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 | |
8c9d74e7 |
10 | our $VERSION = '0.04'; |
78cd1d3b |
11 | |
a3c7e2fe |
12 | use Moose::Util::TypeConstraints (); |
bc1e29b5 |
13 | |
c0e30cf5 |
14 | use base 'Class::MOP::Attribute'; |
15 | |
ca01a97b |
16 | __PACKAGE__->meta->add_attribute('required' => (reader => 'is_required' )); |
17 | __PACKAGE__->meta->add_attribute('lazy' => (reader => 'is_lazy' )); |
6ba6d68c |
18 | __PACKAGE__->meta->add_attribute('coerce' => (reader => 'should_coerce')); |
19 | __PACKAGE__->meta->add_attribute('weak_ref' => (reader => 'is_weak_ref' )); |
82168dbb |
20 | __PACKAGE__->meta->add_attribute('type_constraint' => ( |
21 | reader => 'type_constraint', |
22 | predicate => 'has_type_constraint', |
23 | )); |
8c9d74e7 |
24 | __PACKAGE__->meta->add_attribute('trigger' => ( |
25 | reader => 'trigger', |
26 | predicate => 'has_trigger', |
27 | )); |
82168dbb |
28 | |
78cd1d3b |
29 | sub new { |
30 | my ($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} = $name; |
8c9d74e7 |
40 | (reftype($options{trigger}) eq 'CODE') |
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($options{does})) |
51 | || confess "Cannot have an isa option and a does option if the isa does not do the does"; |
52 | } |
53 | } |
54 | |
78cd1d3b |
55 | # allow for anon-subtypes here ... |
56 | if (blessed($options{isa}) && $options{isa}->isa('Moose::Meta::TypeConstraint')) { |
57 | $options{type_constraint} = $options{isa}; |
58 | } |
59 | else { |
60 | # otherwise assume it is a constraint |
446e850f |
61 | my $constraint = Moose::Util::TypeConstraints::find_type_constraint($options{isa}); |
78cd1d3b |
62 | # if the constraing it not found .... |
63 | unless (defined $constraint) { |
64 | # assume it is a foreign class, and make |
65 | # an anon constraint for it |
66 | $constraint = Moose::Util::TypeConstraints::subtype( |
67 | 'Object', |
68 | Moose::Util::TypeConstraints::where { $_->isa($options{isa}) } |
69 | ); |
70 | } |
71 | $options{type_constraint} = $constraint; |
72 | } |
73 | } |
02a0fb52 |
74 | elsif (exists $options{does}) { |
75 | # allow for anon-subtypes here ... |
76 | if (blessed($options{does}) && $options{does}->isa('Moose::Meta::TypeConstraint')) { |
77 | $options{type_constraint} = $options{isa}; |
78 | } |
79 | else { |
80 | # otherwise assume it is a constraint |
81 | my $constraint = Moose::Util::TypeConstraints::find_type_constraint($options{does}); |
82 | # if the constraing it not found .... |
83 | unless (defined $constraint) { |
84 | # assume it is a foreign class, and make |
85 | # an anon constraint for it |
86 | $constraint = Moose::Util::TypeConstraints::subtype( |
87 | 'Role', |
88 | Moose::Util::TypeConstraints::where { $_->does($options{does}) } |
89 | ); |
90 | } |
91 | $options{type_constraint} = $constraint; |
92 | } |
93 | } |
78cd1d3b |
94 | |
4b598ea3 |
95 | if (exists $options{coerce} && $options{coerce}) { |
96 | (exists $options{type_constraint}) |
97 | || confess "You cannot have coercion without specifying a type constraint"; |
98 | confess "You cannot have a weak reference to a coerced value" |
99 | if $options{weak_ref}; |
ca01a97b |
100 | } |
78cd1d3b |
101 | |
ca01a97b |
102 | if (exists $options{lazy} && $options{lazy}) { |
103 | (exists $options{default}) |
104 | || confess "You cannot have lazy attribute without specifying a default value for it"; |
78cd1d3b |
105 | } |
106 | |
107 | $class->SUPER::new($name, %options); |
