
{
next if $x == $y;
}
} until $x++ > $z;
# perltidy -wn
do { {
next if $x == $y;
} } until $x++ > $z;
When this flag is set perltidy makes a preliminary pass through the file and identifies all nested
pairs of containers. To qualify as a nested pair, the closing container symbols must be immediately
adjacent and the opening symbols must either (1) be adjacent as in the above example, or (2) have an
anonymous sub declaration following an outer opening container symbol which is not a code block
brace, or (3) have an outer opening paren separated from the inner opening symbol by any single non-
container symbol or something that looks like a function evaluation, as illustrated in the next
examples.
Any container symbol may serve as both the inner container of one pair and as the outer container of
an adjacent pair. Consequently, any number of adjacent opening or closing symbols may join together
in weld. For example, here are three levels of wrapped function calls:
# default formatting
my (@date_time) = Localtime(
Date_to_Time(
Add_Delta_DHMS(
$year, $month, $day, $hour, $minute, $second,
'0', $offset, '0', '0'
)
)
);
# perltidy -wn
my (@date_time) = Localtime( Date_to_Time( Add_Delta_DHMS(
$year, $month, $day, $hour, $minute, $second,
'0', $offset, '0', '0'
) ) );
Notice how the indentation of the inner lines are reduced by two levels in this case. This example
also shows the typical result of this formatting, namely it is a sandwich consisting of an initial
opening layer, a central section of any complexity forming the "meat" of the sandwich, and a final
closing layer. This predictable structure helps keep the compacted structure readable.
The inner sandwich layer is required to be at least one line thick. If this cannot be achieved,
welding does not occur. This constraint can cause formatting to take a couple of iterations to
stabilize when it is first applied to a script. The -conv flag can be used to insure that the final
format is achieved in a single run.
Here is an example illustrating a welded container within a welded containers:
# default formatting
$x->badd(
bmul(
$class->new(
abs(
$sx * int( $xr->numify() ) & $sy * int( $yr->numify() )
)
),
$m
)
);
# perltidy -wn
$x->badd( bmul(
$class->new( abs(
$sx * int( $xr->numify() ) & $sy * int( $yr->numify() )
) ),
$m
) );
The welded closing tokens are by default on a separate line but this can be modified with the -vtc=n
flag (described in the next section). For example, the same example adding -vtc=2 is
# perltidy -wn -vtc=2
$x->badd( bmul(
$class->new( abs(
$sx * int( $xr->numify() ) & $sy * int( $yr->numify() ) ) ),
$m ) );
This format option is quite general but there are some limitations.
One limitation is that any line length limit still applies and can cause long welded sections to be
broken into multiple lines.
Another limitation is that an opening symbol which delimits quoted text cannot be included in a
welded pair. This is because quote delimiters are treated specially in perltidy.
Finally, the stacking of containers defined by this flag have priority over any other container
stacking flags. This is because any welding is done first.
-wnxl=s, --weld-nested-exclusion-list
The -wnxl=s flag provides some control over the types of containers which can be welded. The -wn
flag by default is "greedy" in welding adjacent containers. If it welds more types of containers
than desired, this flag provides a capability to reduce the amount of welding by specifying a list of
things which should not be welded.
The logic in perltidy to apply this is straightforward. As each container token is being considered
for joining a weld, any exclusion rules are consulted and used to reject the weld if necessary.
This list is a string with space-separated items. Each item consists of up to three pieces of
information: (1) an optional position, (2) an optional preceding type, and (3) a container type.
The only required piece of information is a container type, which is one of '(', '[', '{' or 'q'.
The first three of these are container tokens and the last represents a quoted list. For example the
string
-wnxl='[ { q'
means do NOT include square-bracets, braces, or quotes in any welds. The only unspecified container
is '(', so this string means that only welds involving parens will be made.
To illustrate, following welded snippet consists of a chain of three welded containers with types '('
'[' and 'q':
# perltidy -wn
skip_symbols( [ qw(
Perl_dump_fds
Perl_ErrorNo
Perl_GetVars
PL_sys_intern
) ] );
Even though the qw term uses parens as the quote delimiter, it has a special type 'q' here. If it
appears in a weld it always appears at the end of the welded chain.
Any of the container types '[', '{', and '(' may be prefixed with a position indicator which is
either '^', to indicate the first token of a welded sequence, or '.', to indicate an interior token
of a welded sequence. (Since a quoted string 'q' always ends a chain it does need a position
indicator).
For example, if we do not want a sequence of welded containers to start with a square bracket we
could use
-wnxl='^['
In the above snippet, there is a square bracket but it does not start the chain, so the formatting
would be unchanged if it were formatted with this restriction.
A third optional item of information which can be given is an alphanumeric letter which is used to
limit the selection further depending on the type of token immediately before the container. If
given, it goes just before the container symbol. The possible letters are currently 'k', 'K', 'f',
'F', 'w', and 'W', with these meanings:
'k' matches if the previous nonblank token is a perl builtin keyword (such as 'if', 'while'),
'K' matches if 'k' does not, meaning that the previous token is not a keyword.
'f' matches if the previous token is a function other than a keyword.
'F' matches if 'f' does not.
'w' matches if either 'k' or 'f' match.
'W' matches if 'w' does not.
For example, compare
# perltidy -wn
if ( defined( $_Cgi_Query{
$Config{'methods'}{'authentication'}{'remote'}{'cgi'}{'username'}
} ) )
with
# perltidy -wn -wnxl='^K( {'
if ( defined(
$_Cgi_Query{ $Config{'methods'}{'authentication'}{'remote'}{'cgi'}
{'username'} }
) )
The first case does maximum welding. In the second case the leading paren is retained by the rule (it
would have been rejected if preceded by a non-keyword) but the curly brace is rejected by the rule.
Here are some additional example strings and their meanings:
'^(' - the weld must not start with a paren
'.(' - the second and later tokens may not be parens
'.w(' - the second and later tokens may not keyword or function call parens
'(' - no parens in a weld
'^K(' - exclude a leading paren preceded by a non-keyword
'.k(' - exclude a secondary paren preceded by a keyword
'[ {' - exclude all brackets and braces
'[ ( ^K{' - exclude everything except nested structures like do {{ ... }}
Vertical tightness of non-block curly braces, parentheses, and square brackets.
These parameters control what shall be called vertical tightness. Here are the main points:
• Opening tokens (except for block braces) are controlled by -vt=n, or --vertical-tightness=n,
where
-vt=0 always break a line after opening token (default).
-vt=1 do not break unless this would produce more than one
step in indentation in a line.
-vt=2 never break a line after opening token
• You must also use the -lp flag when you use the -vt flag; the reason is explained below.
• Closing tokens (except for block braces) are controlled by -vtc=n, or
--vertical-tightness-closing=n, where
-vtc=0 always break a line before a closing token (default),
-vtc=1 do not break before a closing token which is followed
by a semicolon or another closing token, and is not in
a list environment.
-vtc=2 never break before a closing token.
-vtc=3 Like -vtc=1 except always break before a closing token
if the corresponding opening token follows an = or =>.
The rules for -vtc=1 and -vtc=3 are designed to maintain a reasonable balance between tightness
and readability in complex lists.
• Different controls may be applied to different token types, and it is also possible to control
block braces; see below.
• Finally, please note that these vertical tightness flags are merely hints to the formatter, and
it cannot always follow them. Things which make it difficult or impossible include comments,
blank lines, blocks of code within a list, and possibly the lack of the -lp parameter. Also,
these flags may be ignored for very small lists (2 or 3 lines in length).
Here are some examples:
# perltidy -lp -vt=0 -vtc=0
%romanNumerals = (
one => 'I',
two => 'II',
three => 'III',
four => 'IV',
);
# perltidy -lp -vt=1 -vtc=0
%romanNumerals = ( one => 'I',
two => 'II',
three => 'III',
four => 'IV',
);
# perltidy -lp -vt=1 -vtc=1
%romanNumerals = ( one => 'I',
two => 'II',
three => 'III',
four => 'IV', );
# perltidy -vtc=3
my_function(
one => 'I',
two => 'II',
three => 'III',
four => 'IV', );
# perltidy -vtc=3
%romanNumerals = (
one => 'I',
two => 'II',
three => 'III',
four => 'IV',
);
In the last example for -vtc=3, the opening paren is preceded by an equals so the closing paren is
placed on a new line.
The difference between -vt=1 and -vt=2 is shown here:
# perltidy -lp -vt=1
$init->add(
mysprintf( "(void)find_threadsv(%s);",
cstring( $threadsv_names[ $op->targ ] )
)
);
# perltidy -lp -vt=2
$init->add( mysprintf( "(void)find_threadsv(%s);",
cstring( $threadsv_names[ $op->targ ] )
)
);
With -vt=1, the line ending in "add(" does not combine with the next line because the next line is
not balanced. This can help with readability, but -vt=2 can be used to ignore this rule.
