Provided by: perl-doc_5.40.1-5_all 
NAME
CPAN::Meta::History::Meta_1_4 - Version 1.4 metadata specification for META.yml
PREFACE
This is a historical copy of the version 1.4 specification for META.yml files, copyright by Ken Williams
and licensed under the same terms as Perl itself.
Modifications from the original:
• Various spelling corrections
• Include list of valid licenses from Module::Build 0.2807 rather than linking to the module, with
minor updates to text and links to reflect versions at the time of publication.
• Fixed some dead links to point to active resources.
SYNOPSIS
--- #YAML:1.0
name: Module-Build
abstract: Build and install Perl modules
version: 0.20
author:
- Ken Williams <kwilliams@cpan.org>
license: perl
distribution_type: module
requires:
Config: 0
Cwd: 0
Data::Dumper: 0
ExtUtils::Install: 0
File::Basename: 0
File::Compare: 0
File::Copy: 0
File::Find: 0
File::Path: 0
File::Spec: 0
IO::File: 0
perl: 5.005_03
recommends:
Archive::Tar: 1.00
ExtUtils::Install: 0.3
ExtUtils::ParseXS: 2.02
Pod::Text: 0
YAML: 0.35
build_requires:
Test: 0
resources:
license: http://dev.perl.org/licenses/
meta-spec:
version: 1.4
url: http://module-build.sourceforge.net/META-spec-v1.3.html
generated_by: Module::Build version 0.20
DESCRIPTION
This document describes version 1.4 of the META.yml specification.
The META.yml file describes important properties of contributed Perl distributions such as the ones found
on CPAN. It is typically created by tools like Module::Build, Module::Install, and ExtUtils::MakeMaker.
The fields in the META.yml file are meant to be helpful for people maintaining module collections (like
CPAN), for people writing installation tools (like CPAN.pm or CPANPLUS), or just for people who want to
know some stuff about a distribution before downloading it and starting to install it.
Note: The latest stable version of this specification can always be found at
<http://module-build.sourceforge.net/META-spec-current.html>, and the latest development version (which
may include things that won't make it into the stable version) can always be found at
<http://module-build.sourceforge.net/META-spec-blead.html>.
FORMAT
META.yml files are written in the YAML format (see <http://www.yaml.org/>).
See the following links to learn why we chose YAML instead of, say, XML or Data::Dumper:
• Module::Build design plans <http://www.nntp.perl.org/group/perl.makemaker/2002/04/msg407.html>
• Not keen on YAML <http://www.nntp.perl.org/group/perl.module-authors/2003/11/msg1353.html>
• META Concerns <http://www.nntp.perl.org/group/perl.module-authors/2003/11/msg1385.html>
TERMINOLOGY
distribution
This is the primary object described by the META.yml specification. In the context of this document
it usually refers to a collection of modules, scripts, and/or documents that are distributed together
for other developers to use. Examples of distributions are "Class-Container", "libwww-perl", or
"DBI".
module
This refers to a reusable library of code typically contained in a single file. Currently, we
primarily talk of perl modules, but this specification should be open enough to apply to other
languages as well (ex. python, ruby). Examples of modules are "Class::Container", "LWP::Simple", or
"DBD::File".
HEADER
The first line of a META.yml file should be a valid YAML document header like "--- #YAML:1.0".
FIELDS
The rest of the META.yml file is one big YAML mapping whose keys are described here.
meta-spec
Example:
meta-spec:
version: 1.4
url: http://module-build.sourceforge.net/META-spec-v1.3.html
(Spec 1.1) [required] {URL} This field indicates the location of the version of the META.yml
specification used.
name
Example:
name: Module-Build
(Spec 1.0) [required] {string} The name of the distribution which is often created by taking the "main
module" in the distribution and changing "::" to "-". Sometimes it's completely different, however, as
in the case of the libwww-perl distribution (see <http://search.cpan.org/dist/libwww-perl/>).
version
Example:
version: 0.20
(Spec 1.0) [required] {version} The version of the distribution to which the META.yml file refers.
abstract
Example:
abstract: Build and install Perl modules.
