use Scalar::Util 'blessed', 'reftype';
use Sub::Name 'subname';
use B 'svref_2object';
+use Clone ();
-our $VERSION = '0.01';
+our $VERSION = '0.03';
# Self-introspection
-sub meta { $_[0]->initialize($_[0]) }
+sub meta { Class::MOP::Class->initialize($_[0]) }
# Creation
# there is no need to worry about destruction though
# because they should die only when the program dies.
# After all, do package definitions even get reaped?
- my %METAS;
+ my %METAS;
+
sub initialize {
- my ($class, $package_name) = @_;
+ my $class = shift;
+ my $package_name = shift;
(defined $package_name && $package_name)
- || 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);
+ || confess "You must pass a package name";
+ # make sure the package name is not blessed
+ $package_name = blessed($package_name) || $package_name;
+ $class->construct_class_instance(':package' => $package_name, @_);
}
# NOTE: (meta-circularity)
# class. All other classes will use the more
# normal &construct_instance.
sub construct_class_instance {
- my ($class, $package_name) = @_;
+ my $class = shift;
+ my %options = @_;
+ my $package_name = $options{':package'};
(defined $package_name && $package_name)
- || confess "You must pass a package name";
+ || confess "You must pass a package name";
+ return $METAS{$package_name} if exists $METAS{$package_name};
$class = blessed($class) || $class;
+ # now create the metaclass
+ my $meta;
if ($class =~ /^Class::MOP::/) {
- bless {
- '$:pkg' => $package_name,
- '%:attrs' => {}
+ $meta = bless {
+ '$:package' => $package_name,
+ '%:attributes' => {},
+ '$:attribute_metaclass' => $options{':attribute_metaclass'} || 'Class::MOP::Attribute',
+ '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method',
} => $class;
}
else {
- bless $class->meta->construct_instance(':pkg' => $package_name) => $class
+ # NOTE:
+ # it is safe to use meta here because
+ # class will always be a subclass of
+ # Class::MOP::Class, which defines meta
+ $meta = bless $class->meta->construct_instance(%options) => $class
}
+ # and check the metaclass compatibility
+ $meta->check_metaclass_compatability();
+ $METAS{$package_name} = $meta;
+ }
+
+ sub check_metaclass_compatability {
+ my $self = shift;
+
+ # this is always okay ...
+ return if blessed($self) eq 'Class::MOP::Class';
+
+ my @class_list = $self->class_precedence_list;
+ shift @class_list; # shift off $self->name
+
+ foreach my $class_name (@class_list) {
+ next unless $METAS{$class_name};
+ my $meta = $METAS{$class_name};
+ ($self->isa(blessed($meta)))
+ || confess $self->name . "->meta => (" . (blessed($self)) . ")" .
+ " is not compatible with the " .
+ $class_name . "->meta => (" . (blessed($meta)) . ")";
+ }
}
}
return $meta;
}
-# Instance Construction
+## Attribute readers
+
+# NOTE:
+# all these attribute readers will be bootstrapped
+# away in the Class::MOP bootstrap section
+
+sub name { $_[0]->{'$:package'} }
+sub get_attribute_map { $_[0]->{'%:attributes'} }
+sub attribute_metaclass { $_[0]->{'$:attribute_metaclass'} }
+sub method_metaclass { $_[0]->{'$:method_metaclass'} }
+
+# Instance Construction & Cloning
+
+sub new_object {
+ my $class = shift;
+ # NOTE:
+ # we need to protect the integrity of the
+ # Class::MOP::Class singletons here, so we
+ # delegate this to &construct_class_instance
+ # which will deal with the singletons
+ return $class->construct_class_instance(@_)
+ if $class->name->isa('Class::MOP::Class');
+ bless $class->construct_instance(@_) => $class->name;
+}
sub construct_instance {
my ($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;
+ foreach my $attr ($class->compute_all_applicable_attributes()) {
+ my $init_arg = $attr->init_arg();
# 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
+ $val ||= $attr->default($instance) if $attr->has_default();
$instance->{$attr->name} = $val;
}
return $instance;
}
+sub clone_object {
+ my $class = shift;
+ my $instance = shift;
+ (blessed($instance) && $instance->isa($class->name))
+ || confess "You must pass an instance ($instance) of the metaclass (" . $class->name . ")";
+ # NOTE:
+ # we need to protect the integrity of the
+ # Class::MOP::Class singletons here, they
+ # should not be cloned.
+ return $instance if $instance->isa('Class::MOP::Class');
+ bless $class->clone_instance($instance, @_) => blessed($instance);
+}
+
+sub clone_instance {
+ my ($class, $instance, %params) = @_;
+ (blessed($instance))
+ || confess "You can only clone instances, \$self is not a blessed instance";
+ # NOTE:
+ # This will deep clone, which might
+ # not be what you always want. So
+ # the best thing is to write a more
+ # controled &clone method locally
+ # in the class (see Class::MOP)
+ my $clone = Clone::clone($instance);
+ foreach my $attr ($class->compute_all_applicable_attributes()) {
+ my $init_arg = $attr->init_arg();
+ # try to fetch the init arg from the %params ...
+ $clone->{$attr->name} = $params{$init_arg}
+ if exists $params{$init_arg};
+ }
+ return $clone;
+}
+
# Informational
-sub name { $_[0]->{'$:pkg'} }
+# &name should be here too, but it is above
+# because it gets bootstrapped away
sub version {
my $self = shift;
## Attributes
sub add_attribute {
- my ($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;
+ my $self = shift;
+ # either we have an attribute object already
+ # or we need to create one from the args provided
+ my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
+ # make sure it is derived from the correct type though
+ ($attribute->isa('Class::MOP::Attribute'))
+ || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
+ $attribute->attach_to_class($self);
+ $attribute->install_accessors();
+ $self->get_attribute_map->{