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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 | |
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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 | |
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20 | sub name { $_[0]->{name} } |
21 | sub class { $_[0]->{class} } |
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22 | sub _is_metadata { $_[0]->{is} } |
23 | sub is_required { $_[0]->{required} } |
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24 | sub default { $_[0]->{default} } |
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25 | sub is_lazy { $_[0]->{lazy} } |
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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} } |
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32 | sub trigger { $_[0]->{trigger} } |
33 | sub builder { $_[0]->{builder} } |
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34 | |
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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} } |
39 | sub has_weak_ref { exists $_[0]->{weak_ref} } |
40 | sub has_init_arg { exists $_[0]->{init_arg} } |
41 | sub has_type_constraint { exists $_[0]->{type_constraint} } |
de9a434a |
42 | sub has_trigger { exists $_[0]->{trigger} } |
43 | sub has_builder { exists $_[0]->{builder} } |
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44 | |
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45 | sub generate_accessor { |
46 | my $attribute = shift; |
47 | |
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48 | my $name = $attribute->name; |
49 | my $key = $attribute->init_arg; |
50 | my $default = $attribute->default; |
51 | my $trigger = $attribute->trigger; |
52 | my $type = $attribute->type_constraint; |
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53 | my $constraint = $attribute->find_type_constraint; |
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54 | |
55 | my $accessor = 'sub { |
56 | my $self = shift;'; |
57 | |
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58 | if ($attribute->_is_metadata eq 'rw') { |
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59 | $accessor .= 'if (@_) { |
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60 | local $_ = $_[0];'; |
61 | |
62 | if ($constraint) { |
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63 | $accessor .= 'do { |
64 | my $display = defined($_) ? $_ : "undef"; |
65 | Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display") unless $constraint->(); |
66 | };' |
a707f587 |
67 | } |
68 | |
69 | $accessor .= '$self->{$key} = $_;'; |
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70 | |
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71 | if ($attribute->weak_ref) { |
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72 | $accessor .= 'Scalar::Util::weaken($self->{$key});'; |
73 | } |
74 | |
75 | if ($trigger) { |
a707f587 |
76 | $accessor .= '$trigger->($self, $_, $attribute);'; |
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77 | } |
78 | |
79 | $accessor .= '}'; |
80 | } |
81 | else { |
82 | } |
83 | |
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84 | if ($attribute->is_lazy) { |
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85 | $accessor .= '$self->{$key} = '; |
2434d21b |
86 | $accessor .= ref($default) eq 'CODE' |
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87 | ? '$default->($self)' |
88 | : '$default'; |
89 | $accessor .= ' if !exists($self->{$key});'; |
90 | } |
91 | |
92 | $accessor .= 'return $self->{$key} |
93 | }'; |
94 | |
95 | return eval $accessor; |
96 | } |
97 | |
98 | sub generate_predicate { |
99 | my $attribute = shift; |
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100 | my $key = $attribute->init_arg; |
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101 | |
102 | my $predicate = 'sub { exists($_[0]->{$key}) }'; |
103 | |
104 | return eval $predicate; |
105 | } |
106 | |
107 | sub generate_clearer { |
108 | my $attribute = shift; |
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109 | my $key = $attribute->init_arg; |
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110 | |
111 | my $predicate = 'sub { delete($_[0]->{$key}) }'; |
112 | |
113 | return eval $predicate; |
114 | } |
115 | |
116 | sub generate_handles { |
117 | my $attribute = shift; |
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118 | my $reader = $attribute->name; |
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119 | |
120 | my %method_map; |
121 | |
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122 | for my $local_method (keys %{ $attribute->handles }) { |
123 | my $remote_method = $attribute->handles->{$local_method}; |
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124 | |
125 | my $method = 'sub { |
126 | my $self = shift; |
127 | $self->$reader->$remote_method(@_) |
128 | }'; |
129 | |
130 | $method_map{$local_method} = eval $method; |
131 | } |
132 | |
133 | return \%method_map; |
134 | } |
135 | |
136 | sub create { |
137 | my ($self, $class, $name, %args) = @_; |
138 | |
139 | confess "You must specify a default for lazy attribute '$name'" |
140 | if $args{lazy} && !exists($args{default}); |
141 | |
142 | confess "Trigger is not allowed on read-only attribute '$name'" |
143 | if $args{trigger} && $args{is} ne 'rw'; |
144 | |
145 | confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])" |
146 | if ref($args{default}) |
147 | && ref($args{default}) ne 'CODE'; |
148 | |
149 | $args{handles} = { map { $_ => $_ } @{ $args{handles} } } |
150 | if $args{handles} |
151 | && ref($args{handles}) eq 'ARRAY'; |
152 | |
153 | confess "You must pass a HASH or ARRAY to handles" |
154 | if exists($args{handles}) |
155 | && ref($args{handles}) ne 'HASH'; |
156 | |
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157 | $args{type_constraint} = delete $args{isa}; |
158 | |
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159 | my $attribute = $self->new(%args, name => $name, class => $class); |
160 | my $meta = $class->meta; |
161 | |
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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'; |
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177 | *{ $class . '::' . $attribute->$method } = $coderef; |
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178 | } |
179 | } |
180 | |
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181 | if ($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 | |
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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 $checker; |
200 | |
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201 | return sub { blessed($_) && blessed($_) eq $type }; |
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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; |
210 | my $constraint = $self->find_type_constraint |
211 | or return 1; |
212 | |
213 | return 1 if $constraint->($_); |
214 | |
215 | my $name = $self->name; |
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216 | local $_ = "undef" unless defined($_); |
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217 | Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $_"); |
218 | } |
219 | |
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220 | 1; |
221 | |
222 | __END__ |
223 | |
224 | =head1 NAME |
225 | |
226 | Mouse::Attribute - attribute metaclass |
227 | |
228 | =head1 METHODS |
229 | |
230 | =head2 new %args -> Mouse::Attribute |
231 | |
232 | Instantiates a new Mouse::Attribute. Does nothing else. |
233 | |
234 | =head2 create OwnerClass, AttributeName, %args -> Mouse::Attribute |
235 | |
236 | Creates a new attribute in OwnerClass. Accessors and helper methods are |
237 | installed. Some error checking is done. |
238 | |
239 | =head2 name -> AttributeName |
240 | |
241 | =head2 class -> OwnerClass |
242 | |
243 | =head2 default -> Value |
244 | |
245 | =head2 predicate -> MethodName |
246 | |
247 | =head2 clearer -> MethodName |
248 | |
249 | =head2 handles -> { LocalName => RemoteName } |
250 | |
251 | =head2 weak_ref -> Bool |
252 | |
253 | =head2 init_arg -> Str |
254 | |
255 | Informational methods. |
256 | |
257 | =head2 generate_accessor -> CODE |
258 | |
259 | Creates a new code reference for the attribute's accessor. |
260 | |
261 | =head2 generate_predicate -> CODE |
262 | |
263 | Creates a new code reference for the attribute's predicate. |
264 | |
265 | =head2 generate_clearer -> CODE |
266 | |
267 | Creates a new code reference for the attribute's clearer. |
268 | |
269 | =head2 generate_handles -> { MethodName => CODE } |
270 | |
271 | Creates a new code reference for each of the attribute's handles methods. |
272 | |
273 | =cut |
274 | |