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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 = '0.0008'; |
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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 Usage |
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73 | |
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74 | For a simple example see the tests included in this distribution. |
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75 | |
76 | =head1 Attributes |
77 | |
78 | =head2 _plugin_ns |
79 | |
80 | String. The prefix to use for plugin names provided. MyApp::Plugin is sensible. |
81 | |
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82 | =head2 _plugin_app_ns |
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83 | |
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84 | ArrayRef, Accessor automatically dereferences into array on a read call. |
85 | By default will be filled with the class name and it's prescedents, it is used |
86 | to determine which directories to look for plugins as well as which plugins |
87 | take presedence upon namespace collitions. This allows you to subclass a pluggable |
88 | class and still use it's plugins while using yours first if they are available. |
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89 | |
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90 | =cut |
91 | |
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92 | =head2 _plugin_locator |
93 | |
94 | An automatically built instance of L<Module::Pluggable::Object> used to locate |
95 | available plugins. |
96 | |
97 | =cut |
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98 | |
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99 | #--------#---------#---------#---------#---------#---------#---------#---------# |
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100 | |
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101 | has _plugin_ns => |
102 | ( |
103 | is => 'rw', |
104 | required => 1, |
105 | isa => 'Str', |
106 | default => sub{ 'Plugin' }, |
107 | ); |
108 | |
109 | has _plugin_loaded => |
110 | ( |
111 | is => 'rw', |
112 | required => 1, |
113 | isa => 'HashRef', |
114 | default => sub{ {} } |
115 | ); |
116 | |
117 | has _plugin_app_ns => |
118 | ( |
119 | is => 'rw', |
120 | required => 1, |
121 | isa => 'ArrayRef', |
122 | lazy => 1, |
123 | auto_deref => 1, |
124 | builder => '_build_plugin_app_ns', |
125 | trigger => sub{ $_[0]->_clear_plugin_locator if $_[0]->_has_plugin_locator; }, |
126 | ); |
127 | |
128 | has _plugin_locator => |
129 | ( |
130 | is => 'rw', |
131 | required => 1, |
132 | lazy => 1, |
133 | isa => 'Module::Pluggable::Object', |
134 | clearer => '_clear_plugin_locator', |
135 | predicate => '_has_plugin_locator', |
136 | builder => '_build_plugin_locator' |
137 | ); |
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138 | |
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139 | #--------#---------#---------#---------#---------#---------#---------#---------# |
140 | |
141 | =head1 Public Methods |
142 | |
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143 | =head2 load_plugins @plugins |
144 | |
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145 | =head2 load_plugin $plugin |
146 | |
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147 | Load the apropriate role for C<$plugin>. |
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148 | |
149 | =cut |
150 | |
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151 | sub load_plugins { |
152 | my ($self, @plugins) = @_; |
153 | die("You must provide a plugin name") unless @plugins; |
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154 | |
155 | my $loaded = $self->_plugin_loaded; |
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156 | my @load = grep { not exists $loaded->{$_} } @plugins; |
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157 | my @roles = map { $self->_role_from_plugin($_) } @load; |
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158 | |
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159 | if ( $self->_load_and_apply_role(@roles) ) { |
160 | @{ $loaded }{@load} = @roles; |
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161 | return 1; |
162 | } else { |
163 | return; |
164 | } |
165 | } |
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166 | |
167 | |
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168 | sub load_plugin { |
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169 | my $self = shift; |
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170 | $self->load_plugins(@_); |
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171 | } |
172 | |
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173 | =head2 _original_class_name |
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174 | |
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175 | Because of the way roles apply C<$self-E<gt>blessed> and C<ref $self> will |
176 | no longer return what you expect. Instead use this class to get your original |
177 | class name. |
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178 | |
179 | =cut |
180 | |
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181 | sub _original_class_name{ |
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182 | my $self = shift; |
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183 | return (grep {$_ !~ /^Moose::/} $self->meta->class_precedence_list)[0]; |
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184 | } |
185 | |
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186 | |
187 | =head1 Private Methods |
188 | |
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189 | There's nothing stopping you from using these, but if you are using them |
190 | for anything thats not really complicated you are probably doing |
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191 | something wrong. |
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192 | |
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193 | =head2 _role_from_plugin $plugin |
194 | |
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195 | Creates a role name from a plugin name. If the plugin name is prepended |
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196 | with a C<+> it will be treated as a full name returned as is. Otherwise |
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197 | a string consisting of C<$plugin> prepended with the C<_plugin_ns> |
