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1 | package Moose::Role; |
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2 | use strict; |
3 | use warnings; |
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4 | |
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5 | use Scalar::Util 'blessed'; |
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6 | use Carp 'croak'; |
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7 | use Class::Load 'is_class_loaded'; |
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8 | |
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9 | use Sub::Exporter; |
10 | |
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11 | use Moose (); |
12 | use Moose::Util (); |
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13 | |
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14 | use Moose::Exporter; |
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15 | use Moose::Meta::Role; |
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16 | use Moose::Util::TypeConstraints; |
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17 | |
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18 | sub extends { |
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19 | croak "Roles do not support 'extends' (you can use 'with' to specialize a role)"; |
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20 | } |
21 | |
22 | sub with { |
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23 | Moose::Util::apply_all_roles( shift, @_ ); |
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24 | } |
25 | |
26 | sub requires { |
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27 | my $meta = shift; |
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28 | croak "Must specify at least one method" unless @_; |
29 | $meta->add_required_methods(@_); |
30 | } |
31 | |
32 | sub excludes { |
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33 | my $meta = shift; |
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34 | croak "Must specify at least one role" unless @_; |
35 | $meta->add_excluded_roles(@_); |
36 | } |
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37 | |
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38 | sub has { |
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39 | my $meta = shift; |
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40 | my $name = shift; |
41 | croak 'Usage: has \'name\' => ( key => value, ... )' if @_ == 1; |
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42 | my %options = ( definition_context => Moose::Util::_caller_info(), @_ ); |
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43 | my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ]; |
44 | $meta->add_attribute( $_, %options ) for @$attrs; |
45 | } |
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46 | |
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47 | sub _add_method_modifier { |
48 | my $type = shift; |
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49 | my $meta = shift; |
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50 | |
51 | if ( ref($_[0]) eq 'Regexp' ) { |
52 | croak "Roles do not currently support regex " |
53 | . " references for $type method modifiers"; |
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54 | } |
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55 | |
56 | Moose::Util::add_method_modifier($meta, $type, \@_); |
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57 | } |
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58 | |
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59 | sub before { _add_method_modifier('before', @_) } |
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60 | |
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61 | sub after { _add_method_modifier('after', @_) } |
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62 | |
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63 | sub around { _add_method_modifier('around', @_) } |
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64 | |
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65 | # see Moose.pm for discussion |
66 | sub super { |
67 | return unless $Moose::SUPER_BODY; |
68 | $Moose::SUPER_BODY->(@Moose::SUPER_ARGS); |
69 | } |
70 | |
71 | sub override { |
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72 | my $meta = shift; |
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73 | my ( $name, $code ) = @_; |
74 | $meta->add_override_method_modifier( $name, $code ); |
75 | } |
76 | |
77 | sub inner { |
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78 | croak "Roles cannot support 'inner'"; |
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79 | } |
80 | |
81 | sub augment { |
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82 | croak "Roles cannot support 'augment'"; |
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83 | } |
84 | |
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85 | Moose::Exporter->setup_import_methods( |
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86 | with_meta => [ |
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87 | qw( with requires excludes has before after around override ) |
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88 | ], |
89 | as_is => [ |
90 | qw( extends super inner augment ), |
91 | \&Carp::confess, |
92 | \&Scalar::Util::blessed, |
93 | ], |
94 | ); |
95 | |
96 | sub init_meta { |
97 | shift; |
98 | my %args = @_; |
99 | |
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100 | my $role = $args{for_class}; |
101 | |
102 | unless ($role) { |
103 | require Moose; |
104 | Moose->throw_error("Cannot call init_meta without specifying a for_class"); |
105 | } |
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106 | |
107 | my $metaclass = $args{metaclass} || "Moose::Meta::Role"; |
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108 | my $meta_name = exists $args{meta_name} ? $args{meta_name} : 'meta'; |
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109 | |
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110 | Moose->throw_error("The Metaclass $metaclass must be loaded. (Perhaps you forgot to 'use $metaclass'?)") |
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111 | unless is_class_loaded($metaclass); |
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112 | |
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113 | Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Role.") |
114 | unless $metaclass->isa('Moose::Meta::Role'); |
115 | |
116 | # make a subtype for each Moose role |
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117 | role_type $role unless find_type_constraint($role); |
118 | |
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119 | my $meta; |
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120 | if ( $meta = Class::MOP::get_metaclass_by_name($role) ) { |
121 | unless ( $meta->isa("Moose::Meta::Role") ) { |
122 | my $error_message = "$role already has a metaclass, but it does not inherit $metaclass ($meta)."; |
123 | if ( $meta->isa('Moose::Meta::Class') ) { |
124 | Moose->throw_error($error_message . ' You cannot make the same thing a role and a class. Remove either Moose or Moose::Role.'); |
125 | } else { |
126 | Moose->throw_error($error_message); |
127 | } |
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128 | } |
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129 | } |
130 | else { |
131 | $meta = $metaclass->initialize($role); |
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132 | } |
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133 | |
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134 | if (defined $meta_name) { |
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135 | # also check for inherited non moose 'meta' method? |
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136 | my $existing = $meta->get_method($meta_name); |
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137 | if ($existing && !$existing->isa('Class::MOP::Method::Meta')) { |
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138 | Carp::cluck "Moose::Role is overwriting an existing method named " |
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139 | . "$meta_name in role $role with a method " |
140 | . "which returns the class's metaclass. If this is " |
141 | . "actually what you want, you should remove the " |
142 | . "existing method, otherwise, you should rename or " |
143 | . "disable this generated method using the " |
144 | . "'-meta_name' option to 'use Moose::Role'."; |
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145 | } |
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146 | $meta->_add_meta_method($meta_name); |
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147 | } |
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148 | |
149 | return $meta; |
