2 package Class::MOP::Immutable;
7 use Class::MOP::Method::Constructor;
10 use Scalar::Util 'blessed';
12 our $VERSION = '0.01';
13 our $AUTHORITY = 'cpan:STEVAN';
16 my ($class, $metaclass, $options) = @_;
19 '$!metaclass' => $metaclass,
20 '%!options' => $options,
21 '$!immutable_metaclass' => undef,
25 # we initialize the immutable
26 # version of the metaclass here
27 $self->create_immutable_metaclass;
32 sub immutable_metaclass { (shift)->{'$!immutable_metaclass'} }
33 sub metaclass { (shift)->{'$!metaclass'} }
34 sub options { (shift)->{'%!options'} }
36 sub create_immutable_metaclass {
40 # The immutable version of the
41 # metaclass is just a anon-class
42 # which shadows the methods
44 $self->{'$!immutable_metaclass'} = Class::MOP::Class->create_anon_class(
45 superclasses => [ blessed($self->metaclass) ],
46 methods => $self->create_methods_for_immutable_metaclass,
50 my %DEFAULT_METHODS = (
53 # if it is not blessed, then someone is asking
54 # for the meta of Class::MOP::Class::Immutable
55 return Class::MOP::Class->initialize($self) unless blessed($self);
56 # otherwise, they are asking for the metaclass
57 # which has been made immutable, which is itself
60 is_mutable => sub { 0 },
61 is_immutable => sub { 1 },
62 make_immutable => sub { ( ) },
66 # this will actually convert the
67 # existing metaclass to an immutable
69 sub make_metaclass_immutable {
70 my ($self, $metaclass, %options) = @_;
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 $options{debug};
78 if ($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);
86 if ($options{inline_constructor}) {
87 my $constructor_class = $options{constructor_class} || 'Class::MOP::Method::Constructor';
89 $metaclass->add_method(
90 $options{constructor_name},
91 $constructor_class->new(
93 metaclass => $metaclass,
95 ) unless $metaclass->has_method($options{constructor_name});
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";
103 my $destructor_class = $options{destructor_class};
105 my $destructor = $destructor_class->new(
106 options => \%options,
107 metaclass => $metaclass,
110 $metaclass->add_method('DESTROY' => $destructor)
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
116 if $destructor->is_needed;
119 my $memoized_methods = $self->options->{memoize};
120 foreach my $method_name (keys %{$memoized_methods}) {
121 my $type = $memoized_methods->{$method_name};
123 ($metaclass->can($method_name))
124 || confess "Could not find the method '$method_name' in " . $metaclass->name;
126 if ($type eq 'ARRAY') {
127 $metaclass->{'___' . $method_name} = [ $metaclass->$method_name ];
129 elsif ($type eq 'HASH') {
130 $metaclass->{'___' . $method_name} = { $metaclass->$method_name };
132 elsif ($type eq 'SCALAR') {
133 $metaclass->{'___' . $method_name} = $metaclass->$method_name;
137 #I'm not sure i understand this, stevan suggested the addition i don't think its actually needed
138 #my $is_immutable = $metaclass->is_anon_class;
139 #$self->immutable_metaclass->add_method('is_anon_class' => sub { $is_immutable });
141 $metaclass->{'___original_class'} = blessed($metaclass);
142 bless $metaclass => $self->immutable_metaclass->name;
145 sub make_metaclass_mutable {
146 my ($self, $immutable, %options) = @_;
148 my $original_class = $immutable->get_mutable_metaclass_name;
149 delete $immutable->{'___original_class'} ;
150 bless $immutable => $original_class;
152 my $memoized_methods = $self->options->{memoize};
153 foreach my $method_name (keys %{$memoized_methods}) {
154 my $type = $memoized_methods->{$method_name};
156 ($immutable->can($method_name))
157 || confess "Could not find the method '$method_name' in " . $immutable->name;
158 if ($type eq 'SCALAR' || $type eq 'ARRAY' || $type eq 'HASH' ) {
159 delete $immutable->{'___' . $method_name};
163 if ($options{inline_destructor} && $immutable->has_method('DESTROY')) {
164 $immutable->remove_method('DESTROY')
165 if $immutable->get_method('DESTROY')->blessed eq $options{destructor_class};
168 #14:01 <@stevan> nah,. you shouldnt
169 #14:01 <@stevan> they are just inlined
170 #14:01 <@stevan> which is the default in Moose anyway
171 #14:02 <@stevan> and adding new attributes will just DWIM
172 #14:02 <@stevan> and you really cant change an attribute anyway
