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857f87a7 |
1 | |
2 | package Class::MOP::Class::Immutable; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
7 | use Carp 'confess'; |
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8 | use Scalar::Util 'blessed', 'looks_like_number'; |
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9 | |
10 | our $VERSION = '0.01'; |
11 | |
12 | use base 'Class::MOP::Class'; |
13 | |
14 | # methods which can *not* be called |
15 | |
16 | sub reinitialize { confess 'Cannot call method "reinitialize" on an immutable instance' } |
17 | |
18 | sub add_method { confess 'Cannot call method "add_method" on an immutable instance' } |
19 | sub alias_method { confess 'Cannot call method "alias_method" on an immutable instance' } |
20 | sub remove_method { confess 'Cannot call method "remove_method" on an immutable instance' } |
21 | |
22 | sub add_attribute { confess 'Cannot call method "add_attribute" on an immutable instance' } |
23 | sub remove_attribute { confess 'Cannot call method "remove_attribute" on an immutable instance' } |
24 | |
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25 | sub add_package_symbol { confess 'Cannot call method "add_package_symbol" on an immutable instance' } |
26 | sub remove_package_symbol { confess 'Cannot call method "remove_package_symbol" on an immutable instance' } |
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27 | |
28 | # NOTE: |
29 | # superclasses is an accessor, so |
30 | # it just cannot be changed |
31 | sub superclasses { |
32 | my $class = shift; |
33 | (!@_) || confess 'Cannot change the "superclasses" on an immmutable instance'; |
34 | no strict 'refs'; |
35 | @{$class->name . '::ISA'}; |
36 | } |
37 | |
38 | # predicates |
39 | |
40 | sub is_mutable { 0 } |
41 | sub is_immutable { 1 } |
42 | |
43 | sub make_immutable { () } |
44 | |
45 | sub make_metaclass_immutable { |
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46 | my ($class, $metaclass, %options) = @_; |
47 | |
48 | $options{inline_accessors} ||= 1; |
49 | $options{inline_constructor} ||= 1; |
50 | $options{constructor_name} ||= 'new'; |
51 | |
52 | my $meta_instance = $metaclass->get_meta_instance; |
53 | $metaclass->{'___class_precedence_list'} = [ $metaclass->class_precedence_list ]; |
54 | $metaclass->{'___compute_all_applicable_attributes'} = [ $metaclass->compute_all_applicable_attributes ]; |
55 | $metaclass->{'___get_meta_instance'} = $meta_instance; |
56 | $metaclass->{'___original_class'} = blessed($metaclass); |
57 | |
58 | if ($options{inline_accessors}) { |
59 | foreach my $attr_name ($metaclass->get_attribute_list) { |
60 | my $attr = $metaclass->get_attribute($attr_name); |
61 | $attr->install_accessors(1); # inline the accessors |
62 | } |
63 | } |
64 | |
65 | if ($options{inline_constructor}) { |
66 | $metaclass->add_method( |
67 | $options{constructor_name}, |
68 | $class->_generate_inline_constructor( |
69 | \%options, |
70 | $meta_instance, |
71 | $metaclass->{'___compute_all_applicable_attributes'} |
72 | ) |
73 | ); |
74 | } |
75 | |
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76 | bless $metaclass => $class; |
77 | } |
78 | |
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79 | sub _generate_inline_constructor { |
80 | my ($class, $options, $meta_instance, $attrs) = @_; |
81 | # TODO: |
82 | # the %options should also include a both |
83 | # a call 'initializer' and call 'SUPER::' |
84 | # options, which should cover approx 90% |
85 | # of the possible use cases (even if it |
86 | # requires some adaption on the part of |
87 | # the author, after all, nothing is free) |
88 | my $source = 'sub {'; |
89 | $source .= "\n" . 'my ($class, %params) = @_;'; |
90 | $source .= "\n" . 'my $instance = ' . $meta_instance->inline_create_instance('$class'); |
91 | $source .= ";\n" . (join ";\n" => map { |
92 | $class->_generate_slot_initializer($meta_instance, $attrs, $_) |
93 | } 0 .. (@$attrs - 1)); |
94 | $source .= ";\n" . 'return $instance'; |
95 | $source .= ";\n" . '}'; |
495af518 |
96 | warn $source if $options->{debug}; |
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97 | my $code = eval $source; |
98 | confess "Could not eval the constructor :\n\n$source\n\nbecause :\n\n$@" if $@; |
99 | return $code; |
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100 | } |
101 | |
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102 | sub _generate_slot_initializer { |
103 | my ($class, $meta_instance, $attrs, $index) = @_; |
104 | my $attr = $attrs->[$index]; |
105 | my $default; |
