NAME

       Mason::Manual::UpgradingFromMason1 - Summary of differences between Mason 1 and Mason 2

DESCRIPTION

       Mason 2.x comes ten years after Mason 1.0 (known as HTML::Mason) and twelve years after the original
       Mason release.  It has been rearchitected and reimplemented from the ground up.

       That said, the philosophy and core syntax are similar enough that it should still be recognizable and
       "feel like Mason" to existing users.

       This manual attempts to summarize the differences between Mason 1 and 2, to help existing users decide if
       they are interested and, if so, migrate their projects.

       There is currently no automated way to convert a Mason 1 to a Mason 2 site, but there hopefully will be
       someday. (Contributions welcome. :))

ARCHITECTURE

       •   In Mason 1, each component was an instance of a common Component class. In Mason 2, each component is
           its own Moose class, with a class name generated from the component path.

       •   The main component body - the content and the inline Perl sections - are placed into a "main" method.

       •   Calling  a  component  (via  "<& &>" or "$m->comp" ) entails creating a new instance of the component
           class, and calling its "main" method. Component call parameters are passed  to  the  constructor  and
           placed in attributes.

MAJOR FEATURES

       •   Plugins  now  utilize  Moose  roles  and  are  much  more powerful and flexible than in Mason 1. Some
           features that were  (or  would  have  been)  in  the  core  of  Mason  1  are  now  in  plugins.  See
           Mason::Manual::Plugins.

       •   Web  integration in Mason 1 was centered around mod_perl and was part of the core. In Mason 2 all web
           integration has been split out into a companion web framework, Poet,  which  in  turn  uses  PSGI  to
           integrate  with  any  server  backend.  You can also use Mason as the templating layer in popular web
           frameworks such as Catalyst and Dancer.  There is no longer anything web-specific in the Mason core.

       •   Subcomponents have been eliminated, replaced with class methods.

       •   Error processing/formatting has been eliminated. Mason now simply throws fatal errors to the  caller.
           In a Plack environment, Plack::Middleware::StackTrace will catch the error and format it nicely.

       •   Resolvers  and  Anonymous  components  have been eliminated. Components need to be in files.  If your
           components live in another data source, you could use FUSE <http://fuse.sourceforge.net/> or a custom
           plugin to keep a file hierarchy up to date with the data source.

       •   Caching support has been simplified. "$m->cache" simply returns a  CHI  object  with  an  appropriate
           namespace for the component.

SYNTAX

       •   "<%once>" has been replaced with "<%class>".

       •   "<%cleanup>"  has  been eliminated; it was not very useful anyway, since it was not guaranteed to run
           after an exception. You can use add_cleanup to add cleanup code for the end of the request, which  is
           good enough in most cases, or you can add a "DEMOLISH" method to the component.

       •   Single  blank  lines  between  blocks  are  now  removed, so you can space blocks out for readability
           without generating a ton of newlines.

       •   Whitespace is required after a %-line and around the expression in a  "<%  %>"  tag.   This  improves
           readability and leaves open the possibility of additional syntax.

       •   "<%args>" and "<%shared>" are gone. Use Moose attributes instead.

       •   The  "<%ARGS>"  hash is gone, you can instead use "$.args" or "$self->args" to get all the parameters
           passed to a component.

       •   "<%method>" and "<%def>" have been replaced with just "<%method>", which creates a true class  method
           rather than a subcomponent.

       •   The  "<%filter>" tag is now used to define filters, instead of automatically applying a filter to the
           current component.

       •   "Components with content" syntax has been eliminated; use the CompCall filter instead.

       •   "Escape flags" in substitution tags now utilize filters.

MISC PARAMETER CHANGES

   Interp parameters
       •   "buffer_preallocate_size", "code_cache_max_size" and "use_object_files" have been deemed  unnecessary
           and eliminated.

       •   "escape_flags" has been eliminated; define filters instead.

       •   "data_dir" now defaults to a directory created with tempdir.

       •   "preloads" has been eliminated; this code does roughly the same:

               $interp->load($_) for (grep { /some_condition/ } $interp->all_paths);

   Request parameters
       •   "autoflush"  and  "max_recurse"  have  been  eliminated  because  they are too difficult to implement
           efficiently.

   Compiler parameters
       •   "preprocess", "postprocess_perl", and "postprocess_text" have been eliminated; similar effects can be
           achieved with plugins targeting Mason::Compilation.

       •   "default_escape_flags" has been eliminated, but see Mason::Plugin::DefaultFilter  for  a  third-party
           substitute.

MISC METHOD CHANGES

   Interp methods
       •   "exec" has been renamed to run.

   Request methods
       •   "cache_self" has been eliminated; use the Cache filter instead.

       •   "callers",  "caller"  and  "caller_args"  have  been  eliminated; now that component calls are simply
           method calls underneath, they are too difficult to implement efficiently.

       •   "call_next" has been replaced with Moose's "inner".

       •   "call_self" has been eliminated; use filters instead.

       •   "current_comp" has been eliminated. Within a component, use $self; outside a component you  can  call
           current_comp_class, which will at least get you the class.

       •   "dhandler_arg" has been renamed to path_info.

       •   "exec" has been renamed to run.

       •   "fetch_comp" has been renamed to load.

       •   "subexec" has been replaced with visit and go.

SEE ALSO

       Mason

AUTHOR

       Jonathan Swartz <swartz@pobox.com>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2012 by Jonathan Swartz.

       This  is  free  software;  you  can  redistribute  it and/or modify it under the same terms as the Perl 5
       programming language system itself.

perl v5.34.0                                       2022-05-27             Mason::Manual::...adingFromMason1(3pm)