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.

        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

    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 ...

    file_regex => qr/\.plugin$/

METHODs¶

    $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