--- /dev/null
+package MooseX::Object::Pluggable;
+
+use Carp;
+use strict;
+use warnings;
+use Moose::Role;
+use Class::Inspector;
+
+
+our $VERSION = '0.0002';
+
+=head1 NAME
+
+ MooseX::Object::Pluggable - Make your classes pluggable
+
+=head1 SYNOPSIS
+
+ package MyApp;
+ use Moose;
+
+ with 'MooseX::Object::Pluggable';
+
+ ...
+
+ package MyApp::Plugin::Pretty;
+ use Moose::Role;
+
+ sub pretty{ print "I am pretty" }
+
+ 1;
+
+ #
+ use MyApp;
+ my $app = MyApp->new;
+ $app->load_plugin('Pretty');
+ $app->pretty;
+
+=head1 DESCRIPTION
+
+This module is meant to be loaded as a role from Moose-based classes
+it will add five methods and five attributes to assist you with the loading
+and handling of plugins and extensions for plugins. I understand that this may
+pollute your namespace, however I took great care in using the least ambiguous
+names possible.
+
+=head1 How plugins Work
+
+Plugins and extensions are just Roles by a fancy name. They are loaded at runtime
+on demand and are instance, not class based. This means that if you have more than
+one instance of a class they can all have different plugins loaded. This is a feature.
+
+Plugin methods are allowed to C<around>, C<before>, C<after>
+their consuming classes, so it is important to watch for load order as plugins can
+and will overload each other. You may also add attributes through has.
+
+Even thouch C<override> will work in basic cases, I STRONGLY discourage it's use
+and a warning will be thrown if you try to use it.
+This is closely linked to the way multiple roles being applies is handles and is not
+likely to change. C<override> bevavior is closely linked to inheritance and thus will
+likely not work as you expect it in multiple inheritance situations. Point being,
+save yourself the headache.
+
+=head1 How plugins are loaded
+
+You don't really need to understand anything except for the first paragraph.
+
+The first time you load a plugin a new anonymous L<Moose::Meta::Class> will be
+created. This class will inherit from your pluggable object and then your object
+will be reblessed to an instance of this anonymous class. This means that
+C<$self-E<gt>blessed> and C<ref $self> will no longer return the name of your object,
+they will instead return the name of the anonymous class created at runtime. Your
+original class name can be located at C<($self-E<gt>meta-E<gt>superclasses)[0]>
+
+Once the anonymous subclass exists all plugin roles will be C<apply>ed to this class
+directly. This "subclass" though is in fact now C<$self> and it C<isa($yourclassname)>.
+ If this is confusing.. it should be, thats why you let me handle it. Just know that it
+has to be done this way in order for plugins to override core functionality.
+
+=head1
+
+For a simple example see the tests for this distribution.
+
+=head1 Attributes
+
+=head2 _plugin_ns
+
+String. The prefix to use for plugin names provided. MyApp::Plugin is sensible.
+
+=head2 _plugin_ext
+
+Boolean. Indicates whether we should attempt to load plugin extensions.
+Defaults to true;
+
+=head2 _plugin_ext_ns
+
+String. The namespace plugin extensions have. Defaults to 'ExtensionFor'.
+
+This means that is _plugin_ns is "MyApp::Plugin" and _plugin_ext_ns is
+"ExtensionFor" loading plugin "Bar" would search for extensions in
+"MyApp::Plugin::Bar::ExtensionFor::*".
+
+=head2 _plugin_loaded
+
+HashRef. Keeps an inventory of what plugins are loaded and what the actual
+module name is to avoid multiple loading.
+
+=head2 __plugin_subclass
+
+Object. This holds the subclass of our pluggable object in the form of an
+anonymous L<Moose::Meta::Class> instance. All roles are actually applied to
+this instance instead of the original class instance in order to not lose
+the original object name as roles are applied. The anonymous class will be
+automatically generated upon first use.
+
+=cut
+
+#--------#---------#---------#---------#---------#---------#---------#---------#
+
+has _plugin_ns => (is => 'rw', required => 1, isa => 'Str',
+ default => 'Plugin');
+
+has _plugin_ext => (is => 'rw', required => 1, isa => 'Bool',
+ default => 1);
+has _plugin_ext_ns => (is => 'rw', required => 1, isa => 'Str',
+ default => 'ExtensionFor');
+has _plugin_loaded => (is => 'rw', required => 1, isa => 'HashRef',
+ default => sub{ {} });
+
+has __plugin_subclass => ( is => 'rw', required => 0, isa => 'Object', );
+
+#--------#---------#---------#---------#---------#---------#---------#---------#
+
+=head1 Public Methods
+
+=head2 load_plugin $plugin
+
+This is the only method you should be using.
+Load the apropriate role for C<$plugin> as well as any
+extensions it provides if extensions are enabled.
+
+=cut
+
+sub load_plugin{
+ my ($self, $plugin) = @_;
+ die("You must provide a plugin name") unless $plugin;
+
+ my $loaded = $self->_plugin_loaded;
+ return 1 if exists $loaded->{$plugin};
+
+ my $role = $self->_role_from_plugin($plugin);
+
+ $loaded->{$plugin} = $role if $self->_load_and_apply_role($role);
+ $self->load_plugin_ext($plugin) if $self->_plugin_ext;
+
+ return exists $loaded->{$plugin};
+}
+
+
+=head2 _load_plugin_ext
+
+Will load any extensions for a particular plugin. This should be called
+automatically by C<load_plugin> so you don't need to worry about it.
+It basically attempts to load any extension that exists for a plugin
+that is already loaded. The only reason for using this is if you want to
+keep _plugin_ext as false and only load extensions manually, which I don't
+recommend.
