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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 = '0.03'; |
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11 | our $AUTHORITY = 'cpan:STEVAN'; |
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12 | |
13 | use base 'Class::MOP::Class'; |
14 | |
15 | # methods which can *not* be called |
b1897d4d |
16 | for my $meth (qw( |
17 | add_method |
18 | alias_method |
19 | remove_method |
20 | add_attribute |
21 | remove_attribute |
22 | add_package_symbol |
23 | remove_package_symbol |
24 | )) { |
25 | no strict 'refs'; |
26 | *{$meth} = sub { |
27 | confess "Cannot call method '$meth' on an immutable instance"; |
28 | }; |
29 | } |
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30 | |
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31 | sub get_package_symbol { |
32 | my ($self, $variable) = @_; |
33 | my ($name, $sigil, $type) = $self->_deconstruct_variable_name($variable); |
34 | return *{$self->namespace->{$name}}{$type} |
35 | if exists $self->namespace->{$name}; |
36 | # NOTE: |
37 | # we have to do this here in order to preserve |
38 | # perl's autovivification of variables. However |
39 | # we do cut off direct access to add_package_symbol |
40 | # as shown above. |
41 | $self->Class::MOP::Package::add_package_symbol($variable); |
42 | } |
43 | |
857f87a7 |
44 | # NOTE: |
45 | # superclasses is an accessor, so |
46 | # it just cannot be changed |
47 | sub superclasses { |
48 | my $class = shift; |
49 | (!@_) || confess 'Cannot change the "superclasses" on an immmutable instance'; |
a5e51f0b |
50 | @{$class->get_package_symbol('@ISA')}; |
857f87a7 |
51 | } |
52 | |
53 | # predicates |
54 | |
55 | sub is_mutable { 0 } |
56 | sub is_immutable { 1 } |
57 | |
58 | sub make_immutable { () } |
59 | |
60 | sub make_metaclass_immutable { |
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61 | my ($class, $metaclass, %options) = @_; |
62 | |
4d47b77f |
63 | # NOTE: |
64 | # i really need the // (defined-or) operator here |
65 | $options{inline_accessors} = 1 unless exists $options{inline_accessors}; |
66 | $options{inline_constructor} = 1 unless exists $options{inline_constructor}; |
67 | $options{constructor_name} = 'new' unless exists $options{constructor_name}; |
68 | $options{debug} = 0 unless exists $options{debug}; |
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69 | |
70 | my $meta_instance = $metaclass->get_meta_instance; |
71 | $metaclass->{'___class_precedence_list'} = [ $metaclass->class_precedence_list ]; |
72 | $metaclass->{'___compute_all_applicable_attributes'} = [ $metaclass->compute_all_applicable_attributes ]; |
73 | $metaclass->{'___get_meta_instance'} = $meta_instance; |
74 | $metaclass->{'___original_class'} = blessed($metaclass); |
75 | |
76 | if ($options{inline_accessors}) { |
77 | foreach my $attr_name ($metaclass->get_attribute_list) { |
78 | my $attr = $metaclass->get_attribute($attr_name); |
79 | $attr->install_accessors(1); # inline the accessors |
80 | } |
81 | } |
82 | |
83 | if ($options{inline_constructor}) { |
84 | $metaclass->add_method( |
85 | $options{constructor_name}, |
86 | $class->_generate_inline_constructor( |
87 | \%options, |
88 | $meta_instance, |
89 | $metaclass->{'___compute_all_applicable_attributes'} |
90 | ) |
91 | ); |
92 | } |
ce2ae40f |
93 | |
94 | # now cache the method map ... |
95 | $metaclass->{'___method_map'} = $metaclass->get_method_map; |
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96 | |
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97 | bless $metaclass => $class; |
98 | } |
99 | |
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100 | sub _generate_inline_constructor { |
101 | my ($class, $options, $meta_instance, $attrs) = @_; |
102 | # TODO: |