The tightest, and least readable, code is produced with both "-vt=2" and "-vtc=2":
# perltidy -lp -vt=2 -vtc=2
$init->add( mysprintf( "(void)find_threadsv(%s);",
cstring( $threadsv_names[ $op->targ ] ) ) );
Notice how the code in all of these examples collapses vertically as -vt increases, but the
indentation remains unchanged. This is because perltidy implements the -vt parameter by first
formatting as if -vt=0, and then simply overwriting one output line on top of the next, if possible,
to achieve the desired vertical tightness. The -lp indentation style has been designed to allow this
vertical collapse to occur, which is why it is required for the -vt parameter.
The -vt=n and -vtc=n parameters apply to each type of container token. If desired, vertical
tightness controls can be applied independently to each of the closing container token types.
The parameters for controlling parentheses are -pvt=n or --paren-vertical-tightness=n, and -pvtc=n or
--paren-vertical-tightness-closing=n.
Likewise, the parameters for square brackets are -sbvt=n or --square-bracket-vertical-tightness=n,
and -sbvtc=n or --square-bracket-vertical-tightness-closing=n.
Finally, the parameters for controlling non-code block braces are -bvt=n or
--brace-vertical-tightness=n, and -bvtc=n or --brace-vertical-tightness-closing=n.
In fact, the parameter -vt=n is actually just an abbreviation for -pvt=n -bvt=n sbvt=n, and likewise
-vtc=n is an abbreviation for -pvtc=n -bvtc=n -sbvtc=n.
-bbvt=n or --block-brace-vertical-tightness=n
The -bbvt=n flag is just like the -vt=n flag but applies to opening code block braces.
-bbvt=0 break after opening block brace (default).
-bbvt=1 do not break unless this would produce more than one
step in indentation in a line.
-bbvt=2 do not break after opening block brace.
It is necessary to also use either -bl or -bli for this to work, because, as with other vertical
tightness controls, it is implemented by simply overwriting a line ending with an opening block brace
with the subsequent line. For example:
# perltidy -bli -bbvt=0
if ( open( FILE, "< $File" ) )
{
while ( $File = <FILE> )
{
$In .= $File;
$count++;
}
close(FILE);
}
# perltidy -bli -bbvt=1
if ( open( FILE, "< $File" ) )
{ while ( $File = <FILE> )
{ $In .= $File;
$count++;
}
close(FILE);
}
By default this applies to blocks associated with keywords if, elsif, else, unless, for, foreach,
sub, while, until, and also with a preceding label. This can be changed with the parameter
-bbvtl=string, or --block-brace-vertical-tightness-list=string, where string is a space-separated
list of block types. For more information on the possible values of this string, see "Specifying
Block Types"
For example, if we want to just apply this style to "if", "elsif", and "else" blocks, we could use
"perltidy -bli -bbvt=1 -bbvtl='if elsif else'".
There is no vertical tightness control for closing block braces; with one exception they will be
placed on separate lines. The exception is that a cascade of closing block braces may be stacked on
a single line. See -scbb.
-sot, --stack-opening-tokens and related flags
The -sot flag tells perltidy to "stack" opening tokens when possible to avoid lines with isolated
opening tokens.
For example:
# default
$opt_c = Text::CSV_XS->new(
{
binary => 1,
sep_char => $opt_c,
always_quote => 1,
}
);
# -sot
$opt_c = Text::CSV_XS->new( {
binary => 1,
sep_char => $opt_c,
always_quote => 1,
}
);
For detailed control of individual closing tokens the following controls can be used:
-sop or --stack-opening-paren
-sohb or --stack-opening-hash-brace
-sosb or --stack-opening-square-bracket
-sobb or --stack-opening-block-brace
The flag -sot is an abbreviation for -sop -sohb -sosb.
The flag -sobb is an abbreviation for -bbvt=2 -bbvtl='*'. This will case a cascade of opening block
braces to appear on a single line, although this an uncommon occurrence except in test scripts.
-sct, --stack-closing-tokens and related flags
The -sct flag tells perltidy to "stack" closing tokens when possible to avoid lines with isolated
closing tokens.
For example:
# default
$opt_c = Text::CSV_XS->new(
{
binary => 1,
sep_char => $opt_c,
always_quote => 1,
}
);
# -sct
$opt_c = Text::CSV_XS->new(
{
binary => 1,
sep_char => $opt_c,
always_quote => 1,
} );
The -sct flag is somewhat similar to the -vtc flags, and in some cases it can give a similar result.
The difference is that the -vtc flags try to avoid lines with leading opening tokens by "hiding" them
at the end of a previous line, whereas the -sct flag merely tries to reduce the number of lines with
isolated closing tokens by stacking them but does not try to hide them. For example:
# -vtc=2
$opt_c = Text::CSV_XS->new(
{
binary => 1,
sep_char => $opt_c,
always_quote => 1, } );
For detailed control of the stacking of individual closing tokens the following controls can be used:
-scp or --stack-closing-paren
-schb or --stack-closing-hash-brace
-scsb or --stack-closing-square-bracket
-scbb or --stack-closing-block-brace
The flag -sct is an abbreviation for stacking the non-block closing tokens, -scp -schb -scsb.
Stacking of closing block braces, -scbb, causes a cascade of isolated closing block braces to be
combined into a single line as in the following example:
# -scbb:
for $w1 (@w1) {
for $w2 (@w2) {
for $w3 (@w3) {
for $w4 (@w4) {
push( @lines, "$w1 $w2 $w3 $w4\n" );
} } } }
To simplify input even further for the case in which both opening and closing non-block containers
are stacked, the flag -sac or --stack-all-containers is an abbreviation for -sot -sct.
Please note that if both opening and closing tokens are to be stacked, then the newer flag
-weld-nested-containers may be preferable because it insures that stacking is always done
symmetrically. It also removes an extra level of unnecessary indentation within welded containers.
It is able to do this because it works on formatting globally rather than locally, as the -sot and
-sct flags do.
-dnl, --delete-old-newlines
By default, perltidy first deletes all old line break locations, and then it looks for good break
points to match the desired line length. Use -ndnl or --nodelete-old-newlines to force perltidy to
retain all old line break points.
-anl, --add-newlines
By default, perltidy will add line breaks when necessary to create continuations of long lines and to
improve the script appearance. Use -nanl or --noadd-newlines to prevent any new line breaks.
This flag does not prevent perltidy from eliminating existing line breaks; see --freeze-newlines to
completely prevent changes to line break points.
Controlling whether perltidy breaks before or after operators
Four command line parameters provide some control over whether a line break should be before or after
specific token types. Two parameters give detailed control:
-wba=s or --want-break-after=s, and
-wbb=s or --want-break-before=s.
These parameters are each followed by a quoted string, s, containing a list of token types (separated
only by spaces). No more than one of each of these parameters should be specified, because repeating
a command-line parameter always overwrites the previous one before perltidy ever sees it.
By default, perltidy breaks after these token types:
% + - * / x != == >= <= =~ !~ < > | &
= **= += *= &= <<= &&= -= /= |= >>= ||= //= .= %= ^= x=
And perltidy breaks before these token types by default:
. << >> -> && || //
To illustrate, to cause a break after a concatenation operator, '.', rather than before it, the
command line would be
-wba="."
As another example, the following command would cause a break before math operators '+', '-', '/',
and '*':
-wbb="+ - / *"
These commands should work well for most of the token types that perltidy uses (use
--dump-token-types for a list). Also try the -D flag on a short snippet of code and look at the
.DEBUG file to see the tokenization. However, for a few token types there may be conflicts with
hardwired logic which cause unexpected results. One example is curly braces, which should be
controlled with the parameter bl provided for that purpose.
WARNING Be sure to put these tokens in quotes to avoid having them misinterpreted by your command
shell.
Two additional parameters are available which, though they provide no further capability, can
simplify input are:
-baao or --break-after-all-operators,
-bbao or --break-before-all-operators.
The -baao sets the default to be to break after all of the following operators:
% + - * / x != == >= <= =~ !~ < > | &
= **= += *= &= <<= &&= -= /= |= >>= ||= //= .= %= ^= x=
. : ? && || and or err xor
and the -bbao flag sets the default to break before all of these operators. These can be used to
define an initial break preference which can be fine-tuned with the -wba and -wbb flags. For
example, to break before all operators except an = one could use --bbao -wba='=' rather than listing
every single perl operator except = on a -wbb flag.
Controlling List Formatting
Perltidy attempts to format lists of comma-separated values in tables which look good. Its default
algorithms usually work well, but sometimes they don't. In this case, there are several methods
available to control list formatting.
