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1 | #!/usr/bin/env perl |
2 | package Mouse::Attribute; |
3 | use strict; |
4 | use warnings; |
5 | |
6 | use Carp 'confess'; |
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7 | use Scalar::Util 'blessed'; |
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8 | |
9 | sub new { |
10 | my $class = shift; |
11 | my %args = @_; |
12 | |
7ee01d77 |
13 | $args{init_arg} = $args{name} |
14 | unless exists $args{init_arg}; |
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15 | $args{is} ||= ''; |
16 | |
17 | bless \%args, $class; |
18 | } |
19 | |
186657a9 |
20 | sub name { $_[0]->{name} } |
21 | sub class { $_[0]->{class} } |
2434d21b |
22 | sub _is_metadata { $_[0]->{is} } |
23 | sub is_required { $_[0]->{required} } |
186657a9 |
24 | sub default { $_[0]->{default} } |
2434d21b |
25 | sub is_lazy { $_[0]->{lazy} } |
186657a9 |
26 | sub predicate { $_[0]->{predicate} } |
27 | sub clearer { $_[0]->{clearer} } |
28 | sub handles { $_[0]->{handles} } |
29 | sub weak_ref { $_[0]->{weak_ref} } |
30 | sub init_arg { $_[0]->{init_arg} } |
31 | sub type_constraint { $_[0]->{type_constraint} } |
de9a434a |
32 | sub trigger { $_[0]->{trigger} } |
33 | sub builder { $_[0]->{builder} } |
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34 | |
ccea8101 |
35 | sub has_default { exists $_[0]->{default} } |
36 | sub has_predicate { exists $_[0]->{predicate} } |
37 | sub has_clearer { exists $_[0]->{clearer} } |
38 | sub has_handles { exists $_[0]->{handles} } |
ccea8101 |
39 | sub has_type_constraint { exists $_[0]->{type_constraint} } |
de9a434a |
40 | sub has_trigger { exists $_[0]->{trigger} } |
41 | sub has_builder { exists $_[0]->{builder} } |
ccea8101 |
42 | |
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43 | sub generate_accessor { |
44 | my $attribute = shift; |
45 | |
2434d21b |
46 | my $name = $attribute->name; |
47 | my $key = $attribute->init_arg; |
48 | my $default = $attribute->default; |
49 | my $trigger = $attribute->trigger; |
50 | my $type = $attribute->type_constraint; |
5aa30ced |
51 | my $constraint = $attribute->find_type_constraint; |
9367e029 |
52 | my $builder = $attribute->builder; |
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53 | |
54 | my $accessor = 'sub { |
55 | my $self = shift;'; |
56 | |
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57 | if ($attribute->_is_metadata eq 'rw') { |
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58 | $accessor .= 'if (@_) { |
a707f587 |
59 | local $_ = $_[0];'; |
60 | |
61 | if ($constraint) { |
1f2b4780 |
62 | $accessor .= 'do { |
63 | my $display = defined($_) ? $_ : "undef"; |
64 | Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display") unless $constraint->(); |
65 | };' |
a707f587 |
66 | } |
67 | |
68 | $accessor .= '$self->{$key} = $_;'; |
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69 | |
2434d21b |
70 | if ($attribute->weak_ref) { |
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71 | $accessor .= 'Scalar::Util::weaken($self->{$key});'; |
72 | } |
73 | |
74 | if ($trigger) { |
a707f587 |
75 | $accessor .= '$trigger->($self, $_, $attribute);'; |
c3398f5b |
76 | } |
77 | |
78 | $accessor .= '}'; |
79 | } |
80 | else { |
636c002e |
81 | $accessor .= 'confess "Cannot assign a value to a read-only accessor" if @_;'; |
c3398f5b |
82 | } |
83 | |
2434d21b |
84 | if ($attribute->is_lazy) { |
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85 | $accessor .= '$self->{$key} = '; |
9367e029 |
86 | |
87 | $accessor .= $attribute->has_builder |
88 | ? '$self->$builder' |
89 | : ref($default) eq 'CODE' |
90 | ? '$default->($self)' |
91 | : '$default'; |
92 | |
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93 | $accessor .= ' if !exists($self->{$key});'; |
94 | } |
95 | |
96 | $accessor .= 'return $self->{$key} |
97 | }'; |
98 | |
99 | return eval $accessor; |
100 | } |
101 | |
102 | sub generate_predicate { |
103 | my $attribute = shift; |
