1 package MooseX::Object::Pluggable;
6 use Module::Pluggable::Object;
8 our $VERSION = '0.0006';
12 MooseX::Object::Pluggable - Make your classes pluggable
19 with 'MooseX::Object::Pluggable';
23 package MyApp::Plugin::Pretty;
26 sub pretty{ print "I am pretty" }
33 $app->load_plugin('Pretty');
38 This module is meant to be loaded as a role from Moose-based classes
39 it will add five methods and four attributes to assist you with the loading
40 and handling of plugins and extensions for plugins. I understand that this may
41 pollute your namespace, however I took great care in using the least ambiguous
44 =head1 How plugins Work
46 Plugins and extensions are just Roles by a fancy name. They are loaded at runtime
47 on demand and are instance, not class based. This means that if you have more than
48 one instance of a class they can all have different plugins loaded. This is a feature.
50 Plugin methods are allowed to C<around>, C<before>, C<after>
51 their consuming classes, so it is important to watch for load order as plugins can
52 and will overload each other. You may also add attributes through has.
54 Please note that when you load at runtime you lose the ability to wrap C<BUILD>
55 and roles using C<has> will not go through comile time checks like C<required>
58 Even though C<override> will work , I STRONGLY discourage it's use
59 and a warning will be thrown if you try to use it.
60 This is closely linked to the way multiple roles being applies is handles and is not
61 likely to change. C<override> bevavior is closely linked to inheritance and thus will
62 likely not work as you expect it in multiple inheritance situations. Point being,
63 save yourself the headache.
65 =head1 How plugins are loaded
67 When roles are applied at runtime an anonymous class will wrap your class and
68 C<$self-E<gt>blessed> and C<ref $self> will no longer return the name of your object,
69 they will instead return the name of the anonymous class created at runtime.
70 See C<_original_class_name>.
72 =head1 Notice regarding extensions.
74 Because I have been able to identify a real-world use case for the extension mechanism
75 I have decided to deprecate it and remove it in the next major release.
79 For a simple example see the tests included in this distribution.
85 String. The prefix to use for plugin names provided. MyApp::Plugin is sensible.
89 Boolean. Indicates whether we should attempt to load plugin extensions.
94 B<THIS FUNCTIONALITY HAS BEEN DEPRECATED AND WILL GO AWAY.> If you use
95 this, please email me, but I am fairly sure that nobody uses this at
96 all and it's just adding bloat and making things kind of ugly.
98 String. The namespace plugin extensions have. Defaults to 'ExtensionFor'.
100 This means that is _plugin_ns is "MyApp::Plugin" and _plugin_ext_ns is
101 "ExtensionFor" loading plugin "Bar" would search for extensions in
102 "MyApp::Plugin::Bar::ExtensionFor::*".
104 =head2 _plugin_app_ns
106 ArrayRef, Accessor automatically dereferences into array on a read call.
107 By default will be filled with the class name and it's prescedents, it is used
108 to determine which directories to look for plugins as well as which plugins
109 take presedence upon namespace collitions. This allows you to subclass a pluggable
110 class and still use it's plugins while using yours first if they are available.
114 =head2 _plugin_locator
116 An automatically built instance of L<Module::Pluggable::Object> used to locate
121 #--------#---------#---------#---------#---------#---------#---------#---------#
123 has _plugin_ns => (is => 'rw', required => 1, isa => 'Str',
124 default => 'Plugin');
125 has _plugin_ext => (is => 'rw', required => 1, isa => 'Bool',
127 has _plugin_ext_ns => (is => 'rw', required => 1, isa => 'Str',
128 default => 'ExtensionFor');
129 has _plugin_loaded => (is => 'rw', required => 1, isa => 'HashRef',
130 default => sub{ {} });
131 has _plugin_app_ns => (is => 'rw', required => 1, isa => 'ArrayRef', lazy => 1,
133 default => sub{ shift->_build_plugin_app_ns },
134 trigger => sub{ $_[0]->_clear_plugin_locator
135 if $_[0]->_has_plugin_locator; },
137 has _plugin_locator => (is => 'rw', required => 1, lazy => 1,
138 isa => 'Module::Pluggable::Object',
139 clearer => '_clear_plugin_locator',
140 predicate => '_has_plugin_locator',
141 default => sub{ shift->_build_plugin_locator });
143 #--------#---------#---------#---------#---------#---------#---------#---------#
145 =head1 Public Methods
147 =head2 load_plugin $plugin
149 Load the apropriate role for C<$plugin> as well as any extensions it provides
150 if extensions are enabled.
155 my ($self, $plugin) = @_;
156 die("You must provide a plugin name") unless $plugin;
158 my $loaded = $self->_plugin_loaded;
159 return 1 if exists $loaded->{$plugin};
161 my $role = $self->_role_from_plugin($plugin);
163 $loaded->{$plugin} = $role if $self->_load_and_apply_role($role);
164 $self->load_plugin_ext($plugin) if $self->_plugin_ext;
166 return exists $loaded->{$plugin};
169 =head2 load_plugins @plugins
171 Load all C<@plugins>.
178 $self->load_plugin($_) for @_;
182 =head2 load_plugin_ext
184 B<THIS FUNCTIONALITY HAS BEEN DEPRECATED AND WILL GO AWAY.> If you use
185 this, please email me, but I am fairly sure that nobody uses this at
186 all and it's just adding bloat and making things kind of ugly.
188 Will load any extensions for a particular plugin. This should be called
189 automatically by C<load_plugin> so you don't need to worry about it.
