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c3398f5b |
1 | #!/usr/bin/env perl |
306290e8 |
2 | package Mouse::Meta::Attribute; |
c3398f5b |
3 | use strict; |
4 | use warnings; |
5 | |
6 | use Carp 'confess'; |
3301fa54 |
7 | use Scalar::Util 'blessed'; |
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8 | |
9 | sub new { |
10 | my $class = shift; |
11 | my %args = @_; |
12 | |
2e7e86c6 |
13 | my $name = $args{name}; |
14 | |
15 | $args{init_arg} = $name |
7ee01d77 |
16 | unless exists $args{init_arg}; |
45959ffa |
17 | |
c3398f5b |
18 | $args{is} ||= ''; |
19 | |
2e7e86c6 |
20 | if ($args{lazy_build}) { |
21 | confess("You can not use lazy_build and default for the same attribute $name") |
22 | if exists $args{default}; |
23 | $args{lazy} = 1; |
24 | $args{required} = 1; |
25 | $args{builder} ||= "_build_${name}"; |
26 | if ($name =~ /^_/) { |
27 | $args{clearer} ||= "_clear${name}"; |
28 | $args{predicate} ||= "_has${name}"; |
29 | } |
30 | else { |
31 | $args{clearer} ||= "clear_${name}"; |
32 | $args{predicate} ||= "has_${name}"; |
33 | } |
45959ffa |
34 | } |
35 | |
c3398f5b |
36 | bless \%args, $class; |
37 | } |
38 | |
3cf68001 |
39 | sub name { $_[0]->{name} } |
40 | sub class { $_[0]->{class} } |
41 | sub _is_metadata { $_[0]->{is} } |
42 | sub is_required { $_[0]->{required} } |
43 | sub default { $_[0]->{default} } |
44 | sub is_lazy { $_[0]->{lazy} } |
a5fe4015 |
45 | sub is_lazy_build { $_[0]->{lazy_build} } |
3cf68001 |
46 | sub predicate { $_[0]->{predicate} } |
47 | sub clearer { $_[0]->{clearer} } |
48 | sub handles { $_[0]->{handles} } |
49 | sub is_weak_ref { $_[0]->{weak_ref} } |
50 | sub init_arg { $_[0]->{init_arg} } |
51 | sub type_constraint { $_[0]->{type_constraint} } |
52 | sub trigger { $_[0]->{trigger} } |
53 | sub builder { $_[0]->{builder} } |
54 | sub should_auto_deref { $_[0]->{auto_deref} } |
c3398f5b |
55 | |
ccea8101 |
56 | sub has_default { exists $_[0]->{default} } |
57 | sub has_predicate { exists $_[0]->{predicate} } |
58 | sub has_clearer { exists $_[0]->{clearer} } |
59 | sub has_handles { exists $_[0]->{handles} } |
ccea8101 |
60 | sub has_type_constraint { exists $_[0]->{type_constraint} } |
de9a434a |
61 | sub has_trigger { exists $_[0]->{trigger} } |
62 | sub has_builder { exists $_[0]->{builder} } |
ccea8101 |
63 | |
1bfebf5f |
64 | sub _create_args { |
65 | $_[0]->{_create_args} = $_[1] if @_ > 1; |
66 | $_[0]->{_create_args} |
67 | } |
68 | |
c3398f5b |
69 | sub generate_accessor { |
70 | my $attribute = shift; |
71 | |
2434d21b |
72 | my $name = $attribute->name; |
f3c1ccc8 |
73 | my $key = $name; |
2434d21b |
74 | my $default = $attribute->default; |
75 | my $trigger = $attribute->trigger; |
76 | my $type = $attribute->type_constraint; |
5aa30ced |
77 | my $constraint = $attribute->find_type_constraint; |
9367e029 |
78 | my $builder = $attribute->builder; |
c3398f5b |
79 | |
80 | my $accessor = 'sub { |
81 | my $self = shift;'; |
82 | |
2434d21b |
83 | if ($attribute->_is_metadata eq 'rw') { |
c3398f5b |
84 | $accessor .= 'if (@_) { |
a707f587 |
85 | local $_ = $_[0];'; |
86 | |
87 | if ($constraint) { |
1f2b4780 |
88 | $accessor .= 'do { |
e8b3db47 |
89 | my $display = defined($_) ? overload::StrVal($_) : "undef"; |
1f2b4780 |
