


Module::PluggablePerl Programmers Reference Module::Pluggable(3p)


NAME
       Module::Pluggable - automatically give your module the
       ability to have plugins

SYNOPSIS
       Simple use Module::Pluggable -

           package MyClass;
           use Module::Pluggable;

       and then later ...

           use MyClass;
           my $mc = MyClass->new();
           # returns the names of all plugins installed under MyClass::Plugin::*
           my @plugins = $mc->plugins();

EXAMPLE
       Why would you want to do this? Say you have something that
       wants to pass an object to a number of different plugins
       in turn. For example you may want to extract meta-data
       from every email you get sent and do something with it.
       Plugins make sense here because then you can keep adding
       new meta data parsers and all the logic and docs for each
       one will be self contained and new handlers are easy to
       add without changing the core code. For that, you might do
       something like ...

           package Email::Examiner;

           use strict;
           use Email::Simple;
           use Module::Pluggable require => 1;

           sub handle_email {
               my $self  = shift;
               my $email = shift;

               foreach my $plugin ($self->plugins) {
                   $plugin->examine($email);
               }

               return 1;
           }

       .. and all the plugins will get a chance in turn to look
       at it.

       This can be trivally extended so that plugins could save
       the email somewhere and then no other plugin should try
       and do that.  Simply have it so that the "examine" method
       returns 1 if it has saved the email somewhere. You might
       also wnat to be paranoid and check to see if the plugin
       has an "examine" method.



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Module::PluggablePerl Programmers Reference Module::Pluggable(3p)


               foreach my $plugin ($self->plugins) {
                   next unless $plugin->can('examine');
                   last if     $plugin->examine($email);
               }

       And so on. The sky's the limit.

DESCRIPTION
       Provides a simple but, hopefully, extensible way of having
       'plugins' for your module. Obviously this isn't going to
       be the be all and end all of solutions but it works for
       me.

       Essentially all it does is export a method into your
       namespace that looks through a search path for .pm files
       and turn those into class names.

       Optionally it instantiates those classes for you.

ADVANCED USAGE
       Alternatively, if you don't want to use 'plugins' as the
       method ...

           package MyClass;
           use Module::Pluggable sub_name => 'foo';

       and then later ...

           my @plugins = $mc->foo();

       Or if you want to look in another namespace

           package MyClass;
           use Module::Pluggable search_path => ['Acme::MyClass::Plugin', 'MyClass::Extend'];

       or directory

           use Module::Pluggable search_dirs => ['mylibs/Foo'];

       Or if you want to instantiate each plugin rather than just
       return the name

           package MyClass;
           use Module::Pluggable instantiate => 'new';

       and then

           # whatever is passed to 'plugins' will be passed
           # to 'new' for each plugin
           my @plugins = $mc->plugins(@options);

       alternatively you can just require the module without
       instantiating it




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Module::PluggablePerl Programmers Reference Module::Pluggable(3p)


           package MyClass;
           use Module::Pluggable require => 1;

       since requiring automatically searches inner packages,
       which may not be desirable, you can turn this off

           package MyClass;
           use Module::Pluggable require => 1, inner => 0;

       You can limit the plugins loaded using the except option,
       either as a string, array ref or regex

           package MyClass;
           use Module::Pluggable except => 'MyClass::Plugin::Foo';

       or

           package MyClass;
           use Module::Pluggable except => ['MyClass::Plugin::Foo', 'MyClass::Plugin::Bar'];

       or

           package MyClass;
           use Module::Pluggable except => qr/^MyClass::Plugin::(Foo|Bar)$/;

       and similarly for only which will only load plugins which
       match.

       Remember you can use the module more than once

           package MyClass;
           use Module::Pluggable search_path => 'MyClass::Filters' sub_name => 'filters';
           use Module::Pluggable search_path => 'MyClass::Plugins' sub_name => 'plugins';

       and then later ...

           my @filters = $self->filters;
           my @plugins = $self->plugins;

INNER PACKAGES
       If you have, for example, a file
       lib/Something/Plugin/Foo.pm that contains package
       definitions for both "Something::Plugin::Foo" and
       "Something::Plugin::Bar" then as long as you either have
       either the require or instantiate option set then we'll
       also find "Something::Plugin::Bar". Nifty!

OPTIONS
       You can pass a hash of options when importing this module.

       The options can be ...

   sub_name
       The name of the subroutine to create in your namespace.



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Module::PluggablePerl Programmers Reference Module::Pluggable(3p)


       By default this is 'plugins'

   search_path
       An array ref of namespaces to look in.

   search_dirs
       An array ref of directorys to look in before @INC.

   instantiate
       Call this method on the class. In general this will
       probably be 'new' but it can be whatever you want.
       Whatever arguments are passed to 'plugins' will be passed
       to the method.

       The default is 'undef' i.e just return the class name.

   require
       Just require the class, don't instantiate (overrides
       'instantiate');

   inner
       If set to 0 will not search inner packages.  If set to 1
       will override "require".

   only
       Takes a string, array ref or regex describing the names of
       the only plugins to return. Whilst this may seem perverse
       ... well, it is. But it also makes sense. Trust me.

   except
       Similar to "only" it takes a description of plugins to
       exclude from returning. This is slightly less perverse.

   package
       This is for use by extension modules which build on
       "Module::Pluggable": passing a "package" option allows you
       to place the plugin method in a different package other
       than your own.

   file_regex
       By default "Module::Pluggable" only looks for .pm files.

       By supplying a new "file_regex" then you can change this
       behaviour e.g

           file_regex => qr/\.plugin$/

   include_editor_junk
       By default "Module::Pluggable" ignores files that look
       like they were left behind by editors. Currently this
       means files ending in ~ (~), the extensions .swp or .swo,
       or files beginning with .#.

       Setting "include_editor_junk" changes "Module::Pluggable"



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Module::PluggablePerl Programmers Reference Module::Pluggable(3p)


       so it does not ignore any files it finds.

METHODs
   search_path
       The method "search_path" is exported into you namespace as
       well.  You can call that at any time to change or replace
       the search_path.

           $self->search_path( add => "New::Path" ); # add
           $self->search_path( new => "New::Path" ); # replace

FUTURE PLANS
       This does everything I need and I can't really think of
       any other features I want to add. Famous last words of
       course

       Recently tried fixed to find inner packages and to make it
       'just work' with PAR but there are still some issues.

       However suggestions (and patches) are welcome.

AUTHOR
       Simon Wistow <simon@thegestalt.org>

COPYING
       Copyright, 2006 Simon Wistow

       Distributed under the same terms as Perl itself.

BUGS
       None known.

SEE ALSO
       File::Spec, File::Find, File::Basename,
       Class::Factory::Util, Module::Pluggable::Ordered






















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