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c3398f5b |
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}; |
c3398f5b |
14 | $args{is} ||= ''; |
15 | |
16 | bless \%args, $class; |
17 | } |
18 | |
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 | |
28 | sub generate_accessor { |
29 | my $attribute = shift; |
30 | |
31 | my $key = $attribute->{init_arg}; |
32 | my $default = $attribute->{default}; |
33 | my $trigger = $attribute->{trigger}; |
34 | |
35 | my $accessor = 'sub { |
36 | my $self = shift;'; |
37 | |
38 | if ($attribute->{is} eq 'rw') { |
39 | $accessor .= 'if (@_) { |
40 | $self->{$key} = $_[0];'; |
41 | |
42 | if ($attribute->{weak_ref}) { |
43 | $accessor .= 'Scalar::Util::weaken($self->{$key});'; |
44 | } |
45 | |
46 | if ($trigger) { |
47 | $accessor .= '$trigger->($self, $_[0], $attribute);'; |
48 | } |
49 | |
50 | $accessor .= '}'; |
51 | } |
52 | else { |
53 | } |
54 | |
55 | if ($attribute->{lazy}) { |
56 | $accessor .= '$self->{$key} = '; |
57 | $accessor .= ref($attribute->{default}) eq 'CODE' |
58 | ? '$default->($self)' |
59 | : '$default'; |
60 | $accessor .= ' if !exists($self->{$key});'; |
61 | } |
62 | |
63 | $accessor .= 'return $self->{$key} |
64 | }'; |
65 | |
66 | return eval $accessor; |
67 | } |
68 | |
69 | sub generate_predicate { |
70 | my $attribute = shift; |
71 | my $key = $attribute->{init_arg}; |
72 | |
73 | my $predicate = 'sub { exists($_[0]->{$key}) }'; |
74 | |
75 | return eval $predicate; |
76 | } |
77 | |
78 | sub generate_clearer { |
79 | my $attribute = shift; |
80 | my $key = $attribute->{init_arg}; |
81 | |
82 | my $predicate = 'sub { delete($_[0]->{$key}) }'; |
83 | |
84 | return eval $predicate; |
85 | } |
86 | |
87 | sub generate_handles { |
88 | my $attribute = shift; |
89 | my $reader = $attribute->{name}; |
90 | |
91 | my %method_map; |
92 | |
93 | for my $local_method (keys %{ $attribute->{handles} }) { |
94 | my $remote_method = $attribute->{handles}{$local_method}; |
95 | |
96 | my $method = 'sub { |
97 | my $self = shift; |
98 | $self->$reader->$remote_method(@_) |
99 | }'; |
100 | |
101 | $method_map{$local_method} = eval $method; |
102 | } |
103 | |
104 | return \%method_map; |
105 | } |
106 | |
107 | sub create { |
108 | my ($self, $class, $name, %args) = @_; |
109 | |
110 | confess "You must specify a default for lazy attribute '$name'" |
111 | if $args{lazy} && !exists($args{default}); |
112 | |
113 | confess "Trigger is not allowed on read-only attribute '$name'" |
114 | if $args{trigger} && $args{is} ne 'rw'; |
115 | |
116 | confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])" |
117 | if ref($args{default}) |
118 | && ref($args{default}) ne 'CODE'; |
119 | |
120 | $args{handles} = { map { $_ => $_ } @{ $args{handles} } } |
121 | if $args{handles} |
122 | && ref($args{handles}) eq 'ARRAY'; |
123 | |
124 | confess "You must pass a HASH or ARRAY to handles" |
125 | if exists($args{handles}) |
126 | && ref($args{handles}) ne 'HASH'; |
127 | |
128 | my $attribute = $self->new(%args, name => $name, class => $class); |
129 | my $meta = $class->meta; |
130 | |
b2500191 |
131 | $meta->add_attribute($attribute); |
132 | |
c3398f5b |
133 | # install an accessor |
134 | if ($attribute->{is} eq 'rw' || $attribute->{is} eq 'ro') { |
135 | my $accessor = $attribute->generate_accessor; |
136 | no strict 'refs'; |
137 | *{ $class . '::' . $name } = $accessor; |
138 | } |
139 | |
c3398f5b |
140 | for my $method (qw/predicate clearer/) { |
141 | if (exists $attribute->{$method}) { |
142 | my $generator = "generate_$method"; |
143 | my $coderef = $attribute->$generator; |
144 | no strict 'refs'; |
145 | *{ $class . '::' . $attribute->{$method} } = $coderef; |
146 | } |
147 | } |
148 | |
149 | if ($attribute->{handles}) { |
150 | my $method_map = $attribute->generate_handles; |
151 | for my $method_name (keys %$method_map) { |
152 | no strict 'refs'; |
153 | *{ $class . '::' . $method_name } = $method_map->{$method_name}; |
154 | } |
155 | } |
156 | |
157 | return $attribute; |
158 | } |
159 | |
160 | 1; |
161 | |
162 | __END__ |
163 | |
164 | =head1 NAME |
165 | |
166 | Mouse::Attribute - attribute metaclass |
167 | |
168 | =head1 METHODS |
169 | |
170 | =head2 new %args -> Mouse::Attribute |
171 | |
172 | Instantiates a new Mouse::Attribute. Does nothing else. |
173 | |
174 | =head2 create OwnerClass, AttributeName, %args -> Mouse::Attribute |
175 | |
176 | Creates a new attribute in OwnerClass. Accessors and helper methods are |
177 | installed. Some error checking is done. |
178 | |
179 | =head2 name -> AttributeName |
180 | |
181 | =head2 class -> OwnerClass |
182 | |
183 | =head2 default -> Value |
184 | |
185 | =head2 predicate -> MethodName |
186 | |
187 | =head2 clearer -> MethodName |
188 | |
189 | =head2 handles -> { LocalName => RemoteName } |
190 | |
191 | =head2 weak_ref -> Bool |
192 | |
193 | =head2 init_arg -> Str |
194 | |
195 | Informational methods. |
196 | |
197 | =head2 generate_accessor -> CODE |
198 | |
199 | Creates a new code reference for the attribute's accessor. |
200 | |
201 | =head2 generate_predicate -> CODE |
202 | |
203 | Creates a new code reference for the attribute's predicate. |
204 | |
205 | =head2 generate_clearer -> CODE |
206 | |
207 | Creates a new code reference for the attribute's clearer. |
208 | |
209 | =head2 generate_handles -> { MethodName => CODE } |
210 | |
211 | Creates a new code reference for each of the attribute's handles methods. |
212 | |
213 | =cut |
214 | |