Commit | Line | Data |
c0e30cf5 |
1 | |
2 | package Moose::Meta::Attribute; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
78cd1d3b |
7 | use Scalar::Util 'blessed', 'weaken', 'reftype'; |
a15dff8d |
8 | use Carp 'confess'; |
9 | |
4c4fbe56 |
10 | our $VERSION = '0.05'; |
78cd1d3b |
11 | |
a3c7e2fe |
12 | use Moose::Util::TypeConstraints (); |
bc1e29b5 |
13 | |
c0e30cf5 |
14 | use base 'Class::MOP::Attribute'; |
15 | |
ca01a97b |
16 | __PACKAGE__->meta->add_attribute('required' => (reader => 'is_required' )); |
17 | __PACKAGE__->meta->add_attribute('lazy' => (reader => 'is_lazy' )); |
6ba6d68c |
18 | __PACKAGE__->meta->add_attribute('coerce' => (reader => 'should_coerce')); |
19 | __PACKAGE__->meta->add_attribute('weak_ref' => (reader => 'is_weak_ref' )); |
82168dbb |
20 | __PACKAGE__->meta->add_attribute('type_constraint' => ( |
21 | reader => 'type_constraint', |
22 | predicate => 'has_type_constraint', |
23 | )); |
8c9d74e7 |
24 | __PACKAGE__->meta->add_attribute('trigger' => ( |
25 | reader => 'trigger', |
26 | predicate => 'has_trigger', |
27 | )); |
82168dbb |
28 | |
78cd1d3b |
29 | sub new { |
30 | my ($class, $name, %options) = @_; |
31 | |
32 | if (exists $options{is}) { |
33 | if ($options{is} eq 'ro') { |
34 | $options{reader} = $name; |
8c9d74e7 |
35 | (!exists $options{trigger}) |
36 | || confess "Cannot have a trigger on a read-only attribute"; |
78cd1d3b |
37 | } |
38 | elsif ($options{is} eq 'rw') { |
39 | $options{accessor} = $name; |
7eaef7ad |
40 | ((reftype($options{trigger}) || '') eq 'CODE') |
8c9d74e7 |
41 | || confess "A trigger must be a CODE reference" |
42 | if exists $options{trigger}; |
78cd1d3b |
43 | } |
44 | } |
45 | |
46 | if (exists $options{isa}) { |
02a0fb52 |
47 | |
48 | if (exists $options{does}) { |
49 | if (eval { $options{isa}->can('does') }) { |
50 | ($options{isa}->does($options{does})) |
51 | || confess "Cannot have an isa option and a does option if the isa does not do the does"; |
52 | } |
7eaef7ad |
53 | else { |
54 | confess "Cannot have an isa option which cannot ->does()"; |
55 | } |
02a0fb52 |
56 | } |
57 | |
78cd1d3b |
58 | # allow for anon-subtypes here ... |
59 | if (blessed($options{isa}) && $options{isa}->isa('Moose::Meta::TypeConstraint')) { |
60 | $options{type_constraint} = $options{isa}; |
61 | } |
62 | else { |
63 | # otherwise assume it is a constraint |
446e850f |
64 | my $constraint = Moose::Util::TypeConstraints::find_type_constraint($options{isa}); |
78cd1d3b |
65 | # if the constraing it not found .... |
66 | unless (defined $constraint) { |
67 | # assume it is a foreign class, and make |
68 | # an anon constraint for it |
69 | $constraint = Moose::Util::TypeConstraints::subtype( |
70 | 'Object', |
71 | Moose::Util::TypeConstraints::where { $_->isa($options{isa}) } |
72 | ); |
73 | } |
74 | $options{type_constraint} = $constraint; |
75 | } |
76 | } |
02a0fb52 |
77 | elsif (exists $options{does}) { |
78 | # allow for anon-subtypes here ... |
79 | if (blessed($options{does}) && $options{does}->isa('Moose::Meta::TypeConstraint')) { |
80 | $options{type_constraint} = $options{isa}; |
81 | } |
82 | else { |
83 | # otherwise assume it is a constraint |
84 | my $constraint = Moose::Util::TypeConstraints::find_type_constraint($options{does}); |
85 | # if the constraing it not found .... |
86 | unless (defined $constraint) { |
87 | # assume it is a foreign class, and make |
88 | # an anon constraint for it |
89 | $constraint = Moose::Util::TypeConstraints::subtype( |
90 | 'Role', |
91 | Moose::Util::TypeConstraints::where { $_->does($options{does}) } |
92 | ); |
93 | } |
94 | $options{type_constraint} = $constraint; |
95 | } |
96 | } |
78cd1d3b |
97 | |
4b598ea3 |
98 | if (exists $options{coerce} && $options{coerce}) { |
99 | (exists $options{type_constraint}) |
100 | || confess "You cannot have coercion without specifying a type constraint"; |
101 | confess "You cannot have a weak reference to a coerced value" |
102 | if $options{weak_ref}; |
ca01a97b |
103 | } |
78cd1d3b |
104 | |
ca01a97b |
105 | if (exists $options{lazy} && $options{lazy}) { |
106 | (exists $options{default}) |
107 | || confess "You cannot have lazy attribute without specifying a default value for it"; |
