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1 | package MooseX::Object::Pluggable; |
2 | |
3 | use Carp; |
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4 | use Moose::Role; |
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5 | use Class::MOP; |
6 | use Module::Pluggable::Object; |
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7 | |
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8 | our $VERSION = '0.0007'; |
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9 | |
10 | =head1 NAME |
11 | |
12 | MooseX::Object::Pluggable - Make your classes pluggable |
13 | |
14 | =head1 SYNOPSIS |
15 | |
16 | package MyApp; |
17 | use Moose; |
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18 | |
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19 | with 'MooseX::Object::Pluggable'; |
20 | |
21 | ... |
22 | |
23 | package MyApp::Plugin::Pretty; |
24 | use Moose::Role; |
25 | |
26 | sub pretty{ print "I am pretty" } |
27 | |
28 | 1; |
29 | |
30 | # |
31 | use MyApp; |
32 | my $app = MyApp->new; |
33 | $app->load_plugin('Pretty'); |
34 | $app->pretty; |
35 | |
36 | =head1 DESCRIPTION |
37 | |
38 | This module is meant to be loaded as a role from Moose-based classes |
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39 | it will add five methods and four attributes to assist you with the loading |
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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 |
42 | names possible. |
43 | |
44 | =head1 How plugins Work |
45 | |
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. |
49 | |
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. |
53 | |
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54 | Please note that when you load at runtime you lose the ability to wrap C<BUILD> |
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55 | and roles using C<has> will not go through compile time checks like C<required> |
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56 | and <default>. |
57 | |
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58 | Even though C<override> will work , I STRONGLY discourage it's use |
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59 | and a warning will be thrown if you try to use it. |
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60 | This is closely linked to the way multiple roles being applied is handled and is not |
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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. |
64 | |
65 | =head1 How plugins are loaded |
66 | |
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67 | When roles are applied at runtime an anonymous class will wrap your class and |
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68 | C<$self-E<gt>blessed> and C<ref $self> will no longer return the name of your object, |
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69 | they will instead return the name of the anonymous class created at runtime. |
70 | See C<_original_class_name>. |
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71 | |
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72 | =head1 Notice regarding extensions. |
73 | |
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. |
76 | |
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77 | =head1 Usage |
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78 | |
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79 | For a simple example see the tests included in this distribution. |
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80 | |
81 | =head1 Attributes |
82 | |
83 | =head2 _plugin_ns |
84 | |
85 | String. The prefix to use for plugin names provided. MyApp::Plugin is sensible. |
86 | |
87 | =head2 _plugin_ext |
88 | |
89 | Boolean. Indicates whether we should attempt to load plugin extensions. |
90 | Defaults to true; |
91 | |
92 | =head2 _plugin_ext_ns |
93 | |
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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. |
97 | |
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98 | String. The namespace plugin extensions have. Defaults to 'ExtensionFor'. |
99 | |
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 |
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102 | "MyApp::Plugin::Bar::ExtensionFor::*". |
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103 | |
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104 | =head2 _plugin_app_ns |
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105 | |
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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. |
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111 | |
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112 | =cut |
113 | |
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114 | =head2 _plugin_locator |
115 | |
116 | An automatically built instance of L<Module::Pluggable::Object> used to locate |
117 | available plugins. |
118 | |
119 | =cut |
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120 | |
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121 | #--------#---------#---------#---------#---------#---------#---------#---------# |
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122 | |
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123 | has _plugin_ns => (is => 'rw', required => 1, isa => 'Str', |
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124 | default => 'Plugin'); |
125 | has _plugin_ext => (is => 'rw', required => 1, isa => 'Bool', |
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126 | default => 1); |
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, |
132 | auto_deref => 1, |
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133 | default => sub{ shift->_build_plugin_app_ns }, |