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198 | and the first valid value from C<_plugin_app_ns> will be returned. Example |
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199 | |
200 | #assuming appname MyApp and C<_plugin_ns> 'Plugin' |
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201 | $self->_role_from_plugin("MyPlugin"); # MyApp::Plugin::MyPlugin |
202 | |
203 | =cut |
204 | |
205 | sub _role_from_plugin{ |
206 | my ($self, $plugin) = @_; |
207 | |
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208 | return $1 if( $plugin =~ /^\+(.*)/ ); |
209 | |
210 | my $o = join '::', $self->_plugin_ns, $plugin; |
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211 | #Father, please forgive me for I have sinned. |
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212 | my @roles = grep{ /${o}$/ } $self->_plugin_locator->plugins; |
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213 | |
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214 | croak("Unable to locate plugin '$plugin'") unless @roles; |
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215 | return $roles[0] if @roles == 1; |
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216 | |
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217 | my $i = 0; |
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218 | my %presedence_list = map{ $i++; "${_}::${o}", $i } $self->_plugin_app_ns; |
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219 | |
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220 | @roles = sort{ $presedence_list{$a} <=> $presedence_list{$b}} @roles; |
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221 | |
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222 | return shift @roles; |
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223 | } |
224 | |
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225 | =head2 _load_and_apply_role @roles |
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226 | |
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227 | Require C<$role> if it is not already loaded and apply it. This is |
228 | the meat of this module. |
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229 | |
230 | =cut |
231 | |
232 | sub _load_and_apply_role{ |
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233 | my ($self, @roles) = @_; |
234 | die("You must provide a role name") unless @roles; |
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235 | |
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236 | foreach my $role ( @roles ) { |
237 | eval { Class::MOP::load_class($role) }; |
238 | confess("Failed to load role: ${role} $@") if $@; |
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239 | |
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240 | carp("Using 'override' is strongly discouraged and may not behave ". |
241 | "as you expect it to. Please use 'around'") |
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242 | if scalar keys %{ $role->meta->get_override_method_modifiers_map }; |
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243 | } |
244 | |
245 | Moose::Util::apply_all_roles( $self, @roles ); |
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246 | |
247 | return 1; |
248 | } |
249 | |
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250 | =head2 _build_plugin_app_ns |
251 | |
252 | Automatically builds the _plugin_app_ns attribute with the classes in the |
253 | class presedence list that are not part of Moose. |
254 | |
255 | =cut |
256 | |
257 | sub _build_plugin_app_ns{ |
258 | my $self = shift; |
259 | my @names = (grep {$_ !~ /^Moose::/} $self->meta->class_precedence_list); |
260 | return \@names; |
261 | } |
262 | |
263 | =head2 _build_plugin_locator |
264 | |
265 | Automatically creates a L<Module::Pluggable::Object> instance with the correct |
266 | search_path. |
267 | |
268 | =cut |
269 | |
270 | sub _build_plugin_locator{ |
271 | my $self = shift; |
272 | |
273 | my $locator = Module::Pluggable::Object->new |
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274 | ( search_path => |
275 | [ map { join '::', ($_, $self->_plugin_ns) } $self->_plugin_app_ns ] |
276 | ); |
277 | return $locator; |
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278 | } |
279 | |
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280 | =head2 meta |
281 | |
282 | Keep tests happy. See L<Moose> |
283 | |
284 | =cut |
285 | |
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286 | 1; |
287 | |
288 | __END__; |
289 | |
290 | =head1 SEE ALSO |
291 | |
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292 | L<Moose>, L<Moose::Role>, L<Class::Inspector> |
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293 | |
294 | =head1 AUTHOR |
295 | |
296 | Guillermo Roditi, <groditi@cpan.org> |
297 | |
298 | =head1 BUGS |
299 | |
300 | Holler? |
301 | |
302 | Please report any bugs or feature requests to |
303 | C<bug-moosex-object-pluggable at rt.cpan.org>, or through the web interface at |
304 | L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=MooseX-Object-Pluggable>. |
305 | I will be notified, and then you'll automatically be notified of progress on |
306 | your bug as I make changes. |
307 | |
308 | =head1 SUPPORT |
309 | |
310 | You can find documentation for this module with the perldoc command. |
311 | |
312 | perldoc MooseX-Object-Pluggable |
313 | |
314 | You can also look for information at: |
315 | |
316 | =over 4 |
317 | |
318 | =item * AnnoCPAN: Annotated CPAN documentation |
319 | |
320 | L<http://annocpan.org/dist/MooseX-Object-Pluggable> |
321 | |
322 | =item * CPAN Ratings |
323 | |
324 | L<http://cpanratings.perl.org/d/MooseX-Object-Pluggable> |
325 | |
326 | =item * RT: CPAN's request tracker |
327 | |
328 | L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=MooseX-Object-Pluggable> |
329 | |
330 | =item * Search CPAN |
331 | |
332 | L<http://search.cpan.org/dist/MooseX-Object-Pluggable> |
333 | |
334 | =back |
335 | |
336 | =head1 ACKNOWLEDGEMENTS |
337 | |
338 | =over 4 |
339 | |
340 | =item #Moose - Huge number of questions |
341 | |
342 | =item Matt S Trout <mst@shadowcatsystems.co.uk> - ideas / planning. |
343 | |
344 | =item Stevan Little - EVERYTHING. Without him this would have never happened. |
345 | |
346 | =back |
347 | |
348 | =head1 COPYRIGHT |
349 | |
350 | Copyright 2007 Guillermo Roditi. All Rights Reserved. This is |
351 | free software; you may redistribute it and/or modify it under the same |
352 | terms as Perl itself. |
353 | |
354 | =cut |