A very simple way to prevent perltidy from changing the line breaks within a comma-separated list of
values is to insert a blank line, comment, or side-comment anywhere between the opening and closing
parens (or braces or brackets). This causes perltidy to skip over its list formatting logic. (The
reason is that any of these items put a constraint on line breaks, and perltidy needs complete control
over line breaks within a container to adjust a list layout). For example, let us consider
my @list = (1,
1, 1,
1, 2, 1,
1, 3, 3, 1,
1, 4, 6, 4, 1,);
The default formatting, which allows a maximum line length of 80, will flatten this down to one line:
# perltidy (default)
my @list = ( 1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 6, 4, 1, );
This formatting loses important information. If we place a side comment on one of the lines, for
example, we get the following result with with default formatting parameters:
my @list = (
1, # a side comment, comment, or blank keeps list intact
1, 1,
1, 2, 1,
1, 3, 3, 1,
1, 4, 6, 4, 1,
);
We could achieve the same result with a blank line or full comment anywhere between the opening and
closing parens.
For another possibility see the -fs flag in "Skipping Selected Sections of Code".
-boc, --break-at-old-comma-breakpoints
The -boc flag is another way to prevent comma-separated lists from being reformatted. Using -boc on
the above example, plus additional flags to retain the original style, yields
# perltidy -boc -lp -pt=2 -vt=1 -vtc=1
my @list = (1,
1, 1,
1, 2, 1,
1, 3, 3, 1,
1, 4, 6, 4, 1,);
A disadvantage of this flag is that all tables in the file must already be nicely formatted.
-mft=n, --maximum-fields-per-table=n
If the computed number of fields for any table exceeds n, then it will be reduced to n. The default
value for n is a large number, 40. While this value should probably be left unchanged as a general
rule, it might be used on a small section of code to force a list to have a particular number of
fields per line, and then either the -boc flag could be used to retain this formatting, or a single
comment could be introduced somewhere to freeze the formatting in future applications of perltidy.
# perltidy -mft=2
@month_of_year = (
'Jan', 'Feb',
'Mar', 'Apr',
'May', 'Jun',
'Jul', 'Aug',
'Sep', 'Oct',
'Nov', 'Dec'
);
-cab=n, --comma-arrow-breakpoints=n
A comma which follows a comma arrow, '=>', is given special consideration. In a long list, it is
common to break at all such commas. This parameter can be used to control how perltidy breaks at
these commas. (However, it will have no effect if old comma breaks are being forced because -boc is
used). The possible values of n are:
n=0 break at all commas after =>
n=1 stable: break at all commas after => if container is open,
EXCEPT FOR one-line containers
n=2 break at all commas after =>, BUT try to form the maximum
one-line container lengths
n=3 do not treat commas after => specially at all
n=4 break everything: like n=0 but ALSO break a short container with
a => not followed by a comma when -vt=0 is used
n=5 stable: like n=1 but ALSO break at open one-line containers when
-vt=0 is used (default)
For example, given the following single line, perltidy by default will not add any line breaks
because it would break the existing one-line container:
bless { B => $B, Root => $Root } => $package;
Using -cab=0 will force a break after each comma-arrow item:
# perltidy -cab=0:
bless {
B => $B,
Root => $Root
} => $package;
If perltidy is subsequently run with this container broken, then by default it will break after each
'=>' because the container is now broken. To reform a one-line container, the parameter -cab=2 could
be used.
The flag -cab=3 can be used to prevent these commas from being treated specially. In this case, an
item such as "01" => 31 is treated as a single item in a table. The number of fields in this table
will be determined by the same rules that are used for any other table. Here is an example.
# perltidy -cab=3
my %last_day = (
"01" => 31, "02" => 29, "03" => 31, "04" => 30,
"05" => 31, "06" => 30, "07" => 31, "08" => 31,
"09" => 30, "10" => 31, "11" => 30, "12" => 31
);
Retaining or Ignoring Existing Line Breaks
Several additional parameters are available for controlling the extent to which line breaks in the input
script influence the output script. In most cases, the default parameter values are set so that, if a
choice is possible, the output style follows the input style. For example, if a short logical container
is broken in the input script, then the default behavior is for it to remain broken in the output script.
Most of the parameters in this section would only be required for a one-time conversion of a script from
short container lengths to longer container lengths. The opposite effect, of converting long container
lengths to shorter lengths, can be obtained by temporarily using a short maximum line length.
-bol, --break-at-old-logical-breakpoints
By default, if a logical expression is broken at a "&&", "||", "and", or "or", then the container
will remain broken. Also, breaks at internal keywords "if" and "unless" will normally be retained.
To prevent this, and thus form longer lines, use -nbol.
Please note that this flag does not duplicate old logical breakpoints. They are merely used as a
hint with this flag that a statement should remain broken. Without this flag, perltidy will normally
try to combine relatively short expressions into a single line.
For example, given this snippet:
return unless $cmd = $cmd || ($dot
&& $Last_Shell) || &prompt('|');
# perltidy -bol [default]
return
unless $cmd = $cmd
|| ( $dot
&& $Last_Shell )
|| &prompt('|');
# perltidy -nbol
return unless $cmd = $cmd || ( $dot && $Last_Shell ) || &prompt('|');
-bom, --break-at-old-method-breakpoints
By default, a method call arrow "->" is considered a candidate for a breakpoint, but method chains
will fill to the line width before a break is considered. With -bom, breaks before the arrow are
preserved, so if you have preformatted a method chain:
my $q = $rs
->related_resultset('CDs')
->related_resultset('Tracks')
->search({
'track.id' => {-ident => 'none_search.id'},
})->as_query;
It will keep these breaks, rather than become this:
my $q = $rs->related_resultset('CDs')->related_resultset('Tracks')->search({
'track.id' => {-ident => 'none_search.id'},
})->as_query;
This flag will also look for and keep a 'cuddled' style of calls, in which lines begin with a closing
paren followed by a call arrow, as in this example:
# perltidy -bom -wn
my $q = $rs->related_resultset(
'CDs'
)->related_resultset(
'Tracks'
)->search( {
'track.id' => { -ident => 'none_search.id' },
} )->as_query;
You may want to include the -weld-nested-containers flag in this case to keep nested braces and
parens together, as in the last line.
-bos, --break-at-old-semicolon-breakpoints
Semicolons are normally placed at the end of a statement. This means that formatted lines do not
normally begin with semicolons. If the input stream has some lines which begin with semicolons,
these can be retained by setting this flag. For example, consider the following two-line input
snippet:
$z = sqrt($x**2 + $y**2)
;
The default formatting will be:
$z = sqrt( $x**2 + $y**2 );
The result using perltidy -bos keeps the isolated semicolon:
$z = sqrt( $x**2 + $y**2 )
;
The default is not to do this, -nbos.
-bok, --break-at-old-keyword-breakpoints
By default, perltidy will retain a breakpoint before keywords which may return lists, such as "sort"
and <map>. This allows chains of these operators to be displayed one per line. Use -nbok to prevent
retaining these breakpoints.
-bot, --break-at-old-ternary-breakpoints
By default, if a conditional (ternary) operator is broken at a ":", then it will remain broken. To
prevent this, and thereby form longer lines, use -nbot.
-boa, --break-at-old-attribute-breakpoints
By default, if an attribute list is broken at a ":" in the source file, then it will remain broken.
For example, given the following code, the line breaks at the ':'s will be retained:
my @field
: field
: Default(1)
: Get('Name' => 'foo') : Set('Name');
If the attributes are on a single line in the source code then they will remain on a single line if
possible.
To prevent this, and thereby always form longer lines, use -nboa.
Keeping old breakpoints at specific token types
Two command line parameters provide detailed control over whether perltidy should keep an old line
break before or after a specific token type:
-kbb=s or --keep-old-breakpoints-before=s, and
-kba=s or --keep-old-breakpoints-after=s
These parameters are each followed by a quoted string, s, containing a list of token types (separated
only by spaces). No more than one of each of these parameters should be specified, because repeating
a command-line parameter always overwrites the previous one before perltidy ever sees it.
For example, -kbb='=>' means that if an input line begins with a '=>' then the output script should
also have a line break before that token.
For example, given the script:
method 'foo'
=> [ Int, Int ]
=> sub {
my ( $self, $x, $y ) = ( shift, @_ );
...;
};
# perltidy [default]
method 'foo' => [ Int, Int ] => sub {
my ( $self, $x, $y ) = ( shift, @_ );
...;
};
# perltidy -kbb='=>'
method 'foo'
=> [ Int, Int ]
=> sub {
my ( $self, $x, $y ) = ( shift, @_ );
...;
};
-iob, --ignore-old-breakpoints
Use this flag to tell perltidy to ignore existing line breaks to the maximum extent possible. This
will tend to produce the longest possible containers, regardless of type, which do not exceed the
line length limit. But please note that this parameter has priority over all other parameters
requesting that certain old breakpoints be kept.
-kis, --keep-interior-semicolons
Use the -kis flag to prevent breaking at a semicolon if there was no break there in the input file.
Normally perltidy places a newline after each semicolon which terminates a statement unless several
statements are contained within a one-line brace block. To illustrate, consider the following input
lines:
dbmclose(%verb_delim); undef %verb_delim;
dbmclose(%expanded); undef %expanded;
The default is to break after each statement, giving
dbmclose(%verb_delim);
undef %verb_delim;
dbmclose(%expanded);
undef %expanded;
With perltidy -kis the multiple statements are retained:
dbmclose(%verb_delim); undef %verb_delim;
dbmclose(%expanded); undef %expanded;
The statements are still subject to the specified value of maximum-line-length and will be broken if
this maximum is exceeded.
