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