173 #if ($options{inline_accessors}) {
174 # foreach my $attr_name ($immutable->get_attribute_list) {
175 # my $attr = $immutable->get_attribute($attr_name);
176 # $attr->remove_accessors;
177 # $attr->install_accessors(0);
181 #14:26 <@stevan> the only user of ::Method::Constructor is immutable
182 #14:27 <@stevan> if someone uses it outside of immutable,.. they are either: mst or groditi
183 #14:27 <@stevan> so I am not worried
184 $options{constructor_name} = 'new' unless exists $options{constructor_name};
185 if ($options{inline_constructor}) {
186 my $constructor_class = $options{constructor_class} || 'Class::MOP::Method::Constructor';
187 $immutable->remove_method( $options{constructor_name} )
188 if $immutable->get_method($options{constructor_name})->blessed eq $constructor_class;
192 sub create_methods_for_immutable_metaclass {
195 my %methods = %DEFAULT_METHODS;
197 foreach my $read_only_method (@{$self->options->{read_only}}) {
198 my $method = $self->metaclass->meta->find_method_by_name($read_only_method);
201 || confess "Could not find the method '$read_only_method' in " . $self->metaclass->name;
203 $methods{$read_only_method} = sub {
204 confess "This method is read-only" if scalar @_ > 1;
205 goto &{$method->body}
209 foreach my $cannot_call_method (@{$self->options->{cannot_call}}) {
210 $methods{$cannot_call_method} = sub {
211 confess "This method ($cannot_call_method) cannot be called on an immutable instance";
215 my $memoized_methods = $self->options->{memoize};
216 foreach my $method_name (keys %{$memoized_methods}) {
217 my $type = $memoized_methods->{$method_name};
218 if ($type eq 'ARRAY') {
219 $methods{$method_name} = sub { @{$_[0]->{'___' . $method_name}} };
221 elsif ($type eq 'HASH') {
222 $methods{$method_name} = sub { %{$_[0]->{'___' . $method_name}} };
224 elsif ($type eq 'SCALAR') {
225 $methods{$method_name} = sub { $_[0]->{'___' . $method_name} };
229 $methods{get_mutable_metaclass_name} = sub { (shift)->{'___original_class'} };
242 Class::MOP::Immutable - A class to transform Class::MOP::Class metaclasses
246 use Class::MOP::Immutable;
248 my $immutable_metaclass = Class::MOP::Immutable->new($metaclass, {
249 read_only => [qw/superclasses/],
257 remove_package_symbol
260 class_precedence_list => 'ARRAY',
261 compute_all_applicable_attributes => 'ARRAY',
262 get_meta_instance => 'SCALAR',
263 get_method_map => 'SCALAR',
267 $immutable_metaclass->make_metaclass_immutable(@_)
271 This is basically a module for applying a transformation on a given
272 metaclass. Current features include making methods read-only,
273 making methods un-callable and memoizing methods (in a type specific
276 This module is fairly new to the MOP, and quite possibly will be
277 expanded and further generalized as the need arises.
283 =item B<new ($metaclass, \%options)>
285 Given a C<$metaclass> and a set of C<%options> this module will
286 prepare an immutable version of the C<$metaclass>, which can then
287 be applied to the C<$metaclass> using the C<make_metaclass_immutable>
292 Returns the options HASH set in C<new>.
296 Returns the metaclass set in C<new>.
298 =item B<immutable_metaclass>
300 Returns the immutable metaclass created within C<new>.
306 =item B<create_immutable_metaclass>
308 This will create the immutable version of the C<$metaclass>, but will
309 not actually change the original metaclass.
311 =item B<create_methods_for_immutable_metaclass>
313 This will create all the methods for the immutable metaclass based
314 on the C<%options> passed into C<new>.
316 =item B<make_metaclass_immutable (%options)>
318 This will actually change the C<$metaclass> into the immutable version.
320 =item B<make_metaclass_mutable (%options)>
322 This will change the C<$metaclass> into the mutable version by reversing
323 the immutable process. C<%options> should be the same options that were
324 given to make_metaclass_immutable.
330 Stevan Little E<lt>stevan@iinteractive.comE<gt>
332 =head1 COPYRIGHT AND LICENSE
334 Copyright 2006, 2007 by Infinity Interactive, Inc.
336 L<http://www.iinteractive.com>
338 This library is free software; you can redistribute it and/or modify
339 it under the same terms as Perl itself.