78cd1d3b |
108 | } |
109 | |
110 | $class->SUPER::new($name, %options); |
111 | } |
c0e30cf5 |
112 | |
d500266f |
113 | sub initialize_instance_slot { |
114 | my ($self, $class, $instance, $params) = @_; |
115 | my $init_arg = $self->init_arg(); |
116 | # try to fetch the init arg from the %params ... |
117 | my $val; |
118 | if (exists $params->{$init_arg}) { |
119 | $val = $params->{$init_arg}; |
120 | } |
121 | else { |
122 | # skip it if it's lazy |
123 | return if $self->is_lazy; |
124 | # and die if it's required and doesn't have a default value |
125 | confess "Attribute (" . $self->name . ") is required" |
126 | if $self->is_required && !$self->has_default; |
127 | } |
128 | # if nothing was in the %params, we can use the |
129 | # attribute's default value (if it has one) |
130 | if (!defined $val && $self->has_default) { |
131 | $val = $self->default($instance); |
132 | } |
133 | if (defined $val) { |
134 | if ($self->has_type_constraint) { |
135 | if ($self->should_coerce && $self->type_constraint->has_coercion) { |
136 | $val = $self->type_constraint->coercion->coerce($val); |
137 | } |
138 | (defined($self->type_constraint->check($val))) |
139 | || confess "Attribute (" . $self->name . ") does not pass the type contraint with '$val'"; |
140 | } |
141 | } |
142 | $instance->{$self->name} = $val; |
143 | if (defined $val && $self->is_weak_ref) { |
144 | weaken($instance->{$self->name}); |
145 | } |
146 | } |
147 | |
a15dff8d |
148 | sub generate_accessor_method { |
149 | my ($self, $attr_name) = @_; |
ca01a97b |
150 | my $value_name = $self->should_coerce ? '$val' : '$_[1]'; |
151 | my $code = 'sub { ' |
152 | . 'if (scalar(@_) == 2) {' |
153 | . ($self->is_required ? |
154 | 'defined($_[1]) || confess "Attribute ($attr_name) is required, so cannot be set to undef";' |
155 | : '') |
156 | . ($self->should_coerce ? |
157 | 'my $val = $self->type_constraint->coercion->coerce($_[1]);' |
158 | : '') |
159 | . ($self->has_type_constraint ? |
160 | ('(defined $self->type_constraint->check(' . $value_name . '))' |
161 | . '|| confess "Attribute ($attr_name) does not pass the type contraint with \'' . $value_name . '\'"' |
162 | . 'if defined ' . $value_name . ';') |
163 | : '') |
164 | . '$_[0]->{$attr_name} = ' . $value_name . ';' |
165 | . ($self->is_weak_ref ? |
166 | 'weaken($_[0]->{$attr_name});' |
167 | : '') |
8c9d74e7 |
168 | . ($self->has_trigger ? |
169 | '$self->trigger->($_[0], ' . $value_name . ');' |
170 | : '') |
ca01a97b |
171 | . ' }' |
172 | . ($self->is_lazy ? |
173 | '$_[0]->{$attr_name} = ($self->has_default ? $self->default($_[0]) : undef)' |
174 | . 'unless exists $_[0]->{$attr_name};' |
175 | : '') |
176 | . ' $_[0]->{$attr_name};' |
177 | . ' }'; |
178 | my $sub = eval $code; |
179 | confess "Could not create writer for '$attr_name' because $@ \n code: $code" if $@; |
180 | return $sub; |
a15dff8d |
181 | } |
182 | |
183 | sub generate_writer_method { |
184 | my ($self, $attr_name) = @_; |
ca01a97b |
185 | my $value_name = $self->should_coerce ? '$val' : '$_[1]'; |
186 | my $code = 'sub { ' |
187 | . ($self->is_required ? |
188 | 'defined($_[1]) || confess "Attribute ($attr_name) is required, so cannot be set to undef";' |
189 | : '') |
190 | . ($self->should_coerce ? |
191 | 'my $val = $self->type_constraint->coercion->coerce($_[1]);' |
192 | : '') |
193 | . ($self->has_type_constraint ? |
194 | ('(defined $self->type_constraint->check(' . $value_name . '))' |
195 | . '|| confess "Attribute ($attr_name) does not pass the type contraint with \'' . $value_name . '\'"' |
196 | . 'if defined ' . $value_name . ';') |
197 | : '') |
198 | . '$_[0]->{$attr_name} = ' . $value_name . ';' |
199 | . ($self->is_weak_ref ? |
200 | 'weaken($_[0]->{$attr_name});' |
201 | : '') |
8c9d74e7 |
202 | . ($self->has_trigger ? |
203 | '$self->trigger->($_[0], ' . $value_name . ');' |
204 | : '') |
ca01a97b |
205 | . ' }'; |
206 | my $sub = eval $code; |
207 | confess "Could not create writer for '$attr_name' because $@ \n code: $code" if $@; |
208 | return $sub; |
a15dff8d |
209 | } |
c0e30cf5 |
210 | |
d7f17ebb |
211 | sub generate_reader_method { |
212 | my ($self, $attr_name) = @_; |