190 It basically attempts to load any extension that exists for a plugin
191 that is already loaded. The only reason for using this is if you want to
192 keep _plugin_ext as false and only load extensions manually, which I don't
198 my ($self, $plugin) = @_;
199 die("You must provide a plugin name") unless $plugin;
200 my $role = $self->_plugin_loaded->{$plugin};
202 # $p for plugin, $r for role
203 while( my($p,$r) = each %{ $self->_plugin_loaded }){
205 my $ext = join "::", $role, $self->_plugin_ext_ns, $p;
206 if( $plugin =~ /^\+(.*)/ ){
207 eval{ $self->_load_and_apply_role( $ext ) };
209 $self->_load_and_apply_role( $ext ) if
210 grep{ /^${ext}$/ } $self->_plugin_locator->plugins;
213 #go back to prev loaded modules and load extensions for current module?
214 #my $ext2 = join "::", $r, $self->_plugin_ext_ns, $plugin;
215 #$self->_load_and_apply_role( $ext2 )
216 # if Class::Inspector->installed($ext2);
220 =head2 _original_class_name
222 Because of the way roles apply C<$self-E<gt>blessed> and C<ref $self> will
223 no longer return what you expect. Instead use this class to get your original
228 sub _original_class_name{
230 return (grep {$_ !~ /^Moose::/} $self->meta->class_precedence_list)[0];
234 =head1 Private Methods
236 There's nothing stopping you from using these, but if you are using them
237 for anything thats not really complicated you are probably doing
238 something wrong. Some of these may be inlined in the future if performance
239 becomes an issue (which I doubt).
241 =head2 _role_from_plugin $plugin
243 Creates a role name from a plugin name. If the plugin name is prepended
244 with a C<+> it will be treated as a full name returned as is. Otherwise
245 a string consisting of C<$plugin> prepended with the C<_plugin_ns>
246 and the first valid value from C<_plugin_app_ns> will be returned. Example
248 #assuming appname MyApp and C<_plugin_ns> 'Plugin'
249 $self->_role_from_plugin("MyPlugin"); # MyApp::Plugin::MyPlugin
253 sub _role_from_plugin{
254 my ($self, $plugin) = @_;
256 return $1 if( $plugin =~ /^\+(.*)/ );
258 my $o = join '::', $self->_plugin_ns, $plugin;
259 #Father, please forgive me for I have sinned.
260 my @roles = grep{ /${o}$/ } $self->_plugin_locator->plugins;
262 die("Unable to locate plugin") unless @roles;
263 return $roles[0] if @roles == 1;
266 my %presedence_list = map{ $i++; "${_}::${o}", $i } $self->_plugin_app_ns;
268 @roles = sort{ $presedence_list{$a} <=> $presedence_list{$b}} @roles;
273 =head2 _load_and_apply_role $role
275 Require C<$role> if it is not already loaded and apply it. This is
276 the meat of this module.
280 sub _load_and_apply_role{
281 my ($self, $role) = @_;
282 die("You must provide a role name") unless $role;
285 unless( Class::MOP::is_class_loaded($role) ){
286 eval Class::MOP::load_class($role) || die("Failed to load role: $role");
289 carp("Using 'override' is strongly discouraged and may not behave ".
290 "as you expect it to. Please use 'around'")
291 if scalar keys %{ $role->meta->get_override_method_modifiers_map };
292 die("Failed to apply plugin: $role") unless $role->meta->apply( $self );
297 =head2 _build_plugin_app_ns
299 Automatically builds the _plugin_app_ns attribute with the classes in the
300 class presedence list that are not part of Moose.
304 sub _build_plugin_app_ns{
306 my @names = (grep {$_ !~ /^Moose::/} $self->meta->class_precedence_list);
310 =head2 _build_plugin_locator
312 Automatically creates a L<Module::Pluggable::Object> instance with the correct
317 sub _build_plugin_locator{
320 my $locator = Module::Pluggable::Object->new
322 [ map { join '::', ($_, $self->_plugin_ns) } $self->_plugin_app_ns ]
329 Keep tests happy. See L<Moose>
339 L<Moose>, L<Moose::Role>, L<Class::Inspector>
343 Guillermo Roditi, <groditi@cpan.org>
349 Please report any bugs or feature requests to
350 C<bug-moosex-object-pluggable at rt.cpan.org>, or through the web interface at
351 L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=MooseX-Object-Pluggable>.
352 I will be notified, and then you'll automatically be notified of progress on
353 your bug as I make changes.
357 You can find documentation for this module with the perldoc command.
359 perldoc MooseX-Object-Pluggable
361 You can also look for information at:
365 =item * AnnoCPAN: Annotated CPAN documentation
367 L<http://annocpan.org/dist/MooseX-Object-Pluggable>
371 L<http://cpanratings.perl.org/d/MooseX-Object-Pluggable>
373 =item * RT: CPAN's request tracker
375 L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=MooseX-Object-Pluggable>
379 L<http://search.cpan.org/dist/MooseX-Object-Pluggable>
383 =head1 ACKNOWLEDGEMENTS
387 =item #Moose - Huge number of questions
389 =item Matt S Trout <mst@shadowcatsystems.co.uk> - ideas / planning.
391 =item Stevan Little - EVERYTHING. Without him this would have never happened.
397 Copyright 2007 Guillermo Roditi. All Rights Reserved. This is
398 free software; you may redistribute it and/or modify it under the same
399 terms as Perl itself.