(Spec 1.1) [required] {string} A short description of the purpose of the distribution.
author
Example:
author:
- Ken Williams <kwilliams@cpan.org>
(Spec 1.1) [required] {list of strings} A YAML sequence indicating the author(s) of the distribution. The
preferred form is author-name <email-address>.
license
Example:
license: perl
(Spec 1.0) [required] {string} The license under which this distribution may be used and redistributed.
Must be one of the following licenses:
apache
The distribution is licensed under the Apache Software License version 1.1
(<http://opensource.org/licenses/Apache-1.1>).
artistic
The distribution is licensed under the Artistic License version 1, as specified by the Artistic file
in the standard perl distribution (<http://opensource.org/licenses/Artistic-Perl-1.0>).
bsd The distribution is licensed under the BSD 3-Clause License
(<http://opensource.org/licenses/BSD-3-Clause>).
gpl The distribution is distributed under the terms of the GNU General Public License version 2
(<http://opensource.org/licenses/GPL-2.0>).
lgpl
The distribution is distributed under the terms of the GNU Lesser General Public License version 2
(<http://opensource.org/licenses/LGPL-2.1>).
mit The distribution is licensed under the MIT License (<http://opensource.org/licenses/MIT>).
mozilla
The distribution is licensed under the Mozilla Public License.
(<http://opensource.org/licenses/MPL-1.0> or <http://opensource.org/licenses/MPL-1.1>)
open_source
The distribution is licensed under some other Open Source Initiative-approved license listed at
<http://www.opensource.org/licenses/>.
perl
The distribution may be copied and redistributed under the same terms as perl itself (this is by far
the most common licensing option for modules on CPAN). This is a dual license, in which the user may
choose between either the GPL or the Artistic license.
restrictive
The distribution may not be redistributed without special permission from the author and/or copyright
holder.
unrestricted
The distribution is licensed under a license that is not approved by www.opensource.org
<http://www.opensource.org/> but that allows distribution without restrictions.
distribution_type
Example:
distribution_type: module
(Spec 1.0) [optional] {string} What kind of stuff is contained in this distribution. Most things on CPAN
are "module"s (which can also mean a collection of modules), but some things are "script"s.
Unfortunately this field is basically meaningless, since many distributions are hybrids of several kinds
of things, or some new thing, or subjectively different in focus depending on who's using them. Tools
like Module::Build and MakeMaker will likely stop generating this field.
requires
Example:
requires:
Data::Dumper: 0
File::Find: 1.03
(Spec 1.0) [optional] {map} A YAML mapping indicating the Perl prerequisites this distribution requires
for proper operation. The keys are the names of the prerequisites (module names or 'perl'), and the
values are version specifications as described in VERSION SPECIFICATIONS.
recommends
Example:
recommends:
Data::Dumper: 0
File::Find: 1.03
(Spec 1.0) [optional] {map} A YAML mapping indicating the Perl prerequisites this distribution recommends
for enhanced operation. The keys are the names of the prerequisites (module names or 'perl'), and the
values are version specifications as described in VERSION SPECIFICATIONS.
ALTERNATIVE: It may be desirable to present to the user which features depend on which modules so they
can make an informed decision about which recommended modules to install.
Example:
optional_features:
foo:
description: Provides the ability to blah.
requires:
Data::Dumper: 0
File::Find: 1.03
(Spec 1.1) [optional] {map} A YAML mapping of names for optional features which are made available when
its requirements are met. For each feature a description is provided along with any of "requires",
"build_requires", and "conflicts", which have the same meaning in this subcontext as described elsewhere
in this document.
build_requires
Example:
build_requires:
Data::Dumper: 0
File::Find: 1.03
(Spec 1.0) [optional] {map} A YAML mapping indicating the Perl prerequisites required for building and/or
testing of this distribution. The keys are the names of the prerequisites (module names or 'perl'), and
the values are version specifications as described in "VERSION SPECIFICATIONS". These dependencies are
not required after the distribution is installed.