Blank Line Control
Blank lines can improve the readability of a script if they are carefully placed. Perltidy has several
commands for controlling the insertion, retention, and removal of blank lines.
-fbl, --freeze-blank-lines
Set -fbl if you want to the blank lines in your script to remain exactly as they are. The rest of
the parameters in this section may then be ignored. (Note: setting the -fbl flag is equivalent to
setting -mbl=0 and -kbl=2).
-bbc, --blanks-before-comments
A blank line will be introduced before a full-line comment. This is the default. Use -nbbc or
--noblanks-before-comments to prevent such blank lines from being introduced.
-blbs=n, --blank-lines-before-subs=n
The parameter -blbs=n requests that least n blank lines precede a sub definition which does not
follow a comment and which is more than one-line long. The default is <-blbs=1>. BEGIN and END
blocks are included.
The requested number of blanks statement will be inserted regardless of the value of
--maximum-consecutive-blank-lines=n (-mbl=n) with the exception that if -mbl=0 then no blanks will be
output.
This parameter interacts with the value k of the parameter --maximum-consecutive-blank-lines=k
(-mbl=k) as follows:
1. If -mbl=0 then no blanks will be output. This allows all blanks to be suppressed with a single
parameter. Otherwise,
2. If the number of old blank lines in the script is less than n then additional blanks will be
inserted to make the total n regardless of the value of -mbl=k.
3. If the number of old blank lines in the script equals or exceeds n then this parameter has no
effect, however the total will not exceed value specified on the -mbl=k flag.
-blbp=n, --blank-lines-before-packages=n
The parameter -blbp=n requests that least n blank lines precede a package which does not follow a
comment. The default is -blbp=1.
This parameter interacts with the value k of the parameter --maximum-consecutive-blank-lines=k
(-mbl=k) in the same way as described for the previous item -blbs=n.
-bbs, --blanks-before-subs
For compatibility with previous versions, -bbs or --blanks-before-subs is equivalent to -blbp=1 and
-blbs=1.
Likewise, -nbbs or --noblanks-before-subs is equivalent to -blbp=0 and -blbs=0.
-bbb, --blanks-before-blocks
A blank line will be introduced before blocks of coding delimited by for, foreach, while, until, and
if, unless, in the following circumstances:
• The block is not preceded by a comment.
• The block is not a one-line block.
• The number of consecutive non-blank lines at the current indentation depth is at least -lbl (see
next section).
This is the default. The intention of this option is to introduce some space within dense coding.
This is negated with -nbbb or --noblanks-before-blocks.
-lbl=n --long-block-line-count=n
This controls how often perltidy is allowed to add blank lines before certain block types (see
previous section). The default is 8. Entering a value of 0 is equivalent to entering a very large
number.
-blao=i or --blank-lines-after-opening-block=i
This control places a minimum of i blank lines after a line which ends with an opening block brace of
a specified type. By default, this only applies to the block of a named sub, but this can be changed
(see -blaol below). The default is not to do this (i=0).
Please see the note below on using the -blao and -blbc options.
-blbc=i or --blank-lines-before-closing-block=i
This control places a minimum of i blank lines before a line which begins with a closing block brace
of a specified type. By default, this only applies to the block of a named sub, but this can be
changed (see -blbcl below). The default is not to do this (i=0).
-blaol=s or --blank-lines-after-opening-block-list=s
The parameter s is a list of block type keywords to which the flag -blao should apply. The section
"Specifying Block Types" explains how to list block types.
-blbcl=s or --blank-lines-before-closing-block-list=s
This parameter is a list of block type keywords to which the flag -blbc should apply. The section
"Specifying Block Types" explains how to list block types.
Note on using the -blao and -blbc options.
These blank line controls introduce a certain minimum number of blank lines in the text, but the
final number of blank lines may be greater, depending on values of the other blank line controls and
the number of old blank lines. A consequence is that introducing blank lines with these and other
controls cannot be exactly undone, so some experimentation with these controls is recommended before
using them.
For example, suppose that for some reason we decide to introduce one blank space at the beginning and
ending of all blocks. We could do this using
perltidy -blao=2 -blbc=2 -blaol='*' -blbcl='*' filename
Now suppose the script continues to be developed, but at some later date we decide we don't want
these spaces after all. We might expect that running with the flags -blao=0 and -blbc=0 will undo
them. However, by default perltidy retains single blank lines, so the blank lines remain.
We can easily fix this by telling perltidy to ignore old blank lines by including the added parameter
-kbl=0 and rerunning. Then the unwanted blank lines will be gone. However, this will cause all old
blank lines to be ignored, perhaps even some that were added by hand to improve formatting. So please
be cautious when using these parameters.
-mbl=n --maximum-consecutive-blank-lines=n
This parameter specifies the maximum number of consecutive blank lines which will be output within
code sections of a script. The default is n=1. If the input file has more than n consecutive blank
lines, the number will be reduced to n except as noted above for the -blbp and -blbs parameters. If
n=0 then no blank lines will be output (unless all old blank lines are retained with the -kbl=2 flag
of the next section).
This flag obviously does not apply to pod sections, here-documents, and quotes.
-kbl=n, --keep-old-blank-lines=n
The -kbl=n flag gives you control over how your existing blank lines are treated.
The possible values of n are:
n=0 ignore all old blank lines
n=1 stable: keep old blanks, but limited by the value of the B<-mbl=n> flag
n=2 keep all old blank lines, regardless of the value of the B<-mbl=n> flag
The default is n=1.
-sob, --swallow-optional-blank-lines
This is equivalent to kbl=0 and is included for compatibility with previous versions.
-nsob, --noswallow-optional-blank-lines
This is equivalent to kbl=1 and is included for compatibility with previous versions.
Controls for blank lines around lines of consecutive keywords
The parameters in this section provide some control over the placement of blank lines within and around
groups of statements beginning with selected keywords. These blank lines are called here keyword group
blanks, and all of the parameters begin with --keyword-group-blanks*, or -kgb* for short. The default
settings do not employ these controls but they can be enabled with the following parameters:
-kgbl=s or --keyword-group-blanks-list=s; s is a quoted string of keywords
-kgbs=s or --keyword-group-blanks-size=s; s gives the number of keywords required to form a group.
-kgbb=n or --keyword-group-blanks-before=n; n = (0, 1, or 2) controls a leading blank
-kgba=n or --keyword-group-blanks-after=n; n = (0, 1, or 2) controls a trailing blank
-kgbi or --keyword-group-blanks-inside is a switch for adding blanks between subgroups
-kgbd or --keyword-group-blanks-delete is a switch for removing initial blank lines between keywords
-kgbr=n or --keyword-group-blanks-repeat-count=n can limit the number of times this logic is applied
In addition, the following abbreviations are available to for simplified usage:
-kgb or --keyword-group-blanks is short for -kgbb=2 -kgba=2 kgbi
-nkgb or --nokeyword-group-blanks, is short for -kgbb=1 -kgba=1 nkgbi
Before describing the meaning of the parameters in detail let us look at an example which is formatted
with default parameter settings.
print "Entering test 2\n";
use Test;
use Encode qw(from_to encode decode
encode_utf8 decode_utf8
find_encoding is_utf8);
use charnames qw(greek);
my @encodings = grep( /iso-?8859/, Encode::encodings() );
my @character_set = ( '0' .. '9', 'A' .. 'Z', 'a' .. 'z' );
my @source = qw(ascii iso8859-1 cp1250);
my @destiny = qw(cp1047 cp37 posix-bc);
my @ebcdic_sets = qw(cp1047 cp37 posix-bc);
my $str = join( '', map( chr($_), 0x20 .. 0x7E ) );
return unless ($str);
using perltidy -kgb gives:
print "Entering test 2\n";
<----------this blank controlled by -kgbb
use Test;
use Encode qw(from_to encode decode
encode_utf8 decode_utf8
find_encoding is_utf8);
use charnames qw(greek);
<---------this blank controlled by -kgbi
my @encodings = grep( /iso-?8859/, Encode::encodings() );
my @character_set = ( '0' .. '9', 'A' .. 'Z', 'a' .. 'z' );
my @source = qw(ascii iso8859-1 cp1250);
my @destiny = qw(cp1047 cp37 posix-bc);
my @ebcdic_sets = qw(cp1047 cp37 posix-bc);
my $str = join( '', map( chr($_), 0x20 .. 0x7E ) );
<----------this blank controlled by -kgba
return unless ($str);
Blank lines have been introduced around the my and use sequences. What happened is that the default
keyword list includes my and use but not print and return. So a continuous sequence of nine my and use
statements was located. This number exceeds the default threshold of five, so blanks were placed before
and after the entire group. Then, since there was also a subsequence of six my lines, a blank line was
introduced to separate them.