90 | Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display") unless $constraint->(); |
91 | };' |
a707f587 |
92 | } |
93 | |
94 | $accessor .= '$self->{$key} = $_;'; |
c3398f5b |
95 | |
3645b316 |
96 | if ($attribute->is_weak_ref) { |
97 | $accessor .= 'Scalar::Util::weaken($self->{$key}) if ref($self->{$key});'; |
c3398f5b |
98 | } |
99 | |
100 | if ($trigger) { |
a707f587 |
101 | $accessor .= '$trigger->($self, $_, $attribute);'; |
c3398f5b |
102 | } |
103 | |
104 | $accessor .= '}'; |
105 | } |
106 | else { |
636c002e |
107 | $accessor .= 'confess "Cannot assign a value to a read-only accessor" if @_;'; |
c3398f5b |
108 | } |
109 | |
2434d21b |
110 | if ($attribute->is_lazy) { |
c3398f5b |
111 | $accessor .= '$self->{$key} = '; |
9367e029 |
112 | |
113 | $accessor .= $attribute->has_builder |
114 | ? '$self->$builder' |
115 | : ref($default) eq 'CODE' |
116 | ? '$default->($self)' |
117 | : '$default'; |
118 | |
c3398f5b |
119 | $accessor .= ' if !exists($self->{$key});'; |
120 | } |
121 | |
3cf68001 |
122 | if ($attribute->should_auto_deref) { |
123 | if ($attribute->type_constraint eq 'ArrayRef') { |
124 | $accessor .= 'if (wantarray) { |
125 | return @{ $self->{$key} || [] }; |
126 | }'; |
127 | } |
128 | else { |
129 | $accessor .= 'if (wantarray) { |
130 | return %{ $self->{$key} || {} }; |
131 | }'; |
132 | } |
133 | } |
134 | |
135 | $accessor .= 'return $self->{$key}; |
c3398f5b |
136 | }'; |
137 | |
138 | return eval $accessor; |
139 | } |
140 | |
141 | sub generate_predicate { |
142 | my $attribute = shift; |
f3c1ccc8 |
143 | my $key = $attribute->name; |
c3398f5b |
144 | |
145 | my $predicate = 'sub { exists($_[0]->{$key}) }'; |
146 | |
147 | return eval $predicate; |
148 | } |
149 | |
150 | sub generate_clearer { |
151 | my $attribute = shift; |
f3c1ccc8 |
152 | my $key = $attribute->name; |
c3398f5b |
153 | |
154 | my $predicate = 'sub { delete($_[0]->{$key}) }'; |
155 | |
156 | return eval $predicate; |
157 | } |
158 | |
159 | sub generate_handles { |
160 | my $attribute = shift; |
2434d21b |
161 | my $reader = $attribute->name; |
c3cc3642 |
162 | my %handles = $attribute->_canonicalize_handles($attribute->handles); |
c3398f5b |
163 | |
164 | my %method_map; |
165 | |
c3cc3642 |
166 | for my $local_method (keys %handles) { |
167 | my $remote_method = $handles{$local_method}; |
c3398f5b |
168 | |
169 | my $method = 'sub { |
170 | my $self = shift; |
171 | $self->$reader->$remote_method(@_) |
172 | }'; |
173 | |
174 | $method_map{$local_method} = eval $method; |
175 | } |
176 | |
177 | return \%method_map; |
178 | } |
179 | |
180 | sub create { |
181 | my ($self, $class, $name, %args) = @_; |
182 | |
1bfebf5f |
183 | $args{name} = $name; |
184 | $args{class} = $class; |
185 | |
8fd9e611 |
186 | $self->validate_args($name, %args); |
45ea8620 |
187 | |
c021207d |
188 | $args{type_constraint} = delete $args{isa} |
189 | if exists $args{isa}; |
186657a9 |
190 | |
1bfebf5f |
191 | my $attribute = $self->new(%args); |
192 | $attribute->_create_args(\%args); |
193 | |
c3398f5b |
194 | my $meta = $class->meta; |
195 | |
b2500191 |
196 | $meta->add_attribute($attribute); |
197 | |
c3398f5b |
198 | # install an accessor |
2434d21b |
