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

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();

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.

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;

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

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

The options can be ...

The name of the subroutine to create in your namespace.

By default this is 'plugins'

An array ref of namespaces to look in.

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

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.

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

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

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.

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

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

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.

Simon Wistow <simon@thegestalt.org>

Copyright, 2003 Simon Wistow

Distributed under the same terms as Perl itself.

None known.

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