Finer control over blank placement can be achieved by using the individual parameters rather than the
-kgb flag. The individual controls are as follows.
-kgbl=s or --keyword-group-blanks-list=s, where s is a quoted string, defines the set of keywords which
will be formed into groups. The string is a space separated list of keywords. The default set is s="use
require local our my", but any list of keywords may be used. Comment lines may also be included in a
keyword group, even though they are not keywords. To include ordinary block comments, include the symbol
BC. To include static block comments (which normally begin with '##'), include the symbol SBC.
-kgbs=s or --keyword-group-blanks-size=s, where s is a string describing the number of consecutive
keyword statements forming a group. If s is an integer then it is the minimum number required for a
group. A maximum value may also be given with the format s=min.max, where min is the minimum number and
max is the maximum number, and the min and max values are separated by one or more dots. No groups will
be found if the maximum is less than the minimum. The maximum is unlimited if not given. The default is
s=5. Some examples:
s min max number for group
3 3 unlimited 3 or more
1.1 1 1 1
1..3 1 3 1 to 3
1.0 1 0 (no match)
-kgbb=n or --keyword-group-blanks-before=n specifies whether a blank should appear before the first line
of the group, as follows:
n=0 => (delete) an existing blank line will be removed
n=1 => (stable) no change to the input file is made [DEFAULT]
n=2 => (insert) a blank line is introduced if possible
-kgba=n or --keyword-group-blanks-after=n likewise specifies whether a blank should appear after the last
line of the group, using the same scheme (0=delete, 1=stable, 2=insert).
-kgbi or --keyword-group-blanks-inside controls the insertion of blank lines between the first and last
statement of the entire group. If there is a continuous run of a single statement type with more than
the minimum threshold number (as specified with -kgbs=s) then this switch causes a blank line be inserted
between this subgroup and the others. In the example above this happened between the use and my
statements.
-kgbd or --keyword-group-blanks-delete controls the deletion of any blank lines that exist in the the
group when it is first scanned. When statements are initially scanned, any existing blank lines are
included in the collection. Any such orignial blank lines will be deleted before any other insertions
are made when the parameter -kgbd is set. The default is not to do this, -nkgbd.
-kgbr=n or --keyword-group-blanks-repeat-count=n specifies n, the maximum number of times this logic will
be applied to any file. The special value n=0 is the same as n=infinity which means it will be applied
to an entire script [Default]. A value n=1 could be used to make it apply just one time for example.
This might be useful for adjusting just the use statements in the top part of a module for example.
-kgb or --keyword-group-blanks is an abbreviation equivalent to setting -kgbb=1 -kgba=1 -kgbi. This
turns on keyword group formatting with a set of default values.
-nkgb or --nokeyword-group-blanks is equivalent to -kgbb=0 -kgba nkgbi. This flag turns off keyword
group blank lines and is the default setting.
Here are a few notes about the functioning of this technique.
• These parameters are probably more useful as part of a major code reformatting operation rather than
as a routine formatting operation.
In particular, note that deleting old blank lines with -kgbd is an irreversible operation so it
should be applied with care. Existing blank lines may be serving an important role in controlling
vertical alignment.
• Conflicts which arise among these kgb* parameters and other blank line controls are generally
resolved by producing the maximum number of blank lines implied by any parameter.
For example, if the flags --freeze-blank-lines, or --keep-old-blank-lines=2, are set, then they have
priority over any blank line deletion implied by the -kgb flags of this section, so no blank lines
will be deleted.
For another example, if a keyword group ends at a sub and the flag kgba=0 requests no blank line
there, but we also have --blank-lines-before-subs=2, then two blank lines will still be introduced
before the sub.
• The introduction of blank lines does not occur if it would conflict with other input controls or code
validity. For example, a blank line will not be placed within a here-doc or within a section of code
marked with format skipping comments. And in general, a blank line will only be introduced at the
end of a group if the next statement is a line of code.
• The count which is used to determine the group size is not the number of lines but rather the total
number of keywords which are found. Individual statements with a certain leading keyword may
continue on multiple lines, but if any of these lines is nested more than one level deep then that
group will be ended.
• The search for groups of lines with similar leading keywords is based on the input source, not the
final formatted source. Consequently, if the source code is badly formatted, it would be best to
make a first formatting pass without these options.
Styles
A style refers to a convenient collection of existing parameters.
-gnu, --gnu-style
-gnu gives an approximation to the GNU Coding Standards (which do not apply to perl) as they are
sometimes implemented. At present, this style overrides the default style with the following
parameters:
-lp -bl -noll -pt=2 -bt=2 -sbt=2 -icp
-pbp, --perl-best-practices
-pbp is an abbreviation for the parameters in the book Perl Best Practices by Damian Conway:
-l=78 -i=4 -ci=4 -st -se -vt=2 -cti=0 -pt=1 -bt=1 -sbt=1 -bbt=1 -nsfs -nolq
-wbb="% + - * / x != == >= <= =~ !~ < > | & =
**= += *= &= <<= &&= -= /= |= >>= ||= //= .= %= ^= x="
Please note that this parameter set includes -st and -se flags, which make perltidy act as a filter
on one file only. These can be overridden by placing -nst and/or -nse after the -pbp parameter.
Also note that the value of continuation indentation, -ci=4, is equal to the value of the full
indentation, -i=4. It is recommended that the either (1) the parameter -ci=2 be used instead, or the
flag -xci be set. This will help show structure, particularly when there are ternary statements. The
following snippet illustrates these options.
# perltidy -pbp
$self->{_text} = (
!$section ? ''
: $type eq 'item' ? "the $section entry"
: "the section on $section"
)
. (
$page
? ( $section ? ' in ' : '' ) . "the $page$page_ext manpage"
: ' elsewhere in this document'
);
# perltidy -pbp -ci=2
$self->{_text} = (
!$section ? ''
: $type eq 'item' ? "the $section entry"
: "the section on $section"
)
. (
$page
? ( $section ? ' in ' : '' ) . "the $page$page_ext manpage"
: ' elsewhere in this document'
);
# perltidy -pbp -xci
$self->{_text} = (
!$section ? ''
: $type eq 'item' ? "the $section entry"
: "the section on $section"
)
. ( $page
? ( $section ? ' in ' : '' ) . "the $page$page_ext manpage"
: ' elsewhere in this document'
);
The -xci flag was developed after the -pbp parameters were published so you need to include it
separately.
One-line blocks
There are a few points to note regarding one-line blocks. A one-line block is something like this,
where the contents within the curly braces is short enough to fit on a single line.
With few exceptions, perltidy retains existing one-line blocks, if it is possible within the line-
length constraint, but it does not attempt to form new ones. In other words, perltidy will try to
follow the one-line block style of the input file.
If an existing one-line block is longer than the maximum line length, however, it will be broken into
multiple lines. When this happens, perltidy checks for and adds any optional terminating semicolon
(unless the -nasc option is used) if the block is a code block.
The main exception is that perltidy will attempt to form new one-line blocks following the keywords
"map", "eval", and "sort", because these code blocks are often small and most clearly displayed in a
single line.
One-line block rules can conflict with the cuddled-else option. When the cuddled-else option is
used, perltidy retains existing one-line blocks, even if they do not obey cuddled-else formatting.
Occasionally, when one-line blocks get broken because they exceed the available line length, the
formatting will violate the requested brace style. If this happens, reformatting the script a second
time should correct the problem.
Sometimes it might be desirable to convert a script to have one-line blocks whenever possible.
Although there is currently no flag for this, a simple workaround is to execute perltidy twice, once
with the flag -noadd-newlines and then once again with normal parameters, like this:
cat infile | perltidy -nanl | perltidy >outfile
When executed on this snippet
if ( $? == -1 ) {
die "failed to execute: $!\n";
}
if ( $? == -1 ) {
print "Had enough.\n";
die "failed to execute: $!\n";
}
the result is
if ( $? == -1 ) { die "failed to execute: $!\n"; }
if ( $? == -1 ) {
print "Had enough.\n";
die "failed to execute: $!\n";
}
This shows that blocks with a single statement become one-line blocks.
-olbs=n, --one-line-block-semicolons=n
This flag controls the placement of semicolons at the end of one-line blocks. Semicolons are
optional before a closing block brace, and frequently they are omitted at the end of a one-line block
containing just a single statement. By default, perltidy follows the input file regarding these
semicolons, but this behavior can be controlled by this flag. The values of n are:
n=0 remove terminal semicolons in one-line blocks having a single statement
n=1 stable; keep input file placement of terminal semicolons [DEFAULT ]
n=2 add terminal semicolons in all one-line blocks
Note that the n=2 option has no effect if adding semicolons is prohibited with the -nasc flag. Also
not that while n=2 adds missing semicolons to all one-line blocks, regardless of complexity, the n=0
option only removes ending semicolons which terminate one-line blocks containing just one semicolon.
So these two options are not exact inverses.
