Commit | Line | Data |
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'; |
f0480c45 |
11 | our $AUTHORITY = 'cpan:STEVAN'; |
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12 | |
13 | use base 'Class::MOP::Class'; |
14 | |
dc76a410 |
15 | # enforce the meta-circularity here |
16 | # and hide the Immutable part |
17 | |
18 | sub meta { |
19 | my $self = shift; |
20 | # if it is not blessed, then someone is asking |
21 | # for the meta of Class::MOP::Class::Immutable |
22 | return Class::MOP::Class->initialize($self) unless blessed($self); |
23 | # otherwise, they are asking for the metaclass |
24 | # which has been made immutable, which is itself |
25 | return $self; |
26 | } |
27 | |
857f87a7 |
28 | # methods which can *not* be called |
b1897d4d |
29 | for my $meth (qw( |
30 | add_method |
31 | alias_method |
32 | remove_method |
33 | add_attribute |
34 | remove_attribute |
35 | add_package_symbol |
36 | remove_package_symbol |
37 | )) { |
38 | no strict 'refs'; |
39 | *{$meth} = sub { |
40 | confess "Cannot call method '$meth' on an immutable instance"; |
41 | }; |
42 | } |
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43 | |
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44 | sub get_package_symbol { |
45 | my ($self, $variable) = @_; |
46 | my ($name, $sigil, $type) = $self->_deconstruct_variable_name($variable); |
47 | return *{$self->namespace->{$name}}{$type} |
48 | if exists $self->namespace->{$name}; |
49 | # NOTE: |
50 | # we have to do this here in order to preserve |
51 | # perl's autovivification of variables. However |
52 | # we do cut off direct access to add_package_symbol |
53 | # as shown above. |
54 | $self->Class::MOP::Package::add_package_symbol($variable); |
55 | } |
56 | |
857f87a7 |
57 | # NOTE: |
58 | # superclasses is an accessor, so |
59 | # it just cannot be changed |
60 | sub superclasses { |
61 | my $class = shift; |
62 | (!@_) || confess 'Cannot change the "superclasses" on an immmutable instance'; |
a5e51f0b |
63 | @{$class->get_package_symbol('@ISA')}; |
857f87a7 |
64 | } |
65 | |
66 | # predicates |
67 | |
68 | sub is_mutable { 0 } |
69 | sub is_immutable { 1 } |
70 | |
71 | sub make_immutable { () } |
72 | |
73 | sub make_metaclass_immutable { |
c0cbf4d9 |
74 | my ($class, $metaclass, %options) = @_; |
75 | |
4d47b77f |
76 | # NOTE: |
77 | # i really need the // (defined-or) operator here |
78 | $options{inline_accessors} = 1 unless exists $options{inline_accessors}; |
79 | $options{inline_constructor} = 1 unless exists $options{inline_constructor}; |
80 | $options{constructor_name} = 'new' unless exists $options{constructor_name}; |
81 | $options{debug} = 0 unless exists $options{debug}; |
c0cbf4d9 |
82 | |
83 | my $meta_instance = $metaclass->get_meta_instance; |
84 | $metaclass->{'___class_precedence_list'} = [ $metaclass->class_precedence_list ]; |
85 | $metaclass->{'___compute_all_applicable_attributes'} = [ $metaclass->compute_all_applicable_attributes ]; |
86 | $metaclass->{'___get_meta_instance'} = $meta_instance; |
87 | $metaclass->{'___original_class'} = blessed($metaclass); |
88 | |
89 | if ($options{inline_accessors}) { |
90 | foreach my $attr_name ($metaclass->get_attribute_list) { |
91 | my $attr = $metaclass->get_attribute($attr_name); |
92 | $attr->install_accessors(1); # inline the accessors |
93 | } |
94 | } |
95 | |
96 | if ($options{inline_constructor}) { |
97 | $metaclass->add_method( |
98 | $options{constructor_name}, |
99 | $class->_generate_inline_constructor( |
100 | \%options, |
101 | $meta_instance, |
102 | $metaclass->{'___compute_all_applicable_attributes'} |
103 | ) |
104 | ); |
105 | } |
ce2ae40f |
106 | |
107 | # now cache the method map ... |
108 | $metaclass->{'___method_map'} = $metaclass->get_method_map; |