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134 | trigger => sub{ $_[0]->_clear_plugin_locator |
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135 | if $_[0]->_has_plugin_locator; }, |
136 | ); |
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137 | has _plugin_locator => (is => 'rw', required => 1, lazy => 1, |
138 | isa => 'Module::Pluggable::Object', |
139 | clearer => '_clear_plugin_locator', |
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140 | predicate => '_has_plugin_locator', |
141 | default => sub{ shift->_build_plugin_locator }); |
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142 | |
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143 | #--------#---------#---------#---------#---------#---------#---------#---------# |
144 | |
145 | =head1 Public Methods |
146 | |
147 | =head2 load_plugin $plugin |
148 | |
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149 | Load the apropriate role for C<$plugin> as well as any extensions it provides |
150 | if extensions are enabled. |
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151 | |
152 | =cut |
153 | |
154 | sub load_plugin{ |
155 | my ($self, $plugin) = @_; |
156 | die("You must provide a plugin name") unless $plugin; |
157 | |
158 | my $loaded = $self->_plugin_loaded; |
159 | return 1 if exists $loaded->{$plugin}; |
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160 | |
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161 | my $role = $self->_role_from_plugin($plugin); |
162 | |
163 | $loaded->{$plugin} = $role if $self->_load_and_apply_role($role); |
164 | $self->load_plugin_ext($plugin) if $self->_plugin_ext; |
165 | |
166 | return exists $loaded->{$plugin}; |
167 | } |
168 | |
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169 | =head2 load_plugins @plugins |
170 | |
171 | Load all C<@plugins>. |
172 | |
173 | =cut |
174 | |
175 | |
176 | sub load_plugins { |
177 | my $self = shift; |
178 | $self->load_plugin($_) for @_; |
179 | } |
180 | |
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181 | |
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182 | =head2 load_plugin_ext |
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183 | |
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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. |
187 | |
188 | Will load any extensions for a particular plugin. This should be called |
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189 | automatically by C<load_plugin> so you don't need to worry about it. |
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190 | It basically attempts to load any extension that exists for a plugin |
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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 |
193 | recommend. |
194 | |
195 | =cut |
196 | |
197 | sub load_plugin_ext{ |
198 | my ($self, $plugin) = @_; |
199 | die("You must provide a plugin name") unless $plugin; |
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200 | my $role = $self->_plugin_loaded->{$plugin}; |
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201 | |
202 | # $p for plugin, $r for role |
203 | while( my($p,$r) = each %{ $self->_plugin_loaded }){ |
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204 | |
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205 | my $ext = join "::", $role, $self->_plugin_ext_ns, $p; |
206 | if( $plugin =~ /^\+(.*)/ ){ |
207 | eval{ $self->_load_and_apply_role( $ext ) }; |
208 | } else{ |
209 | $self->_load_and_apply_role( $ext ) if |
210 | grep{ /^${ext}$/ } $self->_plugin_locator->plugins; |
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211 | } |
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212 | |
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); |
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217 | } |
218 | } |
219 | |
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220 | =head2 _original_class_name |
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221 | |
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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 |
224 | class name. |
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225 | |
226 | =cut |
227 | |
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228 | sub _original_class_name{ |
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229 | my $self = shift; |
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230 | return (grep {$_ !~ /^Moose::/} $self->meta->class_precedence_list)[0]; |
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231 | } |
232 | |
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233 | |
234 | =head1 Private Methods |
235 | |
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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 |
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238 | something wrong. Some of these may be inlined in the future if performance |
239 | becomes an issue (which I doubt). |
240 | |
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241 | =head2 _role_from_plugin $plugin |
242 | |
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243 | Creates a role name from a plugin name. If the plugin name is prepended |
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244 | with a C<+> it will be treated as a full name returned as is. Otherwise |
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245 | a string consisting of C<$plugin> prepended with the C<_plugin_ns> |
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246 | and the first valid value from C<_plugin_app_ns> will be returned. Example |
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247 | |
248 | #assuming appname MyApp and C<_plugin_ns> 'Plugin' |
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249 | $self->_role_from_plugin("MyPlugin"); # MyApp::Plugin::MyPlugin |
250 | |
