our $VERSION = '0.01';
+# Self-introspection
+
+sub meta { $_[0]->initialize($_[0]) }
+
# Creation
{
sub initialize {
my ($class, $package_name) = @_;
(defined $package_name && $package_name)
- || confess "You must pass a package name";
- $METAS{$package_name} ||= bless \$package_name => blessed($class) || $class;
+ || confess "You must pass a package name";
+ return $METAS{$package_name} if exists $METAS{$package_name};
+ $METAS{$package_name} = $class->construct_class_instance($package_name);
+ }
+
+ # NOTE: (meta-circularity)
+ # this is a special form of &construct_instance
+ # (see below), which is used to construct class
+ # meta-object instances for any Class::MOP::*
+ # class. All other classes will use the more
+ # normal &construct_instance.
+ sub construct_class_instance {
+ my ($class, $package_name) = @_;
+ (defined $package_name && $package_name)
+ || confess "You must pass a package name";
+ $class = blessed($class) || $class;
+ if ($class =~ /^Class::MOP::/) {
+ bless {
+ '$:pkg' => $package_name,
+ '%:attrs' => {}
+ } => $class;
+ }
+ else {
+ bless $class->meta->construct_instance(':pkg' => $package_name) => $class
+ }
}
}
my $meta = $class->initialize($package_name);
$meta->superclasses(@{$options{superclasses}})
if exists $options{superclasses};
+ # NOTE:
+ # process attributes first, so that they can
+ # install accessors, but locally defined methods
+ # can then overwrite them. It is maybe a little odd, but
+ # I think this should be the order of things.
+ if (exists $options{attributes}) {
+ foreach my $attr (@{$options{attributes}}) {
+ $meta->add_attribute($attr);
+ }
+ }
if (exists $options{methods}) {
foreach my $method_name (keys %{$options{methods}}) {
$meta->add_method($method_name, $options{methods}->{$method_name});
}
- }
+ }
return $meta;
}
+# Instance Construction
+
+sub construct_instance {
+ my ($class, %params) = @_;
+ my $instance = {};
+ foreach my $attr (map { $_->{attribute} } $class->compute_all_applicable_attributes()) {
+ # 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 = $params{$init_arg} if exists $params{$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
+ $instance->{$attr->name} = $val;
+ }
+ return $instance;
+}
+
# Informational
-sub name { ${$_[0]} }
+sub name { $_[0]->{'$:pkg'} }
sub version {
my $self = shift;
{
## private utility functions for has_method
- my $_find_subroutine_package_name = sub { eval { svref_2object($_[0])->GV->STASH->NAME } };
- my $_find_subroutine_name = sub { eval { svref_2object($_[0])->GV->NAME } };
+ my $_find_subroutine_package_name = sub { eval { svref_2object($_[0])->GV->STASH->NAME } || '' };
+ my $_find_subroutine_name = sub { eval { svref_2object($_[0])->GV->NAME } || '' };
sub has_method {
my ($self, $method_name) = @_;
return @methods;
}
-## Recursive Version of compute_all_applicable_methods
-# sub compute_all_applicable_methods {
-# my ($self, $seen) = @_;
-# $seen ||= {};
-# (
-# (map {
-# if (exists $seen->{$_}) {
-# ();
-# }
-# else {
-# $seen->{$_}++;
-# {
-# name => $_,
-# class => $self->name,
-# code => $self->get_method($_)
-# };
-# }
-# } $self->get_method_list()),
-# map {
-# $self->initialize($_)->compute_all_applicable_methods($seen)
-# } $self->superclasses()
-# );
-# }
-
sub find_all_methods_by_name {
my ($self, $method_name) = @_;
(defined $method_name && $method_name)
## Attributes
-sub has_attribute {}
-sub get_attribute {}
-sub add_attribute {}
-sub remove_attribute {}
-sub get_attribute_list {}
-sub compute_all_applicable_attributes {}
-sub create_all_accessors {}
+sub add_attribute {
+ my ($self,$attribute) = @_;
+ (blessed($attribute) && $attribute->isa('Class::MOP::Attribute'))
+ || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
+ $attribute->install_accessors($self);
+ $self->{'%:attrs'}->{$attribute->name} = $attribute;
+}
+
+sub has_attribute {
+ my ($self, $attribute_name) = @_;
+ (defined $attribute_name && $attribute_name)
+ || confess "You must define an attribute name";
+ exists $self->{'%:attrs'}->{$attribute_name} ? 1 : 0;
+}
+
+sub get_attribute {
+ my ($self, $attribute_name) = @_;
+ (defined $attribute_name && $attribute_name)
+ || confess "You must define an attribute name";
+ return $self->{'%:attrs'}->{$attribute_name}
+ if $self->has_attribute($attribute_name);
+}
+
+sub remove_attribute {
+ my ($self, $attribute_name) = @_;
+ (defined $attribute_name && $attribute_name)
+ || confess "You must define an attribute name";
+ my $removed_attribute = $self->{'%:attrs'}->{$attribute_name};
+ delete $self->{'%:attrs'}->{$attribute_name}
+ if defined $removed_attribute;
+ $removed_attribute->remove_accessors($self);
+ return $removed_attribute;
+}
+
+sub get_attribute_list {
+ my $self = shift;
+ keys %{$self->{'%:attrs'}};
+}
+
+sub compute_all_applicable_attributes {
+ my $self = shift;
+ my @attrs;
+ # keep a record of what we have seen
+ # here, this will handle all the
+ # inheritence issues because we are
+ # using the &class_precedence_list
+ my (%seen_class, %seen_attr);
+ foreach my $class ($self->class_precedence_list()) {
+ next if $seen_class{$class};
+ $seen_class{$class}++;
+ # fetch the meta-class ...