configure_requires
Example:
configure_requires:
Module::Build: 0.2809
Data::Dumper: 0
File::Find: 1.03
(Spec 1.4) [optional] {map} A YAML mapping indicating the Perl prerequisites required before configuring
this distribution. The keys are the names of the prerequisites (module names or 'perl'), and the values
are version specifications as described in "VERSION SPECIFICATIONS". These dependencies are not required
after the distribution is installed.
conflicts
Example:
conflicts:
Data::Dumper: 0
File::Find: 1.03
(Spec 1.0) [optional] {map} A YAML mapping indicating any items that cannot be installed while this
distribution is installed. This is a pretty uncommon situation. The keys for "conflicts" are the item
names (module names or 'perl'), and the values are version specifications as described in "VERSION
SPECIFICATIONS".
dynamic_config
Example:
dynamic_config: 0
(Spec 1.0) [optional] {boolean} A boolean flag indicating whether a Build.PL or Makefile.PL (or similar)
must be executed when building this distribution, or whether it can be built, tested and installed solely
from consulting its metadata file. The main reason to set this to a true value is that your module
performs some dynamic configuration (asking questions, sensing the environment, etc.) as part of its
build/install process.
Currently Module::Build doesn't actually do anything with this flag - it's probably going to be up to
higher-level tools like CPAN to do something useful with it. It can potentially bring lots of security,
packaging, and convenience improvements.
If this field is omitted, it defaults to 1 (true).
private
(Deprecated) (Spec 1.0) [optional] {map} This field has been renamed to "no_index". See below.
provides
Example:
provides:
Foo::Bar:
file: lib/Foo/Bar.pm
version: 0.27_02
Foo::Bar::Blah:
file: lib/Foo/Bar/Blah.pm
Foo::Bar::Baz:
file: lib/Foo/Bar/Baz.pm
version: 0.3
(Spec 1.1) [optional] {map} A YAML mapping that describes all packages provided by this distribution.
This information can be (and, in some cases, is) used by distribution and automation mechanisms like
PAUSE, CPAN, and search.cpan.org to build indexes saying in which distribution various packages can be
found.
When using tools like Module::Build that can generate the "provides" mapping for your distribution
automatically, make sure you examine what it generates to make sure it makes sense - indexers will
usually trust the "provides" field if it's present, rather than scanning through the distribution files
themselves to figure out packages and versions. This is a good thing, because it means you can use the
"provides" field to tell the indexers precisely what you want indexed about your distribution, rather
than relying on them to essentially guess what you want indexed.
no_index
Example:
no_index:
file:
- My/Module.pm
directory:
- My/Private
package:
- My::Module::Stuff
namespace:
- My::Module::Stuff
(Spec 1.1) [optional] {map} A YAML mapping that describes any files, directories, packages, and
namespaces that are private (i.e. implementation artifacts) that are not of interest to searching and
indexing tools. This is useful when no "provides" field is present.
For example, <http://search.cpan.org/> excludes items listed in "no_index" when searching for POD,
meaning files in these directories will not converted to HTML and made public - which is useful if you
have example or test PODs that you don't want the search engine to go through.
file
(Spec 1.1) [optional] Exclude any listed file(s).
directory
(Spec 1.1) [optional] Exclude anything below the listed directory(ies).
[Note: previous editions of the spec had "dir" instead of "directory", but I think MakeMaker and various
users started using "directory", so in deference we switched to that.]
package
(Spec 1.1) [optional] Exclude the listed package(s).
namespace
(Spec 1.1) [optional] Excludes anything below the listed namespace(s), but not the listed namespace(s)
its self.
keywords
Example:
keywords:
- make
- build
- install
(Spec 1.1) [optional] {list} A sequence of keywords/phrases that describe this distribution.
resources
Example:
resources:
license: http://dev.perl.org/licenses/
homepage: http://sourceforge.net/projects/module-build
bugtracker: http://rt.cpan.org/NoAuth/Bugs.html?Dist=Module-Build
repository: http://sourceforge.net/cvs/?group_id=45731
MailingList: http://lists.sourceforge.net/lists/listinfo/module-build-general
(Spec 1.1) [optional] {map} A mapping of any URL resources related to this distribution. All-lower-case
keys, such as "homepage", "license", and "bugtracker", are reserved by this specification, as they have
"official" meanings defined here in this specification. If you'd like to add your own "special" entries
(like the "MailingList" entry above), use at least one upper-case letter.