-olbn=n, --one-line-block-nesting=n
Nested one-line blocks are lines with code blocks which themselves contain code blocks. For example,
the following line is a nested one-line block.
foreach (@list) { if ($_ eq $asked_for) { last } ++$found }
The default behavior is to break such lines into multiple lines, but this behavior can be controlled
with this flag. The values of n are:
n=0 break nested one-line blocks into multiple lines [DEFAULT]
n=1 stable: keep existing nested-one line blocks intact
For the above example, the default formatting (-olbn=0) is
foreach (@list) {
if ( $_ eq $asked_for ) { last }
++$found;
}
If the parameter -olbn=1 is given, then the line will be left intact if it is a single line in the
source, or it will be broken into multiple lines if it is broken in multiple lines in the source.
Controlling Vertical Alignment
Vertical alignment refers to lining up certain symbols in a list of consecutive similar lines to improve
readability. For example, the "fat commas" are aligned in the following statement:
$data = $pkg->new(
PeerAddr => join( ".", @port[ 0 .. 3 ] ),
PeerPort => $port[4] * 256 + $port[5],
Proto => 'tcp'
);
Vertical alignment can be completely turned off using -novalign, a flag mainly intended for debugging.
However, vertical alignment can be forced to stop and restart by selectively introducing blank lines.
For example, a blank has been inserted in the following code to keep somewhat similar things aligned.
%option_range = (
'format' => [ 'tidy', 'html', 'user' ],
'output-line-ending' => [ 'dos', 'win', 'mac', 'unix' ],
'character-encoding' => [ 'none', 'utf8' ],
'block-brace-tightness' => [ 0, 2 ],
'brace-tightness' => [ 0, 2 ],
'paren-tightness' => [ 0, 2 ],
'square-bracket-tightness' => [ 0, 2 ],
);
Vertical alignment is implemented by locally increasing an existing blank space to produce alignment with
an adjacent line. It cannot occur if there is no blank space to increase. So if a particular space is
removed by one of the existing controls then vertical alignment cannot occur. Likewise, if a space is
added with one of the controls, then vertical alignment might occur.
For example,
# perltidy -nwls='=>'
$data = $pkg->new(
PeerAddr=> join( ".", @port[ 0 .. 3 ] ),
PeerPort=> $port[4] * 256 + $port[5],
Proto=> 'tcp'
);
Other Controls
Deleting selected text
Perltidy can selectively delete comments and/or pod documentation. The command -dac or
--delete-all-comments will delete all comments and all pod documentation, leaving just code and any
leading system control lines.
The command -dp or --delete-pod will remove all pod documentation (but not comments).
Two commands which remove comments (but not pod) are: -dbc or --delete-block-comments and -dsc or
--delete-side-comments. (Hanging side comments will be deleted with side comments here.)
The negatives of these commands also work, and are the defaults. When block comments are deleted,
any leading 'hash-bang' will be retained. Also, if the -x flag is used, any system commands before a
leading hash-bang will be retained (even if they are in the form of comments).
Writing selected text to a file
When perltidy writes a formatted text file, it has the ability to also send selected text to a file
with a .TEE extension. This text can include comments and pod documentation.
The command -tac or --tee-all-comments will write all comments and all pod documentation.
The command -tp or --tee-pod will write all pod documentation (but not comments).
The commands which write comments (but not pod) are: -tbc or --tee-block-comments and -tsc or
--tee-side-comments. (Hanging side comments will be written with side comments here.)
The negatives of these commands also work, and are the defaults.
Using a .perltidyrc command file
If you use perltidy frequently, you probably won't be happy until you create a .perltidyrc file to
avoid typing commonly-used parameters. Perltidy will first look in your current directory for a
command file named .perltidyrc. If it does not find one, it will continue looking for one in other
standard locations.
These other locations are system-dependent, and may be displayed with the command "perltidy -dpro".
Under Unix systems, it will first look for an environment variable PERLTIDY. Then it will look for a
.perltidyrc file in the home directory, and then for a system-wide file /usr/local/etc/perltidyrc,
and then it will look for /etc/perltidyrc. Note that these last two system-wide files do not have a
leading dot. Further system-dependent information will be found in the INSTALL file distributed with
perltidy.
Under Windows, perltidy will also search for a configuration file named perltidy.ini since Windows
does not allow files with a leading period (.). Use "perltidy -dpro" to see the possible locations
for your system. An example might be C:\Documents and Settings\All Users\perltidy.ini.
Another option is the use of the PERLTIDY environment variable. The method for setting environment
variables depends upon the version of Windows that you are using. Instructions for Windows 95 and
later versions can be found here:
http://www.netmanage.com/000/20021101_005_tcm21-6336.pdf
Under Windows NT / 2000 / XP the PERLTIDY environment variable can be placed in either the user
section or the system section. The later makes the configuration file common to all users on the
machine. Be sure to enter the full path of the configuration file in the value of the environment
variable. Ex. PERLTIDY=C:\Documents and Settings\perltidy.ini
The configuration file is free format, and simply a list of parameters, just as they would be entered
on a command line. Any number of lines may be used, with any number of parameters per line, although
it may be easiest to read with one parameter per line. Comment text begins with a #, and there must
also be a space before the # for side comments. It is a good idea to put complex parameters in
either single or double quotes.
Here is an example of a .perltidyrc file:
# This is a simple of a .perltidyrc configuration file
# This implements a highly spaced style
-se # errors to standard error output
-w # show all warnings
-bl # braces on new lines
-pt=0 # parens not tight at all
-bt=0 # braces not tight
-sbt=0 # square brackets not tight
The parameters in the .perltidyrc file are installed first, so any parameters given on the command
line will have priority over them.
To avoid confusion, perltidy ignores any command in the .perltidyrc file which would cause some kind
of dump and an exit. These are:
-h -v -ddf -dln -dop -dsn -dtt -dwls -dwrs -ss
There are several options may be helpful in debugging a .perltidyrc file:
• A very helpful command is --dump-profile or -dpro. It writes a list of all configuration
filenames tested to standard output, and if a file is found, it dumps the content to standard
output before exiting. So, to find out where perltidy looks for its configuration files, and
which one if any it selects, just enter
perltidy -dpro
• It may be simplest to develop and test configuration files with alternative names, and invoke
them with -pro=filename on the command line. Then rename the desired file to .perltidyrc when
finished.
• The parameters in the .perltidyrc file can be switched off with the -npro option.
• The commands --dump-options, --dump-defaults, --dump-long-names, and --dump-short-names, all
described below, may all be helpful.
Creating a new abbreviation
A special notation is available for use in a .perltidyrc file for creating an abbreviation for a
group of options. This can be used to create a shorthand for one or more styles which are
frequently, but not always, used. The notation is to group the options within curly braces which are
preceded by the name of the alias (without leading dashes), like this:
newword {
-opt1
-opt2
}
where newword is the abbreviation, and opt1, etc, are existing parameters or other abbreviations.
The main syntax requirement is that the new abbreviation along with its opening curly brace must
begin on a new line. Space before and after the curly braces is optional.
For a specific example, the following line
oneliner { --maximum-line-length=0 --noadd-newlines --noadd-terminal-newline}
or equivalently with abbreviations
oneliner { -l=0 -nanl -natnl }
could be placed in a .perltidyrc file to temporarily override the maximum line length with a large
value, to temporarily prevent new line breaks from being added, and to prevent an extra newline
character from being added the file. All other settings in the .perltidyrc file still apply. Thus
it provides a way to format a long 'one liner' when perltidy is invoked with
perltidy --oneliner ...
(Either "-oneliner" or "--oneliner" may be used).
Skipping leading non-perl commands with -x or --look-for-hash-bang
If your script has leading lines of system commands or other text which are not valid perl code, and
which are separated from the start of the perl code by a "hash-bang" line, ( a line of the form
"#!...perl" ), you must use the -x flag to tell perltidy not to parse and format any lines before the
"hash-bang" line. This option also invokes perl with a -x flag when checking the syntax. This
option was originally added to allow perltidy to parse interactive VMS scripts, but it should be used
for any script which is normally invoked with "perl -x".
Please note: do not use this flag unless you are sure your script needs it. Parsing errors can occur
if it does not have a hash-bang, or, for example, if the actual first hash-bang is in a here-doc. In
that case a parsing error will occur because the tokenization will begin in the middle of the here-
doc.
Making a file unreadable
The goal of perltidy is to improve the readability of files, but there are two commands which have
the opposite effect, --mangle and --extrude. They are actually merely aliases for combinations of
other parameters. Both of these strip all possible whitespace, but leave comments and pod documents,
so that they are essentially reversible. The difference between these is that --mangle puts the
fewest possible line breaks in a script while --extrude puts the maximum possible. Note that these
options do not provided any meaningful obfuscation, because perltidy can be used to reformat the
files. They were originally developed to help test the tokenization logic of perltidy, but they have
other uses. One use for --mangle is the following:
perltidy --mangle myfile.pl -st | perltidy -o myfile.pl.new
This will form the maximum possible number of one-line blocks (see next section), and can sometimes
help clean up a badly formatted script.
