use strict;
use warnings;
-use Class::MOP 'meta';
-
-our $VERSION = '0.01';
+our $VERSION = '0.06';
use base 'Class::MOP::Class';
+sub initialize {
+ (shift)->SUPER::initialize(@_,
+ # use the custom attribute metaclass here
+ 'attribute_metaclass' => 'ClassEncapsulatedAttributes::Attribute',
+ );
+}
+
sub construct_instance {
my ($class, %params) = @_;
- #use Data::Dumper; warn Dumper \%params;
- my $instance = {};
+
+ my $meta_instance = $class->get_meta_instance;
+ my $instance = $meta_instance->create_instance();
+
+ # initialize *ALL* attributes, including masked ones (as opposed to applicable)
foreach my $current_class ($class->class_precedence_list()) {
- $instance->{$current_class} = {}
- unless exists $instance->{$current_class};
- my $meta = $class->initialize($current_class);
+ my $meta = $current_class->meta;
foreach my $attr_name ($meta->get_attribute_list()) {
my $attr = $meta->get_attribute($attr_name);
- # if the attr has an init_arg, use that, otherwise,
- # use the attributes name itself as the init_arg
- my $init_arg = $attr->has_init_arg() ? $attr->init_arg() : $attr->name;
- # try to fetch the init arg from the %params ...
- my $val;
- $val = $params{$current_class}->{$init_arg}
- if exists $params{$current_class} &&
- exists ${$params{$current_class}}{$init_arg};
- # if nothing was in the %params, we can use the
- # attribute's default value (if it has one)
- $val ||= $attr->default($instance) if $attr->has_default();
- # now add this to the instance structure
- $instance->{$current_class}->{$attr_name} = $val;
+ $attr->initialize_instance_slot($meta_instance, $instance, \%params);
}
}
- #use Data::Dumper; warn Dumper $instance;
- return $instance;
+
+ return $instance;
}
package # hide the package from PAUSE
use strict;
use warnings;
-use Class::MOP 'meta';
-
-our $VERSION = '0.01';
+our $VERSION = '0.04';
use base 'Class::MOP::Attribute';
-sub generate_accessor_method {
- my ($self, $attr_name) = @_;
- my $class_name = $self->associated_class->name;
- eval qq{sub {
- \$_[0]->{'$class_name'}->{'$attr_name'} = \$_[1] if scalar(\@_) == 2;
- \$_[0]->{'$class_name'}->{'$attr_name'};
- }};
-}
-
-sub generate_reader_method {
- my ($self, $attr_name) = @_;
- my $class_name = $self->associated_class->name;
- eval qq{sub {
- \$_[0]->{'$class_name'}->{'$attr_name'};
- }};
-}
-
-sub generate_writer_method {
- my ($self, $attr_name) = @_;
- my $class_name = $self->associated_class->name;
- eval qq{sub {
- \$_[0]->{'$class_name'}->{'$attr_name'} = \$_[1];
- }};
+# alter the way parameters are specified
+sub initialize_instance_slot {
+ my ($self, $meta_instance, $instance, $params) = @_;
+ # if the attr has an init_arg, use that, otherwise,
+ # use the attributes name itself as the init_arg
+ my $init_arg = $self->init_arg();
+ # try to fetch the init arg from the %params ...
+ my $class = $self->associated_class;
+ my $val;
+ $val = $params->{$class->name}->{$init_arg}
+ if exists $params->{$class->name} &&
+ exists ${$params->{$class->name}}{$init_arg};
+ # if nothing was in the %params, we can use the
+ # attribute's default value (if it has one)
+ if (!defined $val && $self->has_default) {
+ $val = $self->default($instance);
+ }
+
+ # now add this to the instance structure
+ $meta_instance->set_slot_value($instance, $self->name, $val);
}
-sub generate_predicate_method {
- my ($self, $attr_name) = @_;
- my $class_name = $self->associated_class->name;
- eval qq{sub {
- defined \$_[0]->{'$class_name'}->{'$attr_name'} ? 1 : 0;
- }};
+sub name {
+ my $self = shift;
+ return ($self->associated_class->name . '::' . $self->SUPER::name)
}
-## &remove_attribute is left as an exercise for the reader :)
-
1;
__END__
package Foo;
- sub meta { ClassEncapsulatedAttributes->initialize($_[0]) }
+ use metaclass 'ClassEncapsulatedAttributes';
- Foo->meta->add_attribute(
- ClassEncapsulatedAttributes::Attribute->new('foo' => (
- accessor => 'Foo_foo',
- default => 'init in FOO'
- ))
- );
+ Foo->meta->add_attribute('foo' => (
+ accessor => 'Foo_foo',
+ default => 'init in FOO'
+ ));
sub new {
my $class = shift;
- bless $class->meta->construct_instance(@_) => $class;
+ $class->meta->new_object(@_);
}
package Bar;
our @ISA = ('Foo');
# duplicate the attribute name here
- Bar->meta->add_attribute(
- ClassEncapsulatedAttributes::Attribute->new('foo' => (
- accessor => 'Bar_foo',
- default => 'init in BAR'
- ))
- );
+ Bar->meta->add_attribute('foo' => (
+ accessor => 'Bar_foo',
+ default => 'init in BAR'
+ ));
# ... later in other code ...
=head1 DESCRIPTION
-=head1 AUTHOR
+This is an example metaclass which encapsulates a class's
+attributes on a per-class basis. This means that there is no
+possibility of name clashes with inherited attributes. This
+is similar to how C++ handles its data members.
+
+=head1 ACKNOWLEDGEMENTS
+
+Thanks to Yuval "nothingmuch" Kogman for the idea for this example.
+
+=head1 AUTHORS
Stevan Little E<lt>stevan@iinteractive.comE<gt>
+Yuval Kogman E<lt>nothingmuch@woobling.comE<gt>
+
=head1 COPYRIGHT AND LICENSE
-Copyright 2006 by Infinity Interactive, Inc.
+Copyright 2006-2008 by Infinity Interactive, Inc.
L<http://www.iinteractive.com>
projects / gitmo/Class-MOP.git / blobdiff