ca01a97b |
213 | my $code = 'sub {' |
214 | . 'confess "Cannot assign a value to a read-only accessor" if @_ > 1;' |
215 | . ($self->is_lazy ? |
216 | '$_[0]->{$attr_name} = ($self->has_default ? $self->default($_[0]) : undef)' |
217 | . 'unless exists $_[0]->{$attr_name};' |
218 | : '') |
219 | . '$_[0]->{$attr_name};' |
220 | . '}'; |
221 | my $sub = eval $code; |
222 | confess "Could not create reader for '$attr_name' because $@ \n code: $code" if $@; |
223 | return $sub; |
d7f17ebb |
224 | } |
225 | |
c0e30cf5 |
226 | 1; |
227 | |
228 | __END__ |
229 | |
230 | =pod |
231 | |
232 | =head1 NAME |
233 | |
6ba6d68c |
234 | Moose::Meta::Attribute - The Moose attribute metaclass |
c0e30cf5 |
235 | |
236 | =head1 DESCRIPTION |
237 | |
e522431d |
238 | This is a subclass of L<Class::MOP::Attribute> with Moose specific |
6ba6d68c |
239 | extensions. |
240 | |
241 | For the most part, the only time you will ever encounter an |
242 | instance of this class is if you are doing some serious deep |
243 | introspection. To really understand this class, you need to refer |
244 | to the L<Class::MOP::Attribute> documentation. |
e522431d |
245 | |
c0e30cf5 |
246 | =head1 METHODS |
247 | |
6ba6d68c |
248 | =head2 Overridden methods |
249 | |
250 | These methods override methods in L<Class::MOP::Attribute> and add |
251 | Moose specific features. You can safely assume though that they |
252 | will behave just as L<Class::MOP::Attribute> does. |
253 | |
c0e30cf5 |
254 | =over 4 |
255 | |
256 | =item B<new> |
257 | |
d500266f |
258 | =item B<initialize_instance_slot> |
259 | |
a15dff8d |
260 | =item B<generate_accessor_method> |
261 | |
262 | =item B<generate_writer_method> |
263 | |
d7f17ebb |
264 | =item B<generate_reader_method> |
265 | |
a15dff8d |
266 | =back |
267 | |
6ba6d68c |
268 | =head2 Additional Moose features |
269 | |
270 | Moose attributes support type-contstraint checking, weak reference |
271 | creation and type coercion. |
272 | |
a15dff8d |
273 | =over 4 |
274 | |
275 | =item B<has_type_constraint> |
276 | |
6ba6d68c |
277 | Returns true if this meta-attribute has a type constraint. |
278 | |
a15dff8d |
279 | =item B<type_constraint> |
280 | |
6ba6d68c |
281 | A read-only accessor for this meta-attribute's type constraint. For |
282 | more information on what you can do with this, see the documentation |
283 | for L<Moose::Meta::TypeConstraint>. |
a15dff8d |
284 | |
6ba6d68c |
285 | =item B<is_weak_ref> |
a15dff8d |
286 | |
02a0fb52 |
287 | Returns true if this meta-attribute produces a weak reference. |
4b598ea3 |
288 | |
ca01a97b |
289 | =item B<is_required> |
290 | |
02a0fb52 |
291 | Returns true if this meta-attribute is required to have a value. |
ca01a97b |
292 | |
293 | =item B<is_lazy> |
294 | |
02a0fb52 |
295 | Returns true if this meta-attribute should be initialized lazily. |
ca01a97b |
296 | |
297 | NOTE: lazy attributes, B<must> have a C<default> field set. |
298 | |
34a66aa3 |
299 | =item B<should_coerce> |
4b598ea3 |
300 | |
02a0fb52 |
301 | Returns true if this meta-attribute should perform type coercion. |
6ba6d68c |
302 | |
8c9d74e7 |
303 | =item B<has_trigger> |
304 | |
02a0fb52 |
305 | Returns true if this meta-attribute has a trigger set. |
306 | |
8c9d74e7 |
307 | =item B<trigger> |
308 | |
02a0fb52 |
309 | This is a CODE reference which will be executed every time the |
310 | value of an attribute is assigned. The CODE ref will get two values, |
311 | the invocant and the new value. This can be used to handle I<basic> |
312 | bi-directional relations. |
313 | |
c0e30cf5 |
314 | =back |
315 | |
316 | =head1 BUGS |
317 | |
318 | All complex software has bugs lurking in it, and this module is no |
319 | exception. If you find a bug please either email me, or add the bug |
320 | to cpan-RT. |
321 | |
c0e30cf5 |
322 | =head1 AUTHOR |
323 | |
324 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
325 | |
326 | =head1 COPYRIGHT AND LICENSE |
327 | |
328 | Copyright 2006 by Infinity Interactive, Inc. |
329 | |
330 | L<http://www.iinteractive.com> |
331 | |
332 | This library is free software; you can redistribute it and/or modify |
333 | it under the same terms as Perl itself. |
334 | |
335 | =cut |