A similar technique can be used with --extrude instead of --mangle to make the minimum number of one-
line blocks.
Another use for --mangle is to combine it with -dac to reduce the file size of a perl script.
Debugging
The following flags are available for debugging:
--dump-cuddled-block-list or -dcbl will dump to standard output the internal hash of cuddled block
types created by a -cuddled-block-list input string.
--dump-defaults or -ddf will write the default option set to standard output and quit
--dump-profile or -dpro will write the name of the current configuration file and its contents to
standard output and quit.
--dump-options or -dop will write current option set to standard output and quit.
--dump-long-names or -dln will write all command line long names (passed to Get_options) to standard
output and quit.
--dump-short-names or -dsn will write all command line short names to standard output and quit.
--dump-token-types or -dtt will write a list of all token types to standard output and quit.
--dump-want-left-space or -dwls will write the hash %want_left_space to standard output and quit.
See the section on controlling whitespace around tokens.
--dump-want-right-space or -dwrs will write the hash %want_right_space to standard output and quit.
See the section on controlling whitespace around tokens.
--no-memoize or -nmem will turn of memoizing. Memoization can reduce run time when running perltidy
repeatedly in a single process. It is on by default but can be deactivated for testing with -nmem.
--no-timestamp or -nts will eliminate any time stamps in output files to prevent differences in dates
from causing test installation scripts to fail. There are just a couple of places where timestamps
normally occur. One is in the headers of html files, and another is when the -cscw option is
selected. The default is to allow timestamps (--timestamp or -ts).
--file-size-order or -fso will cause files to be processed in order of increasing size, when multiple
files are being processed. This is useful during program development, when large numbers of files
with varying sizes are processed, because it can reduce virtual memory usage.
--maximum-file-size-mb=n or -maxfs=n specifies the maximum file size in megabytes that perltidy will
attempt to format. This parameter is provided to avoid causing system problems by accidentally
attempting to format an extremely large data file. Most perl scripts are less than about 2 MB in
size. The integer n has a default value of 10, so perltidy will skip formatting files which have a
size greater than 10 MB. The command to increase the limit to 20 MB for example would be
perltidy -maxfs=20
This only applies to files specified by filename on the command line.
--maximum-level-errors=n or -maxle=n specifies the maximum number of indentation level errors are
allowed before perltidy skips formatting and just outputs a file verbatim. The default is n=1. This
means that if the final indentation of a script differs from the starting indentation by more than 1
levels, the file will be output verbatim. To avoid formatting if there are any indentation level
errors use -maxle=0. To skip this check you can either set n equal to a large number, such as n=100,
or set n=-1.
For example, the following script has level error of 3 and will be output verbatim
Input and default output:
{{{
perltidy -maxle=100
{
{
{
--maximum-unexpected-errors=n or -maxue=n specifies the maximum number of unexpected tokenization
errors are allowed before formatting is skipped and a script is output verbatim. The intention is to
avoid accidentally formatting a non-perl script, such as an html file for example. This check can be
turned off by setting n=0.
A recommended value is n=3. However, the default is n=0 (skip this check) to avoid causing problems
with scripts which have extended syntaxes.
-DEBUG will write a file with extension .DEBUG for each input file showing the tokenization of all
lines of code.
Working with MakeMaker, AutoLoader and SelfLoader
The first $VERSION line of a file which might be eval'd by MakeMaker is passed through unchanged
except for indentation. Use --nopass-version-line, or -npvl, to deactivate this feature.
If the AutoLoader module is used, perltidy will continue formatting code after seeing an __END__
line. Use --nolook-for-autoloader, or -nlal, to deactivate this feature.
Likewise, if the SelfLoader module is used, perltidy will continue formatting code after seeing a
__DATA__ line. Use --nolook-for-selfloader, or -nlsl, to deactivate this feature.
Working around problems with older version of Perl
Perltidy contains a number of rules which help avoid known subtleties and problems with older
versions of perl, and these rules always take priority over whatever formatting flags have been set.
For example, perltidy will usually avoid starting a new line with a bareword, because this might
cause problems if "use strict" is active.
There is no way to override these rules.
HTML OPTIONS
The -html master switch
The flag -html causes perltidy to write an html file with extension .html. So, for example, the
following command
perltidy -html somefile.pl
will produce a syntax-colored html file named somefile.pl.html which may be viewed with a browser.
Please Note: In this case, perltidy does not do any formatting to the input file, and it does not
write a formatted file with extension .tdy. This means that two perltidy runs are required to create
a fully reformatted, html copy of a script.
The -pre flag for code snippets
When the -pre flag is given, only the pre-formatted section, within the <PRE> and </PRE> tags, will
be output. This simplifies inclusion of the output in other files. The default is to output a
complete web page.
The -nnn flag for line numbering
When the -nnn flag is given, the output lines will be numbered.
The -toc, or --html-table-of-contents flag
By default, a table of contents to packages and subroutines will be written at the start of html
output. Use -ntoc to prevent this. This might be useful, for example, for a pod document which
contains a number of unrelated code snippets. This flag only influences the code table of contents;
it has no effect on any table of contents produced by pod2html (see next item).
The -pod, or --pod2html flag
There are two options for formatting pod documentation. The default is to pass the pod through the
Pod::Html module (which forms the basis of the pod2html utility). Any code sections are formatted by
perltidy, and the results then merged. Note: perltidy creates a temporary file when Pod::Html is
used; see "FILES". Also, Pod::Html creates temporary files for its cache.
NOTE: Perltidy counts the number of "=cut" lines, and either moves the pod text to the top of the
html file if there is one "=cut", or leaves the pod text in its original order (interleaved with
code) otherwise.
Most of the flags accepted by pod2html may be included in the perltidy command line, and they will be
passed to pod2html. In some cases, the flags have a prefix "pod" to emphasize that they are for the
pod2html, and this prefix will be removed before they are passed to pod2html. The flags which have
the additional "pod" prefix are:
--[no]podheader --[no]podindex --[no]podrecurse --[no]podquiet
--[no]podverbose --podflush
The flags which are unchanged from their use in pod2html are:
--backlink=s --cachedir=s --htmlroot=s --libpods=s --title=s
--podpath=s --podroot=s
where 's' is an appropriate character string. Not all of these flags are available in older versions
of Pod::Html. See your Pod::Html documentation for more information.
The alternative, indicated with -npod, is not to use Pod::Html, but rather to format pod text in
italics (or whatever the stylesheet indicates), without special html markup. This is useful, for
example, if pod is being used as an alternative way to write comments.
The -frm, or --frames flag
By default, a single html output file is produced. This can be changed with the -frm option, which
creates a frame holding a table of contents in the left panel and the source code in the right side.
This simplifies code browsing. Assume, for example, that the input file is MyModule.pm. Then, for
default file extension choices, these three files will be created:
MyModule.pm.html - the frame
MyModule.pm.toc.html - the table of contents
MyModule.pm.src.html - the formatted source code
Obviously this file naming scheme requires that output be directed to a real file (as opposed to,
say, standard output). If this is not the case, or if the file extension is unknown, the -frm option
will be ignored.
The -text=s, or --html-toc-extension flag
Use this flag to specify the extra file extension of the table of contents file when html frames are
used. The default is "toc". See "Specifying File Extensions".
The -sext=s, or --html-src-extension flag
Use this flag to specify the extra file extension of the content file when html frames are used. The
default is "src". See "Specifying File Extensions".
The -hent, or --html-entities flag
This flag controls the use of Html::Entities for html formatting. By default, the module
Html::Entities is used to encode special symbols. This may not be the right thing for some
browser/language combinations. Use --nohtml-entities or -nhent to prevent this.
Style Sheets
Style sheets make it very convenient to control and adjust the appearance of html pages. The default
behavior is to write a page of html with an embedded style sheet.
An alternative to an embedded style sheet is to create a page with a link to an external style sheet.
This is indicated with the -css=filename, where the external style sheet is filename. The external
style sheet filename will be created if and only if it does not exist. This option is useful for
controlling multiple pages from a single style sheet.
To cause perltidy to write a style sheet to standard output and exit, use the -ss, or --stylesheet,
flag. This is useful if the style sheet could not be written for some reason, such as if the -pre
flag was used. Thus, for example,
perltidy -html -ss >mystyle.css
will write a style sheet with the default properties to file mystyle.css.
The use of style sheets is encouraged, but a web page without a style sheets can be created with the
flag -nss. Use this option if you must to be sure that older browsers (roughly speaking, versions
prior to 4.0 of Netscape Navigator and Internet Explorer) can display the syntax-coloring of the html
files.
Controlling HTML properties
Note: It is usually more convenient to accept the default properties and then edit the stylesheet
which is produced. However, this section shows how to control the properties with flags to perltidy.