108 | } |
c0e30cf5 |
109 | |
a15dff8d |
110 | sub generate_accessor_method { |
111 | my ($self, $attr_name) = @_; |
ca01a97b |
112 | my $value_name = $self->should_coerce ? '$val' : '$_[1]'; |
113 | my $code = 'sub { ' |
114 | . 'if (scalar(@_) == 2) {' |
115 | . ($self->is_required ? |
116 | 'defined($_[1]) || confess "Attribute ($attr_name) is required, so cannot be set to undef";' |
117 | : '') |
118 | . ($self->should_coerce ? |
119 | 'my $val = $self->type_constraint->coercion->coerce($_[1]);' |
120 | : '') |
121 | . ($self->has_type_constraint ? |
122 | ('(defined $self->type_constraint->check(' . $value_name . '))' |
123 | . '|| confess "Attribute ($attr_name) does not pass the type contraint with \'' . $value_name . '\'"' |
124 | . 'if defined ' . $value_name . ';') |
125 | : '') |
126 | . '$_[0]->{$attr_name} = ' . $value_name . ';' |
127 | . ($self->is_weak_ref ? |
128 | 'weaken($_[0]->{$attr_name});' |
129 | : '') |
8c9d74e7 |
130 | . ($self->has_trigger ? |
131 | '$self->trigger->($_[0], ' . $value_name . ');' |
132 | : '') |
ca01a97b |
133 | . ' }' |
134 | . ($self->is_lazy ? |
135 | '$_[0]->{$attr_name} = ($self->has_default ? $self->default($_[0]) : undef)' |
136 | . 'unless exists $_[0]->{$attr_name};' |
137 | : '') |
138 | . ' $_[0]->{$attr_name};' |
139 | . ' }'; |
140 | my $sub = eval $code; |
141 | confess "Could not create writer for '$attr_name' because $@ \n code: $code" if $@; |
142 | return $sub; |
a15dff8d |
143 | } |
144 | |
145 | sub generate_writer_method { |
146 | my ($self, $attr_name) = @_; |
ca01a97b |
147 | my $value_name = $self->should_coerce ? '$val' : '$_[1]'; |
148 | my $code = 'sub { ' |
149 | . ($self->is_required ? |
150 | 'defined($_[1]) || confess "Attribute ($attr_name) is required, so cannot be set to undef";' |
151 | : '') |
152 | . ($self->should_coerce ? |
153 | 'my $val = $self->type_constraint->coercion->coerce($_[1]);' |
154 | : '') |
155 | . ($self->has_type_constraint ? |
156 | ('(defined $self->type_constraint->check(' . $value_name . '))' |
157 | . '|| confess "Attribute ($attr_name) does not pass the type contraint with \'' . $value_name . '\'"' |
158 | . 'if defined ' . $value_name . ';') |
159 | : '') |
160 | . '$_[0]->{$attr_name} = ' . $value_name . ';' |
161 | . ($self->is_weak_ref ? |
162 | 'weaken($_[0]->{$attr_name});' |
163 | : '') |
8c9d74e7 |
164 | . ($self->has_trigger ? |
165 | '$self->trigger->($_[0], ' . $value_name . ');' |
166 | : '') |
ca01a97b |
167 | . ' }'; |
168 | my $sub = eval $code; |
169 | confess "Could not create writer for '$attr_name' because $@ \n code: $code" if $@; |
170 | return $sub; |
a15dff8d |
171 | } |
c0e30cf5 |
172 | |
d7f17ebb |
173 | sub generate_reader_method { |
174 | my ($self, $attr_name) = @_; |
ca01a97b |
175 | my $code = 'sub {' |
176 | . 'confess "Cannot assign a value to a read-only accessor" if @_ > 1;' |
177 | . ($self->is_lazy ? |
178 | '$_[0]->{$attr_name} = ($self->has_default ? $self->default($_[0]) : undef)' |
179 | . 'unless exists $_[0]->{$attr_name};' |
180 | : '') |
181 | . '$_[0]->{$attr_name};' |
182 | . '}'; |
183 | my $sub = eval $code; |
184 | confess "Could not create reader for '$attr_name' because $@ \n code: $code" if $@; |
185 | return $sub; |
d7f17ebb |
186 | } |
187 | |
c0e30cf5 |
188 | 1; |
189 | |
190 | __END__ |
191 | |
192 | =pod |
193 | |
194 | =head1 NAME |
195 | |
6ba6d68c |
196 | Moose::Meta::Attribute - The Moose attribute metaclass |