+ my $meta = $self->initialize($class);
+ foreach my $attr_name ($meta->get_attribute_list()) {
+ next if exists $seen_attr{$attr_name};
+ $seen_attr{$attr_name}++;
+ push @attrs => {
+ name => $attr_name,
+ class => $class,
+ attribute => $meta->get_attribute($attr_name)
+ };
+ }
+ }
+ return @attrs;
+}
1;
=head1 SYNOPSIS
+ # use this for introspection ...
+
+ package Foo;
+ sub meta { Class::MOP::Class->initialize(__PACKAGE__) }
+
+ # elsewhere in the code ...
+
+ # add a method to Foo ...
+ Foo->meta->add_method('bar' => sub { ... })
+
+ # get a list of all the classes searched
+ # the method dispatcher in the correct order
+ Foo->meta->class_precedence_list()
+
+ # remove a method from Foo
+ Foo->meta->remove_method('bar');
+
+ # or use this to actually create classes ...
+
+ Class::MOP::Class->create('Bar' => '0.01' => (
+ superclasses => [ 'Foo' ],
+ attributes => [
+ Class::MOP:::Attribute->new('$bar'),
+ Class::MOP:::Attribute->new('$baz'),
+ ],
+ methods => {
+ calculate_bar => sub { ... },
+ construct_baz => sub { ... }
+ }
+ ));
+
=head1 DESCRIPTION
+This is the largest and currently most complex part of the Perl 5
+meta-object protocol. It controls the introspection and
+manipulation of Perl 5 classes (and it can create them too). The
+best way to understand what this module can do, is to read the
+documentation for each of it's methods.
+
=head1 METHODS
+=head2 Self Introspection
+
+=over 4
+
+=item B<meta>
+
+This will return a B<Class::MOP::Class> instance which is related
+to this class. Thereby allowing B<Class::MOP::Class> to actually
+introspect itself.
+
+As with B<Class::MOP::Attribute>, B<Class::MOP> will actually
+bootstrap this module by installing a number of attribute meta-objects
+into it's metaclass. This will allow this class to reap all the benifits
+of the MOP when subclassing it.
+
+=back
+
=head2 Class construction
These methods handle creating Class objects, which can be used to
=over 4
-=item B<construct_instance ($canidate, %params)>
+=item B<construct_instance (%params)>
-This will construct and instance using the C<$canidate> as storage
+This will construct and instance using a HASH ref as storage
(currently only HASH references are supported). This will collect all
the applicable attribute meta-objects and layout out the fields in the
-C<$canidate>, it will then initialize them using either use the
+HASH ref, it will then initialize them using either use the
corresponding key in C<%params> or any default value or initializer
found in the attribute meta-object.
+=item B<construct_class_instance ($package_name)>
+
+This will construct an instance of B<Class::MOP::Class>, it is
+here so that we can actually "tie the knot" for B<Class::MOP::Class>
+to use C<construct_instance> once all the bootstrapping is done. This
+method is used internally by C<initialize> and should never be called
+from outside of that method really.
+
=back
=head2 Informational
references for all the applicable attributes for this class. The HASH
references will contain the following information; the attribute name,
the class which the attribute is associated with and the actual
-attribute meta-object
-
-=item B<create_all_accessors>
-
-This will communicate with all of the classes attributes to create
-and install the appropriate accessors. (see L<The Attribute Protocol>
-below for more details).
+attribute meta-object.
=back
projects / gitmo/Class-MOP.git / blobdiff