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1 | #!/usr/bin/env perl |
2 | package Mouse::Attribute; |
3 | use strict; |
4 | use warnings; |
5 | |
6 | use Carp 'confess'; |
7 | |
8 | sub new { |
9 | my $class = shift; |
10 | my %args = @_; |
11 | |
7ee01d77 |
12 | $args{init_arg} = $args{name} |
13 | unless exists $args{init_arg}; |
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14 | $args{is} ||= ''; |
15 | |
16 | bless \%args, $class; |
17 | } |
18 | |
186657a9 |
19 | sub name { $_[0]->{name} } |
20 | sub class { $_[0]->{class} } |
21 | sub default { $_[0]->{default} } |
22 | sub predicate { $_[0]->{predicate} } |
23 | sub clearer { $_[0]->{clearer} } |
24 | sub handles { $_[0]->{handles} } |
25 | sub weak_ref { $_[0]->{weak_ref} } |
26 | sub init_arg { $_[0]->{init_arg} } |
27 | sub type_constraint { $_[0]->{type_constraint} } |
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28 | |
29 | sub generate_accessor { |
30 | my $attribute = shift; |
31 | |
32 | my $key = $attribute->{init_arg}; |
33 | my $default = $attribute->{default}; |
34 | my $trigger = $attribute->{trigger}; |
35 | |
36 | my $accessor = 'sub { |
37 | my $self = shift;'; |
38 | |
39 | if ($attribute->{is} eq 'rw') { |
40 | $accessor .= 'if (@_) { |
41 | $self->{$key} = $_[0];'; |
42 | |
43 | if ($attribute->{weak_ref}) { |
44 | $accessor .= 'Scalar::Util::weaken($self->{$key});'; |
45 | } |
46 | |
47 | if ($trigger) { |
48 | $accessor .= '$trigger->($self, $_[0], $attribute);'; |
49 | } |
50 | |
51 | $accessor .= '}'; |
52 | } |
53 | else { |
54 | } |
55 | |
56 | if ($attribute->{lazy}) { |
57 | $accessor .= '$self->{$key} = '; |
58 | $accessor .= ref($attribute->{default}) eq 'CODE' |
59 | ? '$default->($self)' |
60 | : '$default'; |
61 | $accessor .= ' if !exists($self->{$key});'; |
62 | } |
63 | |
64 | $accessor .= 'return $self->{$key} |
65 | }'; |
66 | |
67 | return eval $accessor; |
68 | } |
69 | |
70 | sub generate_predicate { |
71 | my $attribute = shift; |
72 | my $key = $attribute->{init_arg}; |
73 | |
74 | my $predicate = 'sub { exists($_[0]->{$key}) }'; |
75 | |
76 | return eval $predicate; |
77 | } |
78 | |
79 | sub generate_clearer { |
80 | my $attribute = shift; |
81 | my $key = $attribute->{init_arg}; |
82 | |
83 | my $predicate = 'sub { delete($_[0]->{$key}) }'; |
84 | |
85 | return eval $predicate; |
86 | } |
87 | |
88 | sub generate_handles { |
89 | my $attribute = shift; |
90 | my $reader = $attribute->{name}; |
91 | |
92 | my %method_map; |
93 | |
94 | for my $local_method (keys %{ $attribute->{handles} }) { |
95 | my $remote_method = $attribute->{handles}{$local_method}; |
96 | |
97 | my $method = 'sub { |
98 | my $self = shift; |
99 | $self->$reader->$remote_method(@_) |
100 | }'; |
101 | |
102 | $method_map{$local_method} = eval $method; |
103 | } |
104 | |
105 | return \%method_map; |
106 | } |
107 | |
108 | sub create { |
109 | my ($self, $class, $name, %args) = @_; |
110 | |
111 | confess "You must specify a default for lazy attribute '$name'" |
112 | if $args{lazy} && !exists($args{default}); |
113 | |
114 | confess "Trigger is not allowed on read-only attribute '$name'" |
115 | if $args{trigger} && $args{is} ne 'rw'; |
116 | |
117 | confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])" |
118 | if ref($args{default}) |
119 | && ref($args{default}) ne 'CODE'; |
120 | |
121 | $args{handles} = { map { $_ => $_ } @{ $args{handles} } } |
122 | if $args{handles} |
123 | && ref($args{handles}) eq 'ARRAY'; |
124 | |
125 | confess "You must pass a HASH or ARRAY to handles" |
126 | if exists($args{handles}) |
127 | && ref($args{handles}) ne 'HASH'; |
128 | |
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129 | $args{type_constraint} = delete $args{isa}; |
130 | |
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131 | my $attribute = $self->new(%args, name => $name, class => $class); |
132 | my $meta = $class->meta; |
133 | |
b2500191 |
134 | $meta->add_attribute($attribute); |
135 | |
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136 | # install an accessor |
137 | if ($attribute->{is} eq 'rw' || $attribute->{is} eq 'ro') { |
138 | my $accessor = $attribute->generate_accessor; |
139 | no strict 'refs'; |
140 | *{ $class . '::' . $name } = $accessor; |
141 | } |
142 | |
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143 | for my $method (qw/predicate clearer/) { |
144 | if (exists $attribute->{$method}) { |
145 | my $generator = "generate_$method"; |
146 | my $coderef = $attribute->$generator; |
147 | no strict 'refs'; |
148 | *{ $class . '::' . $attribute->{$method} } = $coderef; |
149 | } |
150 | } |
151 | |
152 | if ($attribute->{handles}) { |
153 | my $method_map = $attribute->generate_handles; |
154 | for my $method_name (keys %$method_map) { |
155 | no strict 'refs'; |
156 | *{ $class . '::' . $method_name } = $method_map->{$method_name}; |
157 | } |
158 | } |
159 | |
160 | return $attribute; |
161 | } |
162 | |
163 | 1; |
164 | |
165 | __END__ |
166 | |
167 | =head1 NAME |
168 | |
169 | Mouse::Attribute - attribute metaclass |
170 | |
171 | =head1 METHODS |
172 | |
173 | =head2 new %args -> Mouse::Attribute |
174 | |
175 | Instantiates a new Mouse::Attribute. Does nothing else. |
176 | |
177 | =head2 create OwnerClass, AttributeName, %args -> Mouse::Attribute |
178 | |
179 | Creates a new attribute in OwnerClass. Accessors and helper methods are |
180 | installed. Some error checking is done. |
181 | |
182 | =head2 name -> AttributeName |
183 | |
184 | =head2 class -> OwnerClass |
185 | |
186 | =head2 default -> Value |
187 | |
188 | =head2 predicate -> MethodName |
189 | |
190 | =head2 clearer -> MethodName |
191 | |
192 | =head2 handles -> { LocalName => RemoteName } |
193 | |
194 | =head2 weak_ref -> Bool |
195 | |
196 | =head2 init_arg -> Str |
197 | |
198 | Informational methods. |
199 | |
200 | =head2 generate_accessor -> CODE |
201 | |
202 | Creates a new code reference for the attribute's accessor. |
203 | |
204 | =head2 generate_predicate -> CODE |
205 | |
206 | Creates a new code reference for the attribute's predicate. |
207 | |
208 | =head2 generate_clearer -> CODE |
209 | |
210 | Creates a new code reference for the attribute's clearer. |
211 | |
212 | =head2 generate_handles -> { MethodName => CODE } |
213 | |
214 | Creates a new code reference for each of the attribute's handles methods. |
215 | |
216 | =cut |
217 | |