Commit | Line | Data |
c23184fc |
1 | |
2 | package Class::MOP::Immutable; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
7 | use Class::MOP::Method::Constructor; |
8 | |
9 | use Carp 'confess'; |
10 | use Scalar::Util 'blessed'; |
11 | |
12 | our $VERSION = '0.01'; |
13 | our $AUTHORITY = 'cpan:STEVAN'; |
14 | |
15 | sub new { |
16 | my ($class, $metaclass, $options) = @_; |
17 | |
18 | my $self = bless { |
19 | '$!metaclass' => $metaclass, |
20 | '%!options' => $options, |
21 | '$!immutable_metaclass' => undef, |
22 | } => $class; |
23 | |
24 | # NOTE: |
25 | # we initialize the immutable |
26 | # version of the metaclass here |
27 | $self->create_immutable_metaclass; |
28 | |
29 | return $self; |
30 | } |
31 | |
32 | sub immutable_metaclass { (shift)->{'$!immutable_metaclass'} } |
33 | sub metaclass { (shift)->{'$!metaclass'} } |
34 | sub options { (shift)->{'%!options'} } |
35 | |
36 | sub create_immutable_metaclass { |
37 | my $self = shift; |
38 | |
39 | # NOTE: |
40 | # The immutable version of the |
41 | # metaclass is just a anon-class |
42 | # which shadows the methods |
43 | # appropriately |
44 | $self->{'$!immutable_metaclass'} = Class::MOP::Class->create_anon_class( |
45 | superclasses => [ blessed($self->metaclass) ], |
46 | methods => $self->create_methods_for_immutable_metaclass, |
47 | ); |
48 | } |
49 | |
50 | my %DEFAULT_METHODS = ( |
51 | meta => sub { |
52 | my $self = shift; |
53 | # if it is not blessed, then someone is asking |
54 | # for the meta of Class::MOP::Class::Immutable |
55 | return Class::MOP::Class->initialize($self) unless blessed($self); |
56 | # otherwise, they are asking for the metaclass |
57 | # which has been made immutable, which is itself |
58 | return $self; |
59 | }, |
60 | is_mutable => sub { 0 }, |
61 | is_immutable => sub { 1 }, |
62 | make_immutable => sub { ( ) }, |
63 | ); |
64 | |
65 | # NOTE: |
66 | # this will actually convert the |
67 | # existing metaclass to an immutable |
68 | # version of itself |
69 | sub make_metaclass_immutable { |
70 | my ($self, $metaclass, %options) = @_; |
71 | |
72 | $options{inline_accessors} = 1 unless exists $options{inline_accessors}; |
73 | $options{inline_constructor} = 1 unless exists $options{inline_constructor}; |
74 | $options{inline_destructor} = 0 unless exists $options{inline_destructor}; |
75 | $options{constructor_name} = 'new' unless exists $options{constructor_name}; |
76 | $options{debug} = 0 unless exists $options{debug}; |
77 | |
78 | if ($options{inline_accessors}) { |
79 | foreach my $attr_name ($metaclass->get_attribute_list) { |
80 | # inline the accessors |
81 | $metaclass->get_attribute($attr_name) |
82 | ->install_accessors(1); |
83 | } |
84 | } |
85 | |
86 | if ($options{inline_constructor}) { |
87 | my $constructor_class = $options{constructor_class} || 'Class::MOP::Method::Constructor'; |
88 | |
89 | $metaclass->add_method( |
90 | $options{constructor_name}, |
91 | $constructor_class->new( |
92 | options => \%options, |
93 | metaclass => $metaclass, |
94 | ) |
95 | ) unless $metaclass->has_method($options{constructor_name}); |
96 | } |
97 | |
98 | if ($options{inline_destructor}) { |
99 | (exists $options{destructor_class}) |
100 | || confess "The 'inline_destructor' option is present, but " |
101 | . "no destructor class was specified"; |
102 | |
103 | my $destructor_class = $options{destructor_class}; |
104 | |
105 | my $destructor = $destructor_class->new( |
106 | options => \%options, |
107 | metaclass => $metaclass, |
108 | ); |
109 | |
110 | $metaclass->add_method('DESTROY' => $destructor) |
111 | # NOTE: |
112 | # we allow the destructor to determine |
113 | # if it is needed or not, it can perform |
114 | # all sorts of checks because it has the |
115 | # metaclass instance |
116 | if $destructor->is_needed; |
117 | } |
118 | |
119 | my $memoized_methods = $self->options->{memoize}; |
120 | foreach my $method_name (keys %{$memoized_methods}) { |
121 | my $type = $memoized_methods->{$method_name}; |
122 | |
123 | ($metaclass->can($method_name)) |
124 | || confess "Could not find the method '$method_name' in " . $metaclass->name; |
125 | |
126 | my $memoized_method; |
127 | if ($type eq 'ARRAY') { |
128 | $metaclass->{'___' . $method_name} = [ $metaclass->$method_name ]; |
129 | } |
130 | elsif ($type eq 'HASH') { |
131 | $metaclass->{'___' . $method_name} = { $metaclass->$method_name }; |
132 | } |
133 | elsif ($type eq 'SCALAR') { |
134 | $metaclass->{'___' . $method_name} = $metaclass->$method_name; |
135 | } |
136 | } |
137 | $metaclass->{'___original_class'} = blessed($metaclass); |
138 | |
139 | bless $metaclass => $self->immutable_metaclass->name; |
140 | } |
141 | |