103 | # the %options should also include a both |
104 | # a call 'initializer' and call 'SUPER::' |
105 | # options, which should cover approx 90% |
106 | # of the possible use cases (even if it |
107 | # requires some adaption on the part of |
108 | # the author, after all, nothing is free) |
109 | my $source = 'sub {'; |
110 | $source .= "\n" . 'my ($class, %params) = @_;'; |
111 | $source .= "\n" . 'my $instance = ' . $meta_instance->inline_create_instance('$class'); |
112 | $source .= ";\n" . (join ";\n" => map { |
113 | $class->_generate_slot_initializer($meta_instance, $attrs, $_) |
114 | } 0 .. (@$attrs - 1)); |
115 | $source .= ";\n" . 'return $instance'; |
116 | $source .= ";\n" . '}'; |
495af518 |
117 | warn $source if $options->{debug}; |
c0cbf4d9 |
118 | my $code = eval $source; |
119 | confess "Could not eval the constructor :\n\n$source\n\nbecause :\n\n$@" if $@; |
120 | return $code; |
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121 | } |
122 | |
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123 | sub _generate_slot_initializer { |
124 | my ($class, $meta_instance, $attrs, $index) = @_; |
125 | my $attr = $attrs->[$index]; |
126 | my $default; |
127 | if ($attr->has_default) { |
88dd563c |
128 | # NOTE: |
129 | # default values can either be CODE refs |
130 | # in which case we need to call them. Or |
131 | # they can be scalars (strings/numbers) |
132 | # in which case we can just deal with them |
133 | # in the code we eval. |
c0cbf4d9 |
134 | if ($attr->is_default_a_coderef) { |
135 | $default = '$attrs->[' . $index . ']->default($instance)'; |
136 | } |
137 | else { |
138 | $default = $attrs->[$index]->default; |
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139 | # make sure to quote strings ... |
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140 | unless (looks_like_number($default)) { |
141 | $default = "'$default'"; |
142 | } |
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143 | } |
144 | } |
145 | $meta_instance->inline_set_slot_value( |
146 | '$instance', |
373a16ae |
147 | ("'" . $attr->name . "'"), |
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148 | ('$params{\'' . $attr->init_arg . '\'}' . (defined $default ? (' || ' . $default) : '')) |
149 | ) |
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150 | } |
151 | |
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152 | # cached methods |
153 | |
154 | sub get_meta_instance { (shift)->{'___get_meta_instance'} } |
155 | sub class_precedence_list { @{(shift)->{'___class_precedence_list'}} } |
156 | sub compute_all_applicable_attributes { @{(shift)->{'___compute_all_applicable_attributes'}} } |
373a16ae |
157 | sub get_mutable_metaclass_name { (shift)->{'___original_class'} } |
ce2ae40f |
158 | sub get_method_map { (shift)->{'___method_map'} } |
c0cbf4d9 |
159 | |
857f87a7 |
160 | 1; |
161 | |
162 | __END__ |
163 | |
164 | =pod |
165 | |
166 | =head1 NAME |
167 | |
168 | Class::MOP::Class::Immutable - An immutable version of Class::MOP::Class |
169 | |
170 | =head1 SYNOPSIS |
171 | |
be960ba1 |
172 | package Point; |
173 | use metaclass; |
174 | |
175 | __PACKAGE__->meta->add_attribute('x' => (accessor => 'x', default => 10)); |
176 | __PACKAGE__->meta->add_attribute('y' => (accessor => 'y')); |
177 | |
178 | sub new { |
179 | my $class = shift; |
180 | $class->meta->new_object(@_); |
181 | } |
182 | |
183 | sub clear { |
184 | my $self = shift; |
185 | $self->x(0); |
186 | $self->y(0); |
187 | } |
188 | |
189 | __PACKAGE__->meta->make_immutable(); # close the class |
190 | |
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191 | =head1 DESCRIPTION |
192 | |
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193 | Class::MOP offers many benefits to object oriented development but it |