+
+=cut
+
+sub load_plugin_ext{
+ my ($self, $plugin) = @_;
+ die("You must provide a plugin name") unless $plugin;
+ my $role = $self->_role_from_plugin($plugin);
+
+ # $p for plugin, $r for role
+ while( my($p,$r) = each %{ $self->_plugin_loaded }){
+ my $ext = join "::", $role, $self->_plugin_ext_ns, $p;
+
+ $self->_load_and_apply_role( $ext )
+ if Class::Inspector->installed($ext);
+
+ #go back to prev loaded modules and load extensions for current module?
+ #my $ext2 = join "::", $r, $self->_plugin_ext_ns, $plugin;
+ #$self->_load_and_apply_role( $ext2 )
+ # if Class::Inspector->installed($ext2);
+ }
+}
+
+=head1 Private Methods
+
+There's nothing stopping you from using these, but if you are using them
+you are probably doing something wrong.
+
+=head2 _plugin_subclass
+
+Creates, if needed and returns the anonymous instance of the consuming objects
+subclass to which roles will be applied to.
+
+=cut
+
+sub _plugin_subclass{
+ my $self = shift;
+ my $anon_class = $self->__plugin_subclass;
+
+ #initialize if we havnt been initialized already.
+ unless(ref $anon_class && $self->meta->is_anon_class){
+
+ #create an anon class that inherits from $self that plugins can be
+ #applied to safely and store it within the $self instance.
+ $anon_class = Moose::Meta::Class->
+ create_anon_class(superclasses => [$self->meta->name]);
+ $self->__plugin_subclass( $anon_class );
+
+ #rebless $self as the anon class which now inherits from ourselves
+ #this allows the anon class to override methods in the consuming
+ #class while keeping a stable name and set of superclasses
+ bless $self => $anon_class->name
+ unless $self->meta->name eq $anon_class->name;
+ }
+
+ return $anon_class;
+}
+
+=head2 _role_from_plugin $plugin
+
+Creates a role name from a plugin name. If the plugin name is prepended
+with a C<+> it will be treated as a full name returned as is. Otherwise
+a string consisting of C<$plugin> prepended with the application name
+and C<_plugin_ns> will be returned. Example
+
+ #assuming appname MyApp and C<_plugin_ns> 'Plugin'
+ $self->_role_from_plugin("MyPlugin"); # MyApp::Plugin::MyPlugin
+
+=cut
+
+sub _role_from_plugin{
+ my ($self, $plugin) = @_;
+
+ my $name = $self->meta->is_anon_class ?
+ ($self->meta->superclasses)[0] : $self->blessed;
+
+ $plugin =~ /^\+(.*)/ ? $1 : join '::', $name, $self->_plugin_ns, $plugin;
+}
+
+=head2 _load_and_apply_role $role
+
+Require C<$role> if it is not already loaded and apply it to
+C<_plugin_subclass>. This is the meat of this module.
+
+=cut
+
+sub _load_and_apply_role{
+ my ($self, $role) = @_;
+ die("You must provide a role name") unless $role;
+
+ #Throw exception if plugin is not installed
+ die("$role is not available on this system")
+ unless Class::Inspector->installed($role);
+
+ #don't re-require...
+ unless( Class::Inspector->loaded($role) ){
+ eval "require $role" || die("Failed to load role: $role");
+ }
+
+ carp("Using 'override' is strongly discouraged and may not behave ".
+ "as you expect it to. Please use 'around'")
+ if scalar keys %{ $role->meta->get_override_method_modifiers_map };
+
+ #apply the plugin to the anon subclass
+ die("Failed to apply plugin: $role")
+ unless $role->meta->apply( $self->_plugin_subclass );
+
+ return 1;
+}
+
+
+1;
+
+__END__;
+
+=head1 SEE ALSO
+
+L<Moose>, L<Moose::Role>
+
+=head1 AUTHOR
+
+Guillermo Roditi, <groditi@cpan.org>
+
+=head1 BUGS
+
+Holler?
+
+Please report any bugs or feature requests to
+C<bug-moosex-object-pluggable at rt.cpan.org>, or through the web interface at
+L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=MooseX-Object-Pluggable>.
+I will be notified, and then you'll automatically be notified of progress on
+your bug as I make changes.
+
+=head1 SUPPORT
+
+You can find documentation for this module with the perldoc command.
+
+ perldoc MooseX-Object-Pluggable
+
+You can also look for information at:
+
+=over 4
+
+=item * AnnoCPAN: Annotated CPAN documentation
+
+L<http://annocpan.org/dist/MooseX-Object-Pluggable>
+
+=item * CPAN Ratings
+
+L<http://cpanratings.perl.org/d/MooseX-Object-Pluggable>
+
+=item * RT: CPAN's request tracker
+
+L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=MooseX-Object-Pluggable>
+
+=item * Search CPAN
+
+L<http://search.cpan.org/dist/MooseX-Object-Pluggable>
+
+=back
+
+=head1 ACKNOWLEDGEMENTS
+
+=over 4
+
+=item #Moose - Huge number of questions
+
+=item Matt S Trout <mst@shadowcatsystems.co.uk> - ideas / planning.
+
+=item Stevan Little - EVERYTHING. Without him this would have never happened.
+
+=back
+
+=head1 COPYRIGHT
+
+Copyright 2007 Guillermo Roditi. All Rights Reserved. This is
+free software; you may redistribute it and/or modify it under the same
+terms as Perl itself.
+
+=cut
projects / gitmo/MooseX-Object-Pluggable.git / commitdiff