c0e30cf5 |
197 | |
198 | =head1 DESCRIPTION |
199 | |
e522431d |
200 | This is a subclass of L<Class::MOP::Attribute> with Moose specific |
6ba6d68c |
201 | extensions. |
202 | |
203 | For the most part, the only time you will ever encounter an |
204 | instance of this class is if you are doing some serious deep |
205 | introspection. To really understand this class, you need to refer |
206 | to the L<Class::MOP::Attribute> documentation. |
e522431d |
207 | |
c0e30cf5 |
208 | =head1 METHODS |
209 | |
6ba6d68c |
210 | =head2 Overridden methods |
211 | |
212 | These methods override methods in L<Class::MOP::Attribute> and add |
213 | Moose specific features. You can safely assume though that they |
214 | will behave just as L<Class::MOP::Attribute> does. |
215 | |
c0e30cf5 |
216 | =over 4 |
217 | |
218 | =item B<new> |
219 | |
a15dff8d |
220 | =item B<generate_accessor_method> |
221 | |
222 | =item B<generate_writer_method> |
223 | |
d7f17ebb |
224 | =item B<generate_reader_method> |
225 | |
a15dff8d |
226 | =back |
227 | |
6ba6d68c |
228 | =head2 Additional Moose features |
229 | |
230 | Moose attributes support type-contstraint checking, weak reference |
231 | creation and type coercion. |
232 | |
a15dff8d |
233 | =over 4 |
234 | |
235 | =item B<has_type_constraint> |
236 | |
6ba6d68c |
237 | Returns true if this meta-attribute has a type constraint. |
238 | |
a15dff8d |
239 | =item B<type_constraint> |
240 | |
6ba6d68c |
241 | A read-only accessor for this meta-attribute's type constraint. For |
242 | more information on what you can do with this, see the documentation |
243 | for L<Moose::Meta::TypeConstraint>. |
a15dff8d |
244 | |
6ba6d68c |
245 | =item B<is_weak_ref> |
a15dff8d |
246 | |
02a0fb52 |
247 | Returns true if this meta-attribute produces a weak reference. |
4b598ea3 |
248 | |
ca01a97b |
249 | =item B<is_required> |
250 | |
02a0fb52 |
251 | Returns true if this meta-attribute is required to have a value. |
ca01a97b |
252 | |
253 | =item B<is_lazy> |
254 | |
02a0fb52 |
255 | Returns true if this meta-attribute should be initialized lazily. |
ca01a97b |
256 | |
257 | NOTE: lazy attributes, B<must> have a C<default> field set. |
258 | |
34a66aa3 |
259 | =item B<should_coerce> |
4b598ea3 |
260 | |
02a0fb52 |
261 | Returns true if this meta-attribute should perform type coercion. |
6ba6d68c |
262 | |
8c9d74e7 |
263 | =item B<has_trigger> |
264 | |
02a0fb52 |
265 | Returns true if this meta-attribute has a trigger set. |
266 | |
8c9d74e7 |
267 | =item B<trigger> |
268 | |
02a0fb52 |
269 | This is a CODE reference which will be executed every time the |
270 | value of an attribute is assigned. The CODE ref will get two values, |
271 | the invocant and the new value. This can be used to handle I<basic> |
272 | bi-directional relations. |
273 | |
c0e30cf5 |
274 | =back |
275 | |
276 | =head1 BUGS |
277 | |
278 | All complex software has bugs lurking in it, and this module is no |
279 | exception. If you find a bug please either email me, or add the bug |
280 | to cpan-RT. |
281 | |
c0e30cf5 |
282 | =head1 AUTHOR |
283 | |
284 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
285 | |
286 | =head1 COPYRIGHT AND LICENSE |
287 | |
288 | Copyright 2006 by Infinity Interactive, Inc. |
289 | |
290 | L<http://www.iinteractive.com> |
291 | |
292 | This library is free software; you can redistribute it and/or modify |
293 | it under the same terms as Perl itself. |
294 | |
295 | =cut |