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150 | } |
151 | |
152 | 1; |
153 | |
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154 | # ABSTRACT: The Moose Role |
155 | |
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156 | __END__ |
157 | |
158 | =pod |
159 | |
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160 | =head1 SYNOPSIS |
161 | |
162 | package Eq; |
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163 | use Moose::Role; # automatically turns on strict and warnings |
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164 | |
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165 | requires 'equal'; |
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166 | |
167 | sub no_equal { |
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168 | my ($self, $other) = @_; |
169 | !$self->equal($other); |
170 | } |
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171 | |
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172 | # ... then in your classes |
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173 | |
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174 | package Currency; |
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175 | use Moose; # automatically turns on strict and warnings |
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176 | |
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177 | with 'Eq'; |
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178 | |
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179 | sub equal { |
180 | my ($self, $other) = @_; |
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181 | $self->as_float == $other->as_float; |
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182 | } |
183 | |
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184 | # ... and also |
185 | |
186 | package Comparator; |
187 | use Moose; |
188 | |
189 | has compare_to => ( |
190 | is => 'ro', |
191 | does => 'Eq', |
192 | handles => 'Eq', |
193 | ); |
194 | |
195 | # ... which allows |
196 | |
197 | my $currency1 = Currency->new(...); |
198 | my $currency2 = Currency->new(...); |
199 | Comparator->new(compare_to => $currency1)->equal($currency2); |
200 | |
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201 | =head1 DESCRIPTION |
202 | |
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203 | The concept of roles is documented in L<Moose::Manual::Roles>. This document |
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204 | serves as API documentation. |
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205 | |
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206 | =head1 EXPORTED FUNCTIONS |
207 | |
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208 | Moose::Role currently supports all of the functions that L<Moose> exports, but |
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209 | differs slightly in how some items are handled (see L</CAVEATS> below for |
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210 | details). |
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211 | |
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212 | Moose::Role also offers two role-specific keyword exports: |
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213 | |
214 | =over 4 |
215 | |
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216 | =item B<requires (@method_names)> |
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217 | |
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218 | Roles can require that certain methods are implemented by any class which |
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219 | C<does> the role. |
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220 | |
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221 | Note that attribute accessors also count as methods for the purposes |
222 | of satisfying the requirements of a role. |
223 | |
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224 | =item B<excludes (@role_names)> |
225 | |
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226 | Roles can C<exclude> other roles, in effect saying "I can never be combined |
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227 | with these C<@role_names>". This is a feature which should not be used |
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228 | lightly. |
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229 | |
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230 | =back |
231 | |
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232 | =head2 B<unimport> |
233 | |
234 | Moose::Role offers a way to remove the keywords it exports, through the |
235 | C<unimport> method. You simply have to say C<no Moose::Role> at the bottom of |
236 | your code for this to work. |
237 | |
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238 | =head1 METACLASS |
239 | |
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240 | When you use Moose::Role, you can specify traits which will be applied to your |
241 | role metaclass: |
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242 | |
243 | use Moose::Role -traits => 'My::Trait'; |
244 | |
245 | This is very similar to the attribute traits feature. When you do |
246 | this, your class's C<meta> object will have the specified traits |
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247 | applied to it. See L<Moose/Metaclass and Trait Name Resolution> for more |
248 | details. |
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249 | |
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250 | =head1 APPLYING ROLES |
251 | |
252 | In addition to being applied to a class using the 'with' syntax (see |
253 | L<Moose::Manual::Roles>) and using the L<Moose::Util> 'apply_all_roles' |
254 | method, roles may also be applied to an instance of a class using |
255 | L<Moose::Util> 'apply_all_roles' or the role's metaclass: |
256 | |
257 | MyApp::Test::SomeRole->meta->apply( $instance ); |
258 | |
259 | Doing this creates a new, mutable, anonymous subclass, applies the role to that, |
260 | and reblesses. In a debugger, for example, you will see class names of the |
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261 | form C< Moose::Meta::Class::__ANON__::SERIAL::6 >, which means that doing a |
262 | 'ref' on your instance may not return what you expect. See L<Moose::Object> for |
263 | 'DOES'. |
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264 | |
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265 | Additional params may be added to the new instance by providing |
266 | 'rebless_params'. See L<Moose::Meta::Role::Application::ToInstance>. |
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267 | |
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268 | =head1 CAVEATS |
269 | |
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270 | Role support has only a few caveats: |
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271 | |
272 | =over 4 |
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273 | |
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274 | =item * |
275 | |
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276 | Roles cannot use the C<extends> keyword; it will throw an exception for now. |
277 | The same is true of the C<augment> and C<inner> keywords (not sure those |
278 | really make sense for roles). All other Moose keywords will be I<deferred> |
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279 | so that they can be applied to the consuming class. |
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280 | |
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281 | =item * |
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282 | |
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283 | Role composition does its best to B<not> be order-sensitive when it comes to |
284 | conflict resolution and requirements detection. However, it is order-sensitive |
285 | when it comes to method modifiers. All before/around/after modifiers are |
286 | included whenever a role is composed into a class, and then applied in the order |
287 | in which the roles are used. This also means that there is no conflict for |
288 | before/around/after modifiers. |
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289 | |
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290 | In most cases, this will be a non-issue; however, it is something to keep in |
291 | mind when using method modifiers in a role. You should never assume any |
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292 | ordering. |
293 | |
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294 | =back |
295 | |
296 | =head1 BUGS |
297 | |
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298 | See L<Moose/BUGS> for details on reporting bugs. |
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299 | |
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300 | =cut |