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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 | |
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10 | our $VERSION = '0.02'; |
11 | our $AUTHORITY = 'cpan:STEVAN'; |
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12 | |
13 | use base 'Class::MOP::Class'; |
14 | |
15 | # methods which can *not* be called |
16 | |
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17 | sub add_method { confess 'Cannot call method "add_method" on an immutable instance' } |
18 | sub alias_method { confess 'Cannot call method "alias_method" on an immutable instance' } |
19 | sub remove_method { confess 'Cannot call method "remove_method" on an immutable instance' } |
20 | |
21 | sub add_attribute { confess 'Cannot call method "add_attribute" on an immutable instance' } |
22 | sub remove_attribute { confess 'Cannot call method "remove_attribute" on an immutable instance' } |
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23 | |
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24 | sub add_package_symbol { confess 'Cannot call method "add_package_symbol" on an immutable instance' } |
25 | sub remove_package_symbol { confess 'Cannot call method "remove_package_symbol" on an immutable instance' } |
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26 | |
27 | # NOTE: |
28 | # superclasses is an accessor, so |
29 | # it just cannot be changed |
30 | sub superclasses { |
31 | my $class = shift; |
32 | (!@_) || confess 'Cannot change the "superclasses" on an immmutable instance'; |
a5e51f0b |
33 | @{$class->get_package_symbol('@ISA')}; |
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34 | } |
35 | |
36 | # predicates |
37 | |
38 | sub is_mutable { 0 } |
39 | sub is_immutable { 1 } |
40 | |
41 | sub make_immutable { () } |
42 | |
43 | sub make_metaclass_immutable { |
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44 | my ($class, $metaclass, %options) = @_; |
45 | |
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46 | # NOTE: |
47 | # i really need the // (defined-or) operator here |
48 | $options{inline_accessors} = 1 unless exists $options{inline_accessors}; |
49 | $options{inline_constructor} = 1 unless exists $options{inline_constructor}; |
50 | $options{constructor_name} = 'new' unless exists $options{constructor_name}; |
51 | $options{debug} = 0 unless exists $options{debug}; |
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52 | |
53 | my $meta_instance = $metaclass->get_meta_instance; |
54 | $metaclass->{'___class_precedence_list'} = [ $metaclass->class_precedence_list ]; |
55 | $metaclass->{'___compute_all_applicable_attributes'} = [ $metaclass->compute_all_applicable_attributes ]; |
56 | $metaclass->{'___get_meta_instance'} = $meta_instance; |
57 | $metaclass->{'___original_class'} = blessed($metaclass); |
58 | |
59 | if ($options{inline_accessors}) { |
60 | foreach my $attr_name ($metaclass->get_attribute_list) { |
61 | my $attr = $metaclass->get_attribute($attr_name); |
62 | $attr->install_accessors(1); # inline the accessors |
63 | } |
64 | } |
65 | |
66 | if ($options{inline_constructor}) { |
67 | $metaclass->add_method( |
68 | $options{constructor_name}, |
69 | $class->_generate_inline_constructor( |
70 | \%options, |
71 | $meta_instance, |
72 | $metaclass->{'___compute_all_applicable_attributes'} |
73 | ) |
74 | ); |
75 | } |
76 | |
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77 | bless $metaclass => $class; |
78 | } |
79 | |
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80 | sub _generate_inline_constructor { |
81 | my ($class, $options, $meta_instance, $attrs) = @_; |
82 | # TODO: |
83 | # the %options should also include a both |
84 | # a call 'initializer' and call 'SUPER::' |
85 | # options, which should cover approx 90% |
86 | # of the possible use cases (even if it |
87 | # requires some adaption on the part of |
88 | # the author, after all, nothing is free) |
89 | my $source = 'sub {'; |
90 | $source .= "\n" . 'my ($class, %params) = @_;'; |
91 | $source .= "\n" . 'my $instance = ' . $meta_instance->inline_create_instance('$class'); |
92 | $source .= ";\n" . (join ";\n" => map { |
93 | $class->_generate_slot_initializer($meta_instance, $attrs, $_) |
94 | } 0 .. (@$attrs - 1)); |
95 | $source .= ";\n" . 'return $instance'; |
96 | $source .= ";\n" . '}'; |
495af518 |
97 | warn $source if $options->{debug}; |
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98 | my $code = eval $source; |
99 | confess "Could not eval the constructor :\n\n$source\n\nbecause :\n\n$@" if $@; |
100 | return $code; |
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101 | } |
102 | |
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103 | sub _generate_slot_initializer { |
104 | my ($class, $meta_instance, $attrs, $index) = @_; |
105 | my $attr = $attrs->[$index]; |
106 | my $default; |
107 | if ($attr->has_default) { |
88dd563c |
108 | # NOTE: |
109 | # default values can either be CODE refs |
110 | # in which case we need to call them. Or |
111 | # they can be scalars (strings/numbers) |
112 | # in which case we can just deal with them |
113 | # in the code we eval. |
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114 | if ($attr->is_default_a_coderef) { |
115 | $default = '$attrs->[' . $index . ']->default($instance)'; |
116 | } |
117 | else { |
118 | $default = $attrs->[$index]->default; |
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119 | # make sure to quote strings ... |
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120 | unless (looks_like_number($default)) { |
121 | $default = "'$default'"; |
122 | } |