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109 | |
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110 | bless $metaclass => $class; |
111 | } |
112 | |
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113 | sub _generate_inline_constructor { |
114 | my ($class, $options, $meta_instance, $attrs) = @_; |
115 | # TODO: |
116 | # the %options should also include a both |
117 | # a call 'initializer' and call 'SUPER::' |
118 | # options, which should cover approx 90% |
119 | # of the possible use cases (even if it |
120 | # requires some adaption on the part of |
121 | # the author, after all, nothing is free) |
122 | my $source = 'sub {'; |
123 | $source .= "\n" . 'my ($class, %params) = @_;'; |
124 | $source .= "\n" . 'my $instance = ' . $meta_instance->inline_create_instance('$class'); |
125 | $source .= ";\n" . (join ";\n" => map { |
126 | $class->_generate_slot_initializer($meta_instance, $attrs, $_) |
127 | } 0 .. (@$attrs - 1)); |
128 | $source .= ";\n" . 'return $instance'; |
129 | $source .= ";\n" . '}'; |
495af518 |
130 | warn $source if $options->{debug}; |
c0cbf4d9 |
131 | my $code = eval $source; |
132 | confess "Could not eval the constructor :\n\n$source\n\nbecause :\n\n$@" if $@; |
133 | return $code; |
857f87a7 |
134 | } |
135 | |
c0cbf4d9 |
136 | sub _generate_slot_initializer { |
137 | my ($class, $meta_instance, $attrs, $index) = @_; |
138 | my $attr = $attrs->[$index]; |
139 | my $default; |
140 | if ($attr->has_default) { |
88dd563c |
141 | # NOTE: |
142 | # default values can either be CODE refs |
143 | # in which case we need to call them. Or |
144 | # they can be scalars (strings/numbers) |
145 | # in which case we can just deal with them |
146 | # in the code we eval. |
c0cbf4d9 |
147 | if ($attr->is_default_a_coderef) { |
148 | $default = '$attrs->[' . $index . ']->default($instance)'; |
149 | } |
150 | else { |
151 | $default = $attrs->[$index]->default; |
88dd563c |
152 | # make sure to quote strings ... |
c0cbf4d9 |
153 | unless (looks_like_number($default)) { |
154 | $default = "'$default'"; |
155 | } |
c0cbf4d9 |
156 | } |
157 | } |
158 | $meta_instance->inline_set_slot_value( |
159 | '$instance', |
373a16ae |
160 | ("'" . $attr->name . "'"), |
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161 | ('$params{\'' . $attr->init_arg . '\'}' . (defined $default ? (' || ' . $default) : '')) |
162 | ) |
857f87a7 |
163 | } |
164 | |
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165 | # cached methods |
166 | |
167 | sub get_meta_instance { (shift)->{'___get_meta_instance'} } |
168 | sub class_precedence_list { @{(shift)->{'___class_precedence_list'}} } |
169 | sub compute_all_applicable_attributes { @{(shift)->{'___compute_all_applicable_attributes'}} } |
373a16ae |
170 | sub get_mutable_metaclass_name { (shift)->{'___original_class'} } |
ce2ae40f |
171 | sub get_method_map { (shift)->{'___method_map'} } |
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172 | |
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173 | 1; |
174 | |
175 | __END__ |
176 | |
177 | =pod |
178 | |
179 | =head1 NAME |
180 | |
181 | Class::MOP::Class::Immutable - An immutable version of Class::MOP::Class |
182 | |
183 | =head1 SYNOPSIS |
184 | |
be960ba1 |
185 | package Point; |
186 | use metaclass; |
187 | |
188 | __PACKAGE__->meta->add_attribute('x' => (accessor => 'x', default => 10)); |
189 | __PACKAGE__->meta->add_attribute('y' => (accessor => 'y')); |
190 | |
191 | sub new { |
192 | my $class = shift; |
193 | $class->meta->new_object(@_); |
194 | } |
195 | |
196 | sub clear { |
197 | my $self = shift; |
198 | $self->x(0); |
199 | $self->y(0); |
200 | } |
201 | |
202 | __PACKAGE__->meta->make_immutable(); # close the class |
203 | |
857f87a7 |
204 | =head1 DESCRIPTION |