194 | comes at a cost. Pure Class::MOP classes can be quite a bit slower than |
195 | the typical hand coded Perl classes. This is because just about |
196 | I<everything> is recalculated on the fly, and nothing is cached. The |
197 | reason this is so, is because Perl itself allows you to modify virtually |
198 | everything at runtime. Class::MOP::Class::Immutable offers an alternative |
199 | to this. |
200 | |
201 | By making your class immutable, you are promising that you will not |
202 | modify your inheritence tree or the attributes of any classes in |
203 | that tree. Since runtime modifications like this are fairly atypical |
204 | (and usually recomended against), this is not usally a very hard promise |
205 | to make. For making this promise you are given a wide range of |
206 | optimization options which bring speed close to (and sometimes above) |
207 | those of typical hand coded Perl. |
208 | |
857f87a7 |
209 | =head1 METHODS |
210 | |
211 | =over 4 |
212 | |
213 | =item B<meta> |
214 | |
215 | This will return a B<Class::MOP::Class> instance which is related |
216 | to this class. |
217 | |
218 | =back |
219 | |
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220 | =head2 Introspection and Construction |
221 | |
222 | =over 4 |
223 | |
224 | =item B<make_metaclass_immutable> |
225 | |
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226 | The arguments to C<Class::MOP::Class::make_immutable> are passed |
227 | to this method, which |
228 | |
4d47b77f |
229 | =over 4 |
230 | |
231 | =item I<inline_accessors (Bool)> |
232 | |
233 | =item I<inline_constructor (Bool)> |
234 | |
235 | =item I<debug (Bool)> |
236 | |
237 | =item I<constructor_name (Str)> |
238 | |
239 | =back |
240 | |
241 | =item B<is_immutable> |
242 | |
243 | =item B<is_mutable> |
244 | |
245 | =item B<make_immutable> |
246 | |
373a16ae |
247 | =item B<get_mutable_metaclass_name> |
248 | |
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249 | =back |
250 | |
2243a22b |
251 | =head2 Methods which will die if you touch them. |
252 | |
253 | =over 4 |
254 | |
255 | =item B<add_attribute> |
256 | |
257 | =item B<add_method> |
258 | |
58d75218 |
259 | =item B<add_package_symbol> |
2243a22b |
260 | |
261 | =item B<alias_method> |
262 | |
2243a22b |
263 | =item B<remove_attribute> |
264 | |
265 | =item B<remove_method> |
266 | |
58d75218 |
267 | =item B<remove_package_symbol> |
2243a22b |
268 | |
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269 | =back |
270 | |
271 | =head2 Methods which work slightly differently. |
272 | |
273 | =over 4 |
274 | |
2243a22b |
275 | =item B<superclasses> |
276 | |
b6164407 |
277 | This method becomes read-only in an immutable class. |
278 | |
279 | =item B<get_package_symbol> |
280 | |
281 | This method must handle package variable autovivification |
282 | correctly, while still disallowing C<add_package_symbol>. |
283 | |
2243a22b |
284 | =back |
285 | |
286 | =head2 Cached methods |
287 | |
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288 | =over 4 |
289 | |
2243a22b |
290 | =item B<class_precedence_list> |
291 | |
292 | =item B<compute_all_applicable_attributes> |
293 | |
294 | =item B<get_meta_instance> |
295 | |
ce2ae40f |
296 | =item B<get_method_map> |
297 | |
2243a22b |
298 | =back |
299 | |
1a09d9cc |
300 | =head1 AUTHORS |
857f87a7 |
301 | |
302 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
303 | |
1a09d9cc |
304 | Yuval Kogman E<lt>nothingmuch@woobling.comE<gt> |
305 | |
857f87a7 |
306 | =head1 COPYRIGHT AND LICENSE |
307 | |
308 | Copyright 2006 by Infinity Interactive, Inc. |
309 | |
310 | L<http://www.iinteractive.com> |
311 | |
312 | This library is free software; you can redistribute it and/or modify |
313 | it under the same terms as Perl itself. |
314 | |
315 | =cut |