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123 | } |
124 | } |
125 | $meta_instance->inline_set_slot_value( |
126 | '$instance', |
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127 | ("'" . $attr->name . "'"), |
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128 | ('$params{\'' . $attr->init_arg . '\'}' . (defined $default ? (' || ' . $default) : '')) |
129 | ) |
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130 | } |
131 | |
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132 | # cached methods |
133 | |
134 | sub get_meta_instance { (shift)->{'___get_meta_instance'} } |
135 | sub class_precedence_list { @{(shift)->{'___class_precedence_list'}} } |
136 | sub compute_all_applicable_attributes { @{(shift)->{'___compute_all_applicable_attributes'}} } |
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137 | sub get_mutable_metaclass_name { (shift)->{'___original_class'} } |
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138 | |
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139 | 1; |
140 | |
141 | __END__ |
142 | |
143 | =pod |
144 | |
145 | =head1 NAME |
146 | |
147 | Class::MOP::Class::Immutable - An immutable version of Class::MOP::Class |
148 | |
149 | =head1 SYNOPSIS |
150 | |
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151 | package Point; |
152 | use metaclass; |
153 | |
154 | __PACKAGE__->meta->add_attribute('x' => (accessor => 'x', default => 10)); |
155 | __PACKAGE__->meta->add_attribute('y' => (accessor => 'y')); |
156 | |
157 | sub new { |
158 | my $class = shift; |
159 | $class->meta->new_object(@_); |
160 | } |
161 | |
162 | sub clear { |
163 | my $self = shift; |
164 | $self->x(0); |
165 | $self->y(0); |
166 | } |
167 | |
168 | __PACKAGE__->meta->make_immutable(); # close the class |
169 | |
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170 | =head1 DESCRIPTION |
171 | |
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172 | Class::MOP offers many benefits to object oriented development but it |
173 | comes at a cost. Pure Class::MOP classes can be quite a bit slower than |
174 | the typical hand coded Perl classes. This is because just about |
175 | I<everything> is recalculated on the fly, and nothing is cached. The |
176 | reason this is so, is because Perl itself allows you to modify virtually |
177 | everything at runtime. Class::MOP::Class::Immutable offers an alternative |
178 | to this. |
179 | |
180 | By making your class immutable, you are promising that you will not |
181 | modify your inheritence tree or the attributes of any classes in |
182 | that tree. Since runtime modifications like this are fairly atypical |
183 | (and usually recomended against), this is not usally a very hard promise |
184 | to make. For making this promise you are given a wide range of |
185 | optimization options which bring speed close to (and sometimes above) |
186 | those of typical hand coded Perl. |
187 | |
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188 | =head1 METHODS |
189 | |
190 | =over 4 |
191 | |
192 | =item B<meta> |
193 | |
194 | This will return a B<Class::MOP::Class> instance which is related |
195 | to this class. |
196 | |
197 | =back |
198 | |
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199 | =head2 Introspection and Construction |
200 | |
201 | =over 4 |
202 | |
203 | =item B<make_metaclass_immutable> |
204 | |
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205 | The arguments to C<Class::MOP::Class::make_immutable> are passed |
206 | to this method, which |
207 | |
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208 | =over 4 |
209 | |
210 | =item I<inline_accessors (Bool)> |
211 | |
212 | =item I<inline_constructor (Bool)> |
213 | |
214 | =item I<debug (Bool)> |
215 | |
216 | =item I<constructor_name (Str)> |
217 | |
218 | =back |
219 | |
220 | =item B<is_immutable> |
221 | |
222 | =item B<is_mutable> |
223 | |
224 | =item B<make_immutable> |
225 | |
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226 | =item B<get_mutable_metaclass_name> |
227 | |
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228 | =back |
229 | |
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230 | =head2 Methods which will die if you touch them. |
231 | |
232 | =over 4 |
233 | |
234 | =item B<add_attribute> |
235 | |
236 | =item B<add_method> |
237 | |
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238 | =item B<add_package_symbol> |
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239 | |
240 | =item B<alias_method> |
241 | |
2243a22b |
242 | =item B<remove_attribute> |
243 | |
244 | =item B<remove_method> |
245 | |
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246 | =item B<remove_package_symbol> |
2243a22b |
247 | |
248 | =item B<superclasses> |
249 | |
250 | =back |
251 | |
252 | =head2 Cached methods |
253 | |
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254 | =over 4 |
255 | |
2243a22b |
256 | =item B<class_precedence_list> |
257 | |
258 | =item B<compute_all_applicable_attributes> |
259 | |
260 | =item B<get_meta_instance> |
261 | |
262 | =back |
263 | |
1a09d9cc |
264 | =head1 AUTHORS |
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265 | |
266 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
267 | |
1a09d9cc |
268 | Yuval Kogman E<lt>nothingmuch@woobling.comE<gt> |
269 | |
857f87a7 |
270 | =head1 COPYRIGHT AND LICENSE |
271 | |
272 | Copyright 2006 by Infinity Interactive, Inc. |
273 | |
274 | L<http://www.iinteractive.com> |
275 | |
276 | This library is free software; you can redistribute it and/or modify |
277 | it under the same terms as Perl itself. |
278 | |
279 | =cut |