The current set of official keys is:
homepage
The official home of this project on the web.
license
An URL for an official statement of this distribution's license.
bugtracker
An URL for a bug tracker (e.g. Bugzilla or RT queue) for this project.
generated_by
Example:
generated_by: Module::Build version 0.20
(Spec 1.0) [required] {string} Indicates the tool that was used to create this META.yml file. It's good
form to include both the name of the tool and its version, but this field is essentially opaque, at least
for the moment. If META.yml was generated by hand, it is suggested that the author be specified here.
[Note: My meta_stats.pl script which I use to gather statistics regarding META.yml usage prefers the form
listed above, i.e. it splits on /\s+version\s+/ taking the first field as the name of the tool that
generated the file and the second field as version of that tool. RWS]
VERSION SPECIFICATIONS
Some fields require a version specification (ex. "requires", "recommends", "build_requires", etc.) to
indicate the particular version(s) of some other module that may be required as a prerequisite. This
section details the version specification formats that are currently supported.
The simplest format for a version specification is just the version number itself, e.g. 2.4. This means
that at least version 2.4 must be present. To indicate that any version of a prerequisite is okay, even
if the prerequisite doesn't define a version at all, use the version 0.
You may also use the operators < (less than), <= (less than or equal), > (greater than), >= (greater than
or equal), == (equal), and != (not equal). For example, the specification < 2.0 means that any version
of the prerequisite less than 2.0 is suitable.
For more complicated situations, version specifications may be AND-ed together using commas. The
specification >= 1.2, != 1.5, < 2.0 indicates a version that must be at least 1.2, less than 2.0, and not
equal to 1.5.
SEE ALSO
CPAN <http://www.cpan.org/>
CPAN.pm
CPANPLUS
Data::Dumper
ExtUtils::MakeMaker
Module::Build
Module::Install
XML <http://www.w3.org/XML/>
YAML <http://www.yaml.org/>
HISTORY
March 14, 2003 (Pi day)
• Created version 1.0 of this document.
May 8, 2003
• Added the "dynamic_config" field, which was missing from the initial version.
November 13, 2003
• Added more YAML rationale articles.
• Fixed existing link to YAML discussion thread to point to new <http://nntp.x.perl.org/group/> site.
• Added and deprecated the "private" field.
• Added "abstract", "configure", "requires_packages", "requires_os", "excludes_os", and "no_index"
fields.
• Bumped version.
November 16, 2003
• Added "generation", "authored_by" fields.
• Add alternative proposal to the "recommends" field.
• Add proposal for a "requires_build_tools" field.
December 9, 2003
• Added link to latest version of this specification on CPAN.
• Added section "VERSION SPECIFICATIONS".
• Chang name from Module::Build::META-spec to CPAN::META::Specification.
• Add proposal for "auto_regenerate" field.
December 15, 2003
• Add "index" field as a compliment to "no_index"
• Add "keywords" field as a means to aid searching distributions.
• Add "TERMINOLOGY" section to explain certain terms that may be ambiguous.
July 26, 2005
• Removed a bunch of items (generation, requires_build_tools, requires_packages, configure,
requires_os, excludes_os, auto_regenerate) that have never actually been supported, but were more
like records of brainstorming.
• Changed "authored_by" to "author", since that's always been what it's actually called in actual
META.yml files.
• Added the "==" operator to the list of supported version-checking operators.
• Noted that the "distribution_type" field is basically meaningless, and shouldn't really be used.
• Clarified "dynamic_config" a bit.
August 23, 2005
• Removed the name "CPAN::META::Specification", since that implies a module that doesn't actually
exist.
June 12, 2007
• Added "configure_requires".
perl v5.40.1 2025-07-03 CPAN::Meta::History::Meta_1_4(3perl)