142 | sub create_methods_for_immutable_metaclass { |
143 | my $self = shift; |
144 | |
145 | my %methods = %DEFAULT_METHODS; |
146 | |
147 | foreach my $read_only_method (@{$self->options->{read_only}}) { |
148 | my $method = $self->metaclass->meta->find_method_by_name($read_only_method); |
149 | |
150 | (defined $method) |
151 | || confess "Could not find the method '$read_only_method' in " . $self->metaclass->name; |
152 | |
153 | $methods{$read_only_method} = sub { |
154 | confess "This method is read-only" if scalar @_ > 1; |
155 | goto &{$method->body} |
156 | }; |
157 | } |
158 | |
159 | foreach my $cannot_call_method (@{$self->options->{cannot_call}}) { |
160 | $methods{$cannot_call_method} = sub { |
161 | confess "This method ($cannot_call_method) cannot be called on an immutable instance"; |
162 | }; |
163 | } |
164 | |
165 | my $memoized_methods = $self->options->{memoize}; |
166 | |
167 | foreach my $method_name (keys %{$memoized_methods}) { |
168 | my $type = $memoized_methods->{$method_name}; |
169 | if ($type eq 'ARRAY') { |
170 | $methods{$method_name} = sub { @{$_[0]->{'___' . $method_name}} }; |
171 | } |
172 | elsif ($type eq 'HASH') { |
173 | $methods{$method_name} = sub { %{$_[0]->{'___' . $method_name}} }; |
174 | } |
175 | elsif ($type eq 'SCALAR') { |
176 | $methods{$method_name} = sub { $_[0]->{'___' . $method_name} }; |
177 | } |
178 | } |
179 | |
180 | $methods{get_mutable_metaclass_name} = sub { (shift)->{'___original_class'} }; |
181 | |
182 | return \%methods; |
183 | } |
184 | |
185 | 1; |
186 | |
187 | __END__ |
188 | |
189 | =pod |
190 | |
191 | =head1 NAME |
192 | |
193 | Class::MOP::Immutable - A class to transform Class::MOP::Class metaclasses |
194 | |
195 | =head1 SYNOPSIS |
196 | |
96e38ba6 |
197 | use Class::MOP::Immutable; |
198 | |
199 | my $immutable_metaclass = Class::MOP::Immutable->new($metaclass, { |
200 | read_only => [qw/superclasses/], |
201 | cannot_call => [qw/ |
202 | add_method |
203 | alias_method |
204 | remove_method |
205 | add_attribute |
206 | remove_attribute |
207 | add_package_symbol |
208 | remove_package_symbol |
209 | /], |
210 | memoize => { |
211 | class_precedence_list => 'ARRAY', |
212 | compute_all_applicable_attributes => 'ARRAY', |
213 | get_meta_instance => 'SCALAR', |
214 | get_method_map => 'SCALAR', |
215 | } |
216 | }); |
217 | |
218 | $immutable_metaclass->make_metaclass_immutable(@_) |
219 | |
c23184fc |
220 | =head1 DESCRIPTION |
221 | |
96e38ba6 |
222 | This is basically a module for applying a transformation on a given |
223 | metaclass. Current features include making methods read-only, |
224 | making methods un-callable and memoizing methods (in a type specific |
225 | way too). |
226 | |
227 | This module is fairly new to the MOP, and quite possibly will be |
228 | expanded and further generalized as the need arises. |
229 | |
c23184fc |
230 | =head1 METHODS |
231 | |
232 | =over 4 |
233 | |
96e38ba6 |
234 | =item B<new ($metaclass, \%options)> |
235 | |
236 | Given a C<$metaclass> and a set of C<%options> this module will |
237 | prepare an immutable version of the C<$metaclass>, which can then |
238 | be applied to the C<$metaclass> using the C<make_metaclass_immutable> |
239 | method. |
240 | |
c23184fc |
241 | =item B<options> |
242 | |
96e38ba6 |
243 | Returns the options HASH set in C<new>. |
244 | |
c23184fc |
245 | =item B<metaclass> |
246 | |
96e38ba6 |
247 | Returns the metaclass set in C<new>. |
248 | |
c23184fc |
249 | =item B<immutable_metaclass> |
250 | |
96e38ba6 |
251 | Returns the immutable metaclass created within C<new>. |
252 | |
c23184fc |
253 | =back |
254 | |
255 | =over 4 |
256 | |
257 | =item B<create_immutable_metaclass> |
258 | |
96e38ba6 |
259 | This will create the immutable version of the C<$metaclass>, but will |
260 | not actually change the original metaclass. |
261 | |
c23184fc |
262 | =item B<create_methods_for_immutable_metaclass> |
263 | |
96e38ba6 |
264 | This will create all the methods for the immutable metaclass based |
265 | on the C<%options> passed into C<new>. |
266 | |
c23184fc |
267 | =item B<make_metaclass_immutable> |
268 | |
96e38ba6 |
269 | This will actually change the C<$metaclass> into the immutable version. |
270 | |
c23184fc |
271 | =back |
272 | |
273 | =head1 AUTHORS |
274 | |
275 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
276 | |
277 | =head1 COPYRIGHT AND LICENSE |
278 | |
2367814a |
279 | Copyright 2006, 2007 by Infinity Interactive, Inc. |
c23184fc |
280 | |
281 | L<http://www.iinteractive.com> |
282 | |
283 | This library is free software; you can redistribute it and/or modify |
284 | it under the same terms as Perl itself. |
285 | |
286 | =cut |