106 | if ($attr->has_default) { |
107 | if ($attr->is_default_a_coderef) { |
108 | $default = '$attrs->[' . $index . ']->default($instance)'; |
109 | } |
110 | else { |
111 | $default = $attrs->[$index]->default; |
112 | unless (looks_like_number($default)) { |
113 | $default = "'$default'"; |
114 | } |
115 | # TODO: |
116 | # we should use Data::Dumper to |
117 | # output any ref's here, obviously |
118 | # we cannot handle Scalar refs, but |
119 | # it should work for Array and Hash |
120 | # refs pretty well. |
121 | } |
122 | } |
123 | $meta_instance->inline_set_slot_value( |
124 | '$instance', |
125 | $attr->name, |
126 | ('$params{\'' . $attr->init_arg . '\'}' . (defined $default ? (' || ' . $default) : '')) |
127 | ) |
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128 | } |
129 | |
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130 | # cached methods |
131 | |
132 | sub get_meta_instance { (shift)->{'___get_meta_instance'} } |
133 | sub class_precedence_list { @{(shift)->{'___class_precedence_list'}} } |
134 | sub compute_all_applicable_attributes { @{(shift)->{'___compute_all_applicable_attributes'}} } |
135 | |
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136 | 1; |
137 | |
138 | __END__ |
139 | |
140 | =pod |
141 | |
142 | =head1 NAME |
143 | |
144 | Class::MOP::Class::Immutable - An immutable version of Class::MOP::Class |
145 | |
146 | =head1 SYNOPSIS |
147 | |
148 | =head1 DESCRIPTION |
149 | |
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150 | Class::MOP offers many benefits to object oriented development but it |
151 | comes at a cost. Pure Class::MOP classes can be quite a bit slower than |
152 | the typical hand coded Perl classes. This is because just about |
153 | I<everything> is recalculated on the fly, and nothing is cached. The |
154 | reason this is so, is because Perl itself allows you to modify virtually |
155 | everything at runtime. Class::MOP::Class::Immutable offers an alternative |
156 | to this. |
157 | |
158 | By making your class immutable, you are promising that you will not |
159 | modify your inheritence tree or the attributes of any classes in |
160 | that tree. Since runtime modifications like this are fairly atypical |
161 | (and usually recomended against), this is not usally a very hard promise |
162 | to make. For making this promise you are given a wide range of |
163 | optimization options which bring speed close to (and sometimes above) |
164 | those of typical hand coded Perl. |
165 | |
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166 | =head1 METHODS |
167 | |
168 | =over 4 |
169 | |
170 | =item B<meta> |
171 | |
172 | This will return a B<Class::MOP::Class> instance which is related |
173 | to this class. |
174 | |
175 | =back |
176 | |
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177 | =head2 Methods which will die if you touch them. |
178 | |
179 | =over 4 |
180 | |
181 | =item B<add_attribute> |
182 | |
183 | =item B<add_method> |
184 | |
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185 | =item B<add_package_symbol> |
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186 | |
187 | =item B<alias_method> |
188 | |
189 | =item B<reinitialize> |
190 | |
191 | =item B<remove_attribute> |
192 | |
193 | =item B<remove_method> |
194 | |
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195 | =item B<remove_package_symbol> |
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196 | |
197 | =item B<superclasses> |
198 | |
199 | =back |
200 | |
201 | =head2 Cached methods |
202 | |
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203 | =over 4 |
204 | |
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205 | =item B<class_precedence_list> |
206 | |
207 | =item B<compute_all_applicable_attributes> |
208 | |
209 | =item B<get_meta_instance> |
210 | |
211 | =back |
212 | |
213 | =head2 Introspection and Construction |
214 | |
215 | =over 4 |
216 | |
217 | =item B<is_immutable> |
218 | |
219 | =item B<is_mutable> |
220 | |
221 | =item B<make_immutable> |
222 | |
223 | =item B<make_metaclass_immutable> |
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224 | |
225 | =back |
226 | |
227 | =head1 AUTHOR |
228 | |
229 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
230 | |
231 | =head1 COPYRIGHT AND LICENSE |
232 | |
233 | Copyright 2006 by Infinity Interactive, Inc. |
234 | |
235 | L<http://www.iinteractive.com> |
236 | |
237 | This library is free software; you can redistribute it and/or modify |
238 | it under the same terms as Perl itself. |
239 | |
240 | =cut |