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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 | |
857f87a7 |
16 | sub add_method { confess 'Cannot call method "add_method" on an immutable instance' } |
17 | sub alias_method { confess 'Cannot call method "alias_method" on an immutable instance' } |
18 | sub remove_method { confess 'Cannot call method "remove_method" on an immutable instance' } |
19 | |
20 | sub add_attribute { confess 'Cannot call method "add_attribute" on an immutable instance' } |
21 | sub remove_attribute { confess 'Cannot call method "remove_attribute" on an immutable instance' } |
22 | |
58d75218 |
23 | sub add_package_symbol { confess 'Cannot call method "add_package_symbol" on an immutable instance' } |
24 | sub remove_package_symbol { confess 'Cannot call method "remove_package_symbol" on an immutable instance' } |
857f87a7 |
25 | |
26 | # NOTE: |
27 | # superclasses is an accessor, so |
28 | # it just cannot be changed |
29 | sub superclasses { |
30 | my $class = shift; |
31 | (!@_) || confess 'Cannot change the "superclasses" on an immmutable instance'; |
32 | no strict 'refs'; |
33 | @{$class->name . '::ISA'}; |
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 | |
4d47b77f |
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 | |
857f87a7 |
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 $code; |
857f87a7 |
101 | } |
102 | |
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103 | sub _generate_slot_initializer { |
104 | my ($class, $meta_instance, $attrs, $index) = @_; |
105 | my $attr = $attrs->[$index]; |
106 | my $default; |
107 | if ($attr->has_default) { |
108 | if ($attr->is_default_a_coderef) { |
109 | $default = '$attrs->[' . $index . ']->default($instance)'; |
110 | } |
111 | else { |
112 | $default = $attrs->[$index]->default; |
113 | unless (looks_like_number($default)) { |
114 | $default = "'$default'"; |
115 | } |
116 | # TODO: |
117 | # we should use Data::Dumper to |
118 | # output any ref's here, obviously |
119 | # we cannot handle Scalar refs, but |
120 | # it should work for Array and Hash |
121 | # refs pretty well. |
122 | } |
123 | } |
124 | $meta_instance->inline_set_slot_value( |
125 | '$instance', |
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126 | ("'" . $attr->name . "'"), |
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127 | ('$params{\'' . $attr->init_arg . '\'}' . (defined $default ? (' || ' . $default) : '')) |
128 | ) |
857f87a7 |
129 | } |
130 | |
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131 | # cached methods |
132 | |
133 | sub get_meta_instance { (shift)->{'___get_meta_instance'} } |
134 | sub class_precedence_list { @{(shift)->{'___class_precedence_list'}} } |
135 | sub compute_all_applicable_attributes { @{(shift)->{'___compute_all_applicable_attributes'}} } |
373a16ae |
136 | sub get_mutable_metaclass_name { (shift)->{'___original_class'} } |
c0cbf4d9 |
137 | |
857f87a7 |
138 | 1; |
139 | |
140 | __END__ |
141 | |
142 | =pod |
143 | |
144 | =head1 NAME |
145 | |
146 | Class::MOP::Class::Immutable - An immutable version of Class::MOP::Class |
147 | |
148 | =head1 SYNOPSIS |
149 | |
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150 | package Point; |
151 | use metaclass; |
152 | |
153 | __PACKAGE__->meta->add_attribute('x' => (accessor => 'x', default => 10)); |
154 | __PACKAGE__->meta->add_attribute('y' => (accessor => 'y')); |
155 | |
156 | sub new { |
157 | my $class = shift; |
158 | $class->meta->new_object(@_); |
159 | } |
160 | |
161 | sub clear { |
162 | my $self = shift; |
163 | $self->x(0); |
164 | $self->y(0); |
165 | } |
166 | |
167 | __PACKAGE__->meta->make_immutable(); # close the class |
168 | |
857f87a7 |
169 | =head1 DESCRIPTION |
170 | |
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171 | Class::MOP offers many benefits to object oriented development but it |
172 | comes at a cost. Pure Class::MOP classes can be quite a bit slower than |
173 | the typical hand coded Perl classes. This is because just about |
174 | I<everything> is recalculated on the fly, and nothing is cached. The |
175 | reason this is so, is because Perl itself allows you to modify virtually |
176 | everything at runtime. Class::MOP::Class::Immutable offers an alternative |
177 | to this. |
178 | |
179 | By making your class immutable, you are promising that you will not |
180 | modify your inheritence tree or the attributes of any classes in |
181 | that tree. Since runtime modifications like this are fairly atypical |
182 | (and usually recomended against), this is not usally a very hard promise |
183 | to make. For making this promise you are given a wide range of |
184 | optimization options which bring speed close to (and sometimes above) |
185 | those of typical hand coded Perl. |
186 | |
857f87a7 |
187 | =head1 METHODS |
188 | |
189 | =over 4 |
190 | |
191 | =item B<meta> |
192 | |
193 | This will return a B<Class::MOP::Class> instance which is related |
194 | to this class. |
195 | |
196 | =back |
197 | |
4d47b77f |
198 | =head2 Introspection and Construction |
199 | |
200 | =over 4 |
201 | |
202 | =item B<make_metaclass_immutable> |
203 | |
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204 | The arguments to C<Class::MOP::Class::make_immutable> are passed |
205 | to this method, which |
206 | |
4d47b77f |
207 | =over 4 |
208 | |
209 | =item I<inline_accessors (Bool)> |
210 | |
211 | =item I<inline_constructor (Bool)> |
212 | |
213 | =item I<debug (Bool)> |
214 | |
215 | =item I<constructor_name (Str)> |
216 | |
217 | =back |
218 | |
219 | =item B<is_immutable> |
220 | |
221 | =item B<is_mutable> |
222 | |
223 | =item B<make_immutable> |
224 | |
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225 | =item B<get_mutable_metaclass_name> |
226 | |
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227 | =back |
228 | |
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229 | =head2 Methods which will die if you touch them. |
230 | |
231 | =over 4 |
232 | |
233 | =item B<add_attribute> |
234 | |
235 | =item B<add_method> |
236 | |
58d75218 |
237 | =item B<add_package_symbol> |
2243a22b |
238 | |
239 | =item B<alias_method> |
240 | |
2243a22b |
241 | =item B<remove_attribute> |
242 | |
243 | =item B<remove_method> |
244 | |
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245 | =item B<remove_package_symbol> |
2243a22b |
246 | |
247 | =item B<superclasses> |
248 | |
249 | =back |
250 | |
251 | =head2 Cached methods |
252 | |
857f87a7 |
253 | =over 4 |
254 | |
2243a22b |
255 | =item B<class_precedence_list> |
256 | |
257 | =item B<compute_all_applicable_attributes> |
258 | |
259 | =item B<get_meta_instance> |
260 | |
261 | =back |
262 | |
857f87a7 |
263 | =head1 AUTHOR |
264 | |
265 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
266 | |
267 | =head1 COPYRIGHT AND LICENSE |
268 | |
269 | Copyright 2006 by Infinity Interactive, Inc. |
270 | |
271 | L<http://www.iinteractive.com> |
272 | |
273 | This library is free software; you can redistribute it and/or modify |
274 | it under the same terms as Perl itself. |
275 | |
276 | =cut |