199 | if ($attribute->_is_metadata eq 'rw' || $attribute->_is_metadata eq 'ro') { |
c3398f5b |
200 | my $accessor = $attribute->generate_accessor; |
201 | no strict 'refs'; |
202 | *{ $class . '::' . $name } = $accessor; |
203 | } |
204 | |
c3398f5b |
205 | for my $method (qw/predicate clearer/) { |
2434d21b |
206 | my $predicate = "has_$method"; |
207 | if ($attribute->$predicate) { |
c3398f5b |
208 | my $generator = "generate_$method"; |
209 | my $coderef = $attribute->$generator; |
210 | no strict 'refs'; |
2434d21b |
211 | *{ $class . '::' . $attribute->$method } = $coderef; |
c3398f5b |
212 | } |
213 | } |
214 | |
2434d21b |
215 | if ($attribute->has_handles) { |
c3398f5b |
216 | my $method_map = $attribute->generate_handles; |
217 | for my $method_name (keys %$method_map) { |
218 | no strict 'refs'; |
219 | *{ $class . '::' . $method_name } = $method_map->{$method_name}; |
220 | } |
221 | } |
222 | |
223 | return $attribute; |
224 | } |
225 | |
8fd9e611 |
226 | sub validate_args { |
227 | my $self = shift; |
228 | my $name = shift; |
229 | my %args = @_; |
230 | |
231 | confess "You cannot have lazy attribute ($name) without specifying a default value for it" |
232 | if $args{lazy} && !exists($args{default}) && !exists($args{builder}); |
233 | |
234 | confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])" |
235 | if ref($args{default}) |
236 | && ref($args{default}) ne 'CODE'; |
237 | |
238 | confess "You cannot auto-dereference without specifying a type constraint on attribute $name" |
239 | if $args{auto_deref} && !exists($args{isa}); |
240 | |
241 | confess "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute $name" |
242 | if $args{auto_deref} |
243 | && $args{isa} ne 'ArrayRef' |
244 | && $args{isa} ne 'HashRef'; |
245 | |
246 | return 1; |
247 | } |
248 | |
5aa30ced |
249 | sub find_type_constraint { |
250 | my $self = shift; |
251 | my $type = $self->type_constraint; |
252 | |
253 | return unless $type; |
254 | |
255 | my $checker = Mouse::TypeRegistry->optimized_constraints->{$type}; |
256 | return $checker if $checker; |
257 | |
3301fa54 |
258 | return sub { blessed($_) && blessed($_) eq $type }; |
5aa30ced |
259 | } |
260 | |
261 | sub verify_type_constraint { |
262 | my $self = shift; |
263 | local $_ = shift; |
264 | |
265 | my $type = $self->type_constraint |
266 | or return 1; |
af745d5a |
267 | my $constraint = $self->find_type_constraint; |
5aa30ced |
268 | |
269 | return 1 if $constraint->($_); |
270 | |
271 | my $name = $self->name; |
f3e05dfd |
272 | my $display = defined($_) ? overload::StrVal($_) : 'undef'; |
273 | Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display"); |
5aa30ced |
274 | } |
275 | |
af745d5a |
276 | sub _canonicalize_handles { |
277 | my $self = shift; |
278 | my $handles = shift; |
279 | |
280 | if (ref($handles) eq 'HASH') { |
281 | return %$handles; |
282 | } |
283 | elsif (ref($handles) eq 'ARRAY') { |
284 | return map { $_ => $_ } @$handles; |
285 | } |
286 | else { |
287 | confess "Unable to canonicalize the 'handles' option with $handles"; |
288 | } |
289 | } |
290 | |
1bfebf5f |
291 | sub clone_parent { |
292 | my $self = shift; |
293 | my $class = shift; |
294 | my $name = shift; |
295 | my %args = ($self->get_parent_args($class, $name), @_); |
296 | |