Syntax colors may be changed from their default values by flags of the either the long form,
-html-color-xxxxxx=n, or more conveniently the short form, -hcx=n, where xxxxxx is one of the
following words, and x is the corresponding abbreviation:
Token Type xxxxxx x
---------- -------- --
comment comment c
number numeric n
identifier identifier i
bareword, function bareword w
keyword keyword k
quite, pattern quote q
here doc text here-doc-text h
here doc target here-doc-target hh
punctuation punctuation pu
parentheses paren p
structural braces structure s
semicolon semicolon sc
colon colon co
comma comma cm
label label j
sub definition name subroutine m
pod text pod-text pd
A default set of colors has been defined, but they may be changed by providing values to any of the
following parameters, where n is either a 6 digit hex RGB color value or an ascii name for a color,
such as 'red'.
To illustrate, the following command will produce an html file somefile.pl.html with "aqua" keywords:
perltidy -html -hck=00ffff somefile.pl
and this should be equivalent for most browsers:
perltidy -html -hck=aqua somefile.pl
Perltidy merely writes any non-hex names that it sees in the html file. The following 16 color names
are defined in the HTML 3.2 standard:
black => 000000,
silver => c0c0c0,
gray => 808080,
white => ffffff,
maroon => 800000,
red => ff0000,
purple => 800080,
fuchsia => ff00ff,
green => 008000,
lime => 00ff00,
olive => 808000,
yellow => ffff00
navy => 000080,
blue => 0000ff,
teal => 008080,
aqua => 00ffff,
Many more names are supported in specific browsers, but it is safest to use the hex codes for other
colors. Helpful color tables can be located with an internet search for "HTML color tables".
Besides color, two other character attributes may be set: bold, and italics. To set a token type to
use bold, use the flag --html-bold-xxxxxx or -hbx, where xxxxxx or x are the long or short names from
the above table. Conversely, to set a token type to NOT use bold, use --nohtml-bold-xxxxxx or -nhbx.
Likewise, to set a token type to use an italic font, use the flag --html-italic-xxxxxx or -hix, where
again xxxxxx or x are the long or short names from the above table. And to set a token type to NOT
use italics, use --nohtml-italic-xxxxxx or -nhix.
For example, to use bold braces and lime color, non-bold, italics keywords the following command
would be used:
perltidy -html -hbs -hck=00FF00 -nhbk -hik somefile.pl
The background color can be specified with --html-color-background=n, or -hcbg=n for short, where n
is a 6 character hex RGB value. The default color of text is the value given to punctuation, which
is black as a default.
Here are some notes and hints:
1. If you find a preferred set of these parameters, you may want to create a .perltidyrc file
containing them. See the perltidy man page for an explanation.
2. Rather than specifying values for these parameters, it is probably easier to accept the defaults
and then edit a style sheet. The style sheet contains comments which should make this easy.
3. The syntax-colored html files can be very large, so it may be best to split large files into
smaller pieces to improve download times.
SOME COMMON INPUT CONVENTIONS
Specifying Block Types
Several parameters which refer to code block types may be customized by also specifying an associated
list of block types. The type of a block is the name of the keyword which introduces that block, such as
if, else, or sub. An exception is a labeled block, which has no keyword, and should be specified with
just a colon. To specify all blocks use '*'.
The keyword sub indicates a named sub. For anonymous subs, use the special keyword asub.
For example, the following parameter specifies "sub", labels, "BEGIN", and "END" blocks:
-cscl="sub : BEGIN END"
(the meaning of the -cscl parameter is described above.) Note that quotes are required around the list
of block types because of the spaces. For another example, the following list specifies all block types
for vertical tightness:
-bbvtl='*'
Specifying File Extensions
Several parameters allow default file extensions to be overridden. For example, a backup file extension
may be specified with -bext=ext, where ext is some new extension. In order to provides the user some
flexibility, the following convention is used in all cases to decide if a leading '.' should be used. If
the extension "ext" begins with "A-Z", "a-z", or "0-9", then it will be appended to the filename with an
intermediate '.' (or perhaps a '_' on VMS systems). Otherwise, it will be appended directly.
For example, suppose the file is somefile.pl. For "-bext=old", a '.' is added to give somefile.pl.old.
For "-bext=.old", no additional '.' is added, so again the backup file is somefile.pl.old. For
"-bext=~", then no dot is added, and the backup file will be somefile.pl~ .
SWITCHES WHICH MAY BE NEGATED
The following list shows all short parameter names which allow a prefix 'n' to produce the negated form:
D anl asbl asc ast asu atnl aws b baa
baao bar bbao bbb bbc bbs bl bli boa boc
bok bol bom bos bot cblx ce conv cs csc
cscb cscw dac dbc dcbl dcsc ddf dln dnl dop
dp dpro dsc dsm dsn dtt dwls dwrs dws f
fll fpva frm fs fso gcs hbc hbcm hbco hbh
hbhh hbi hbj hbk hbm hbn hbp hbpd hbpu hbq
hbs hbsc hbv hbw hent hic hicm hico hih hihh
hii hij hik him hin hip hipd hipu hiq his
hisc hiv hiw hsc html ibc icb icp iob isbc
iscl kgb kgbd kgbi kis lal log lop lp lsl
mem nib ohbr okw ola olc oll olq opr opt
osbc osbr otr ple pod pvl q sac sbc sbl
scbb schb scp scsb sct se sfp sfs skp sob
sobb sohb sop sosb sot ssc st sts t tac
tbc toc tp tqw trp ts tsc tso vmll w
wn x xci xs
Equivalently, the prefix 'no' or 'no-' on the corresponding long names may be used.
LIMITATIONS
Parsing Limitations
Perltidy should work properly on most perl scripts. It does a lot of self-checking, but still, it is
possible that an error could be introduced and go undetected. Therefore, it is essential to make
careful backups and to test reformatted scripts.
The main current limitation is that perltidy does not scan modules included with 'use' statements.
This makes it necessary to guess the context of any bare words introduced by such modules. Perltidy
has good guessing algorithms, but they are not infallible. When it must guess, it leaves a message
in the log file.
If you encounter a bug, please report it.
What perltidy does not parse and format
Perltidy indents but does not reformat comments and "qw" quotes. Perltidy does not in any way modify
the contents of here documents or quoted text, even if they contain source code. (You could,
however, reformat them separately). Perltidy does not format 'format' sections in any way. And, of
course, it does not modify pod documents.
FILES
Temporary files
Under the -html option with the default --pod2html flag, a temporary file is required to pass text to
Pod::Html. Unix systems will try to use the POSIX tmpnam() function. Otherwise the file
perltidy.TMP will be temporarily created in the current working directory.
Special files when standard input is used
When standard input is used, the log file, if saved, is perltidy.LOG, and any errors are written to
perltidy.ERR unless the -se flag is set. These are saved in the current working directory.
Files overwritten
The following file extensions are used by perltidy, and files with these extensions may be
overwritten or deleted: .ERR, .LOG, .TEE, and/or .tdy, .html, and .bak, depending on the run type and
settings.
Files extensions limitations
Perltidy does not operate on files for which the run could produce a file with a duplicated file
extension. These extensions include .LOG, .ERR, .TEE, and perhaps .tdy and .bak, depending on the
run type. The purpose of this rule is to prevent generating confusing filenames such as
somefile.tdy.tdy.tdy.
ERROR HANDLING
An exit value of 0, 1, or 2 is returned by perltidy to indicate the status of the result.
A exit value of 0 indicates that perltidy ran to completion with no error messages.
A non-zero exit value indicates some kind of problem was detected.
An exit value of 1 indicates that perltidy terminated prematurely, usually due to some kind of errors in
the input parameters. This can happen for example if a parameter is misspelled or given an invalid
value. Error messages in the standard error output will indicate the cause of any problem. If perltidy
terminates prematurely then no output files will be produced.
An exit value of 2 indicates that perltidy was able to run to completion but there there are (1) warning
messages in the standard error output related to parameter errors or problems and/or (2) warning messages
in the perltidy error file(s) relating to possible syntax errors in one or more of the source script(s)
being tidied. When multiple files are being processed, an error detected in any single file will produce
this type of exit condition.
SEE ALSO
perlstyle(1), Perl::Tidy(3)
INSTALLATION
The perltidy binary uses the Perl::Tidy module and is installed when that module is installed. The
module name is case-sensitive. For example, the basic command for installing with cpanm is 'cpanm
Perl::Tidy'.
VERSION
This man page documents perltidy version 20210717
BUG REPORTS
A list of current bugs and issues can be found at the CPAN site
<https://rt.cpan.org/Public/Dist/Display.html?Name=Perl-Tidy>
To report a new bug or problem, use the link on this page.
The source code repository is at <https://github.com/perltidy/perltidy>.
COPYRIGHT
Copyright (c) 2000-2021 by Steve Hancock
LICENSE
This package is free software; you can redistribute it and/or modify it under the terms of the "GNU
General Public License".
Please refer to the file "COPYING" for details.
DISCLAIMER
This package is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the "GNU General Public License" for more details.
perl v5.32.1 2021-10-24 PERLTIDY(1p)