205 | |
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206 | Class::MOP offers many benefits to object oriented development but it |
207 | comes at a cost. Pure Class::MOP classes can be quite a bit slower than |
208 | the typical hand coded Perl classes. This is because just about |
209 | I<everything> is recalculated on the fly, and nothing is cached. The |
210 | reason this is so, is because Perl itself allows you to modify virtually |
211 | everything at runtime. Class::MOP::Class::Immutable offers an alternative |
212 | to this. |
213 | |
214 | By making your class immutable, you are promising that you will not |
215 | modify your inheritence tree or the attributes of any classes in |
216 | that tree. Since runtime modifications like this are fairly atypical |
217 | (and usually recomended against), this is not usally a very hard promise |
218 | to make. For making this promise you are given a wide range of |
219 | optimization options which bring speed close to (and sometimes above) |
220 | those of typical hand coded Perl. |
221 | |
857f87a7 |
222 | =head1 METHODS |
223 | |
224 | =over 4 |
225 | |
226 | =item B<meta> |
227 | |
228 | This will return a B<Class::MOP::Class> instance which is related |
229 | to this class. |
230 | |
231 | =back |
232 | |
4d47b77f |
233 | =head2 Introspection and Construction |
234 | |
235 | =over 4 |
236 | |
237 | =item B<make_metaclass_immutable> |
238 | |
be960ba1 |
239 | The arguments to C<Class::MOP::Class::make_immutable> are passed |
240 | to this method, which |
241 | |
4d47b77f |
242 | =over 4 |
243 | |
244 | =item I<inline_accessors (Bool)> |
245 | |
246 | =item I<inline_constructor (Bool)> |
247 | |
248 | =item I<debug (Bool)> |
249 | |
250 | =item I<constructor_name (Str)> |
251 | |
252 | =back |
253 | |
254 | =item B<is_immutable> |
255 | |
256 | =item B<is_mutable> |
257 | |
258 | =item B<make_immutable> |
259 | |
373a16ae |
260 | =item B<get_mutable_metaclass_name> |
261 | |
4d47b77f |
262 | =back |
263 | |
2243a22b |
264 | =head2 Methods which will die if you touch them. |
265 | |
266 | =over 4 |
267 | |
268 | =item B<add_attribute> |
269 | |
270 | =item B<add_method> |
271 | |
58d75218 |
272 | =item B<add_package_symbol> |
2243a22b |
273 | |
274 | =item B<alias_method> |
275 | |
2243a22b |
276 | =item B<remove_attribute> |
277 | |
278 | =item B<remove_method> |
279 | |
58d75218 |
280 | =item B<remove_package_symbol> |
2243a22b |
281 | |
b6164407 |
282 | =back |
283 | |
284 | =head2 Methods which work slightly differently. |
285 | |
286 | =over 4 |
287 | |
2243a22b |
288 | =item B<superclasses> |
289 | |
b6164407 |
290 | This method becomes read-only in an immutable class. |
291 | |
292 | =item B<get_package_symbol> |
293 | |
294 | This method must handle package variable autovivification |
295 | correctly, while still disallowing C<add_package_symbol>. |
296 | |
2243a22b |
297 | =back |
298 | |
299 | =head2 Cached methods |
300 | |
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301 | =over 4 |
302 | |
2243a22b |
303 | =item B<class_precedence_list> |
304 | |
305 | =item B<compute_all_applicable_attributes> |
306 | |
307 | =item B<get_meta_instance> |
308 | |
ce2ae40f |
309 | =item B<get_method_map> |
310 | |
2243a22b |
311 | =back |
312 | |
1a09d9cc |
313 | =head1 AUTHORS |
857f87a7 |
314 | |
315 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
316 | |
1a09d9cc |
317 | Yuval Kogman E<lt>nothingmuch@woobling.comE<gt> |
318 | |
857f87a7 |
319 | =head1 COPYRIGHT AND LICENSE |
320 | |
321 | Copyright 2006 by Infinity Interactive, Inc. |
322 | |
323 | L<http://www.iinteractive.com> |
324 | |
325 | This library is free software; you can redistribute it and/or modify |
326 | it under the same terms as Perl itself. |
327 | |
328 | =cut |