297 | $self->create($class, $name, %args); |
298 | } |
299 | |
300 | sub get_parent_args { |
301 | my $self = shift; |
302 | my $class = shift; |
303 | my $name = shift; |
304 | |
305 | for my $super ($class->meta->linearized_isa) { |
bb733405 |
306 | my $super_attr = $super->can("meta") && $super->meta->get_attribute($name) |
1bfebf5f |
307 | or next; |
308 | return %{ $super_attr->_create_args }; |
309 | } |
310 | |
311 | confess "Could not find an attribute by the name of '$name' to inherit from"; |
312 | } |
313 | |
c3398f5b |
314 | 1; |
315 | |
316 | __END__ |
317 | |
318 | =head1 NAME |
319 | |
306290e8 |
320 | Mouse::Meta::Attribute - attribute metaclass |
c3398f5b |
321 | |
322 | =head1 METHODS |
323 | |
306290e8 |
324 | =head2 new %args -> Mouse::Meta::Attribute |
c3398f5b |
325 | |
306290e8 |
326 | Instantiates a new Mouse::Meta::Attribute. Does nothing else. |
c3398f5b |
327 | |
306290e8 |
328 | =head2 create OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute |
c3398f5b |
329 | |
330 | Creates a new attribute in OwnerClass. Accessors and helper methods are |
331 | installed. Some error checking is done. |
332 | |
333 | =head2 name -> AttributeName |
334 | |
335 | =head2 class -> OwnerClass |
336 | |
ab27a55e |
337 | =head2 is_required -> Bool |
c3398f5b |
338 | |
ab27a55e |
339 | =head2 default -> Item |
c3398f5b |
340 | |
ab27a55e |
341 | =head2 has_default -> Bool |
342 | |
343 | =head2 is_lazy -> Bool |
344 | |
345 | =head2 predicate -> MethodName | Undef |
346 | |
347 | =head2 has_predicate -> Bool |
348 | |
349 | =head2 clearer -> MethodName | Undef |
350 | |
351 | =head2 has_clearer -> Bool |
c3398f5b |
352 | |
353 | =head2 handles -> { LocalName => RemoteName } |
354 | |
ab27a55e |
355 | =head2 has_handles -> Bool |
356 | |
3645b316 |
357 | =head2 is_weak_ref -> Bool |
c3398f5b |
358 | |
359 | =head2 init_arg -> Str |
360 | |
ab27a55e |
361 | =head2 type_constraint -> Str |
362 | |
363 | =head2 has_type_constraint -> Bool |
364 | |
365 | =head2 trigger => CODE | Undef |
366 | |
367 | =head2 has_trigger -> Bool |
368 | |
369 | =head2 builder => MethodName | Undef |
370 | |
371 | =head2 has_builder -> Bool |
372 | |
0fff36e6 |
373 | =head2 should_auto_deref -> Bool |
374 | |
c3398f5b |
375 | Informational methods. |
376 | |
377 | =head2 generate_accessor -> CODE |
378 | |
379 | Creates a new code reference for the attribute's accessor. |
380 | |
381 | =head2 generate_predicate -> CODE |
382 | |
383 | Creates a new code reference for the attribute's predicate. |
384 | |
385 | =head2 generate_clearer -> CODE |
386 | |
387 | Creates a new code reference for the attribute's clearer. |
388 | |
389 | =head2 generate_handles -> { MethodName => CODE } |
390 | |
391 | Creates a new code reference for each of the attribute's handles methods. |
392 | |
fb706f5c |
393 | =head2 find_type_constraint -> CODE |
394 | |
395 | Returns a code reference which can be used to check that a given value passes |
396 | this attribute's type constraint; |
397 | |
398 | =head2 verify_type_constraint Item -> 1 | ERROR |
399 | |
400 | Checks that the given value passes this attribute's type constraint. Returns 1 |
401 | on success, otherwise C<confess>es. |
402 | |
c3398f5b |
403 | =cut |
404 | |