2434d21b |
104 | my $key = $attribute->init_arg; |
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105 | |
106 | my $predicate = 'sub { exists($_[0]->{$key}) }'; |
107 | |
108 | return eval $predicate; |
109 | } |
110 | |
111 | sub generate_clearer { |
112 | my $attribute = shift; |
2434d21b |
113 | my $key = $attribute->init_arg; |
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114 | |
115 | my $predicate = 'sub { delete($_[0]->{$key}) }'; |
116 | |
117 | return eval $predicate; |
118 | } |
119 | |
120 | sub generate_handles { |
121 | my $attribute = shift; |
2434d21b |
122 | my $reader = $attribute->name; |
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123 | |
124 | my %method_map; |
125 | |
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126 | for my $local_method (keys %{ $attribute->handles }) { |
127 | my $remote_method = $attribute->handles->{$local_method}; |
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128 | |
129 | my $method = 'sub { |
130 | my $self = shift; |
131 | $self->$reader->$remote_method(@_) |
132 | }'; |
133 | |
134 | $method_map{$local_method} = eval $method; |
135 | } |
136 | |
137 | return \%method_map; |
138 | } |
139 | |
140 | sub create { |
141 | my ($self, $class, $name, %args) = @_; |
142 | |
143 | confess "You must specify a default for lazy attribute '$name'" |
9367e029 |
144 | if $args{lazy} && !exists($args{default}) && !exists($args{builder}); |
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145 | |
146 | confess "Trigger is not allowed on read-only attribute '$name'" |
147 | if $args{trigger} && $args{is} ne 'rw'; |
148 | |
149 | confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])" |
150 | if ref($args{default}) |
151 | && ref($args{default}) ne 'CODE'; |
152 | |
af745d5a |
153 | $args{handles} = { $self->_canonicalize_handles($args{handles}) } |
154 | if $args{handles}; |
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155 | |
c021207d |
156 | $args{type_constraint} = delete $args{isa} |
157 | if exists $args{isa}; |
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158 | |
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159 | my $attribute = $self->new(%args, name => $name, class => $class); |
160 | my $meta = $class->meta; |
161 | |
b2500191 |
162 | $meta->add_attribute($attribute); |
163 | |
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164 | # install an accessor |
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165 | if ($attribute->_is_metadata eq 'rw' || $attribute->_is_metadata eq 'ro') { |
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166 | my $accessor = $attribute->generate_accessor; |
167 | no strict 'refs'; |
168 | *{ $class . '::' . $name } = $accessor; |
169 | } |
170 | |
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171 | for my $method (qw/predicate clearer/) { |
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172 | my $predicate = "has_$method"; |
173 | if ($attribute->$predicate) { |
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174 | my $generator = "generate_$method"; |
175 | my $coderef = $attribute->$generator; |
176 | no strict 'refs'; |
2434d21b |
177 | *{ $class . '::' . $attribute->$method } = $coderef; |
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178 | } |
179 | } |
180 | |
2434d21b |
181 | if ($attribute->has_handles) { |
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182 | my $method_map = $attribute->generate_handles; |
183 | for my $method_name (keys %$method_map) { |
184 | no strict 'refs'; |
185 | *{ $class . '::' . $method_name } = $method_map->{$method_name}; |
186 | } |
187 | } |
188 | |
189 | return $attribute; |
190 | } |
191 | |
5aa30ced |
192 | sub find_type_constraint { |
193 | my $self = shift; |
194 | my $type = $self->type_constraint; |
195 | |
196 | return unless $type; |
197 | |
198 | my $checker = Mouse::TypeRegistry->optimized_constraints->{$type}; |
199 | return $checker if $checker; |
200 | |