251 | =cut |
252 | |
253 | sub _role_from_plugin{ |
254 | my ($self, $plugin) = @_; |
255 | |
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256 | return $1 if( $plugin =~ /^\+(.*)/ ); |
257 | |
258 | my $o = join '::', $self->_plugin_ns, $plugin; |
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259 | #Father, please forgive me for I have sinned. |
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260 | my @roles = grep{ /${o}$/ } $self->_plugin_locator->plugins; |
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261 | |
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262 | croak("Unable to locate plugin '$plugin'") unless @roles; |
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263 | return $roles[0] if @roles == 1; |
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264 | |
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265 | my $i = 0; |
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266 | my %presedence_list = map{ $i++; "${_}::${o}", $i } $self->_plugin_app_ns; |
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267 | |
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268 | @roles = sort{ $presedence_list{$a} <=> $presedence_list{$b}} @roles; |
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269 | |
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270 | return shift @roles; |
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271 | } |
272 | |
273 | =head2 _load_and_apply_role $role |
274 | |
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275 | Require C<$role> if it is not already loaded and apply it. This is |
276 | the meat of this module. |
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277 | |
278 | =cut |
279 | |
280 | sub _load_and_apply_role{ |
281 | my ($self, $role) = @_; |
282 | die("You must provide a role name") unless $role; |
283 | |
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284 | eval { Class::MOP::load_class($role) }; |
285 | confess("Failed to load role: ${role} $@") if $@; |
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286 | |
287 | carp("Using 'override' is strongly discouraged and may not behave ". |
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288 | "as you expect it to. Please use 'around'") |
289 | if scalar keys %{ $role->meta->get_override_method_modifiers_map }; |
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290 | |
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291 | $role->meta->apply( $self ); |
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292 | return 1; |
293 | } |
294 | |
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295 | =head2 _build_plugin_app_ns |
296 | |
297 | Automatically builds the _plugin_app_ns attribute with the classes in the |
298 | class presedence list that are not part of Moose. |
299 | |
300 | =cut |
301 | |
302 | sub _build_plugin_app_ns{ |
303 | my $self = shift; |
304 | my @names = (grep {$_ !~ /^Moose::/} $self->meta->class_precedence_list); |
305 | return \@names; |
306 | } |
307 | |
308 | =head2 _build_plugin_locator |
309 | |
310 | Automatically creates a L<Module::Pluggable::Object> instance with the correct |
311 | search_path. |
312 | |
313 | =cut |
314 | |
315 | sub _build_plugin_locator{ |
316 | my $self = shift; |
317 | |
318 | my $locator = Module::Pluggable::Object->new |
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319 | ( search_path => |
320 | [ map { join '::', ($_, $self->_plugin_ns) } $self->_plugin_app_ns ] |
321 | ); |
322 | return $locator; |
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323 | } |
324 | |
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325 | =head2 meta |
326 | |
327 | Keep tests happy. See L<Moose> |
328 | |
329 | =cut |
330 | |
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331 | 1; |
332 | |
333 | __END__; |
334 | |
335 | =head1 SEE ALSO |
336 | |
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337 | L<Moose>, L<Moose::Role>, L<Class::Inspector> |
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338 | |
339 | =head1 AUTHOR |
340 | |
341 | Guillermo Roditi, <groditi@cpan.org> |
342 | |
343 | =head1 BUGS |
344 | |
345 | Holler? |
346 | |
347 | Please report any bugs or feature requests to |
348 | C<bug-moosex-object-pluggable at rt.cpan.org>, or through the web interface at |
349 | L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=MooseX-Object-Pluggable>. |
350 | I will be notified, and then you'll automatically be notified of progress on |
351 | your bug as I make changes. |
352 | |
353 | =head1 SUPPORT |
354 | |
355 | You can find documentation for this module with the perldoc command. |
356 | |
357 | perldoc MooseX-Object-Pluggable |
358 | |
359 | You can also look for information at: |
360 | |
361 | =over 4 |
362 | |
363 | =item * AnnoCPAN: Annotated CPAN documentation |
364 | |
365 | L<http://annocpan.org/dist/MooseX-Object-Pluggable> |
366 | |
367 | =item * CPAN Ratings |
368 | |
369 | L<http://cpanratings.perl.org/d/MooseX-Object-Pluggable> |
370 | |
371 | =item * RT: CPAN's request tracker |
372 | |
373 | L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=MooseX-Object-Pluggable> |
374 | |
375 | =item * Search CPAN |
376 | |
377 | L<http://search.cpan.org/dist/MooseX-Object-Pluggable> |
378 | |
379 | =back |
380 | |
381 | =head1 ACKNOWLEDGEMENTS |
382 | |
383 | =over 4 |
384 | |
385 | =item #Moose - Huge number of questions |
386 | |
387 | =item Matt S Trout <mst@shadowcatsystems.co.uk> - ideas / planning. |
388 | |
389 | =item Stevan Little - EVERYTHING. Without him this would have never happened. |
390 | |
391 | =back |
392 | |
393 | =head1 COPYRIGHT |
394 | |
395 | Copyright 2007 Guillermo Roditi. All Rights Reserved. This is |
396 | free software; you may redistribute it and/or modify it under the same |
397 | terms as Perl itself. |
398 | |
399 | =cut |