3301fa54 |
201 | return sub { blessed($_) && blessed($_) eq $type }; |
5aa30ced |
202 | } |
203 | |
204 | sub verify_type_constraint { |
205 | my $self = shift; |
206 | local $_ = shift; |
207 | |
208 | my $type = $self->type_constraint |
209 | or return 1; |
af745d5a |
210 | my $constraint = $self->find_type_constraint; |
5aa30ced |
211 | |
212 | return 1 if $constraint->($_); |
213 | |
214 | my $name = $self->name; |
1f2b4780 |
215 | local $_ = "undef" unless defined($_); |
5aa30ced |
216 | Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $_"); |
217 | } |
218 | |
af745d5a |
219 | sub _canonicalize_handles { |
220 | my $self = shift; |
221 | my $handles = shift; |
222 | |
223 | if (ref($handles) eq 'HASH') { |
224 | return %$handles; |
225 | } |
226 | elsif (ref($handles) eq 'ARRAY') { |
227 | return map { $_ => $_ } @$handles; |
228 | } |
229 | else { |
230 | confess "Unable to canonicalize the 'handles' option with $handles"; |
231 | } |
232 | } |
233 | |
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234 | 1; |
235 | |
236 | __END__ |
237 | |
238 | =head1 NAME |
239 | |
240 | Mouse::Attribute - attribute metaclass |
241 | |
242 | =head1 METHODS |
243 | |
244 | =head2 new %args -> Mouse::Attribute |
245 | |
246 | Instantiates a new Mouse::Attribute. Does nothing else. |
247 | |
248 | =head2 create OwnerClass, AttributeName, %args -> Mouse::Attribute |
249 | |
250 | Creates a new attribute in OwnerClass. Accessors and helper methods are |
251 | installed. Some error checking is done. |
252 | |
253 | =head2 name -> AttributeName |
254 | |
255 | =head2 class -> OwnerClass |
256 | |
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257 | =head2 is_required -> Bool |
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258 | |
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259 | =head2 default -> Item |
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260 | |
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261 | =head2 has_default -> Bool |
262 | |
263 | =head2 is_lazy -> Bool |
264 | |
265 | =head2 predicate -> MethodName | Undef |
266 | |
267 | =head2 has_predicate -> Bool |
268 | |
269 | =head2 clearer -> MethodName | Undef |
270 | |
271 | =head2 has_clearer -> Bool |
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272 | |
273 | =head2 handles -> { LocalName => RemoteName } |
274 | |
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275 | =head2 has_handles -> Bool |
276 | |
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277 | =head2 weak_ref -> Bool |
278 | |
279 | =head2 init_arg -> Str |
280 | |
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281 | =head2 type_constraint -> Str |
282 | |
283 | =head2 has_type_constraint -> Bool |
284 | |
285 | =head2 trigger => CODE | Undef |
286 | |
287 | =head2 has_trigger -> Bool |
288 | |
289 | =head2 builder => MethodName | Undef |
290 | |
291 | =head2 has_builder -> Bool |
292 | |
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293 | Informational methods. |
294 | |
295 | =head2 generate_accessor -> CODE |
296 | |
297 | Creates a new code reference for the attribute's accessor. |
298 | |
299 | =head2 generate_predicate -> CODE |
300 | |
301 | Creates a new code reference for the attribute's predicate. |
302 | |
303 | =head2 generate_clearer -> CODE |
304 | |
305 | Creates a new code reference for the attribute's clearer. |
306 | |
307 | =head2 generate_handles -> { MethodName => CODE } |
308 | |
309 | Creates a new code reference for each of the attribute's handles methods. |
310 | |
fb706f5c |
311 | =head2 find_type_constraint -> CODE |
312 | |
313 | Returns a code reference which can be used to check that a given value passes |
314 | this attribute's type constraint; |
315 | |
316 | =head2 verify_type_constraint Item -> 1 | ERROR |
317 | |
318 | Checks that the given value passes this attribute's type constraint. Returns 1 |
319 | on success, otherwise C<confess>es. |
320 | |
c3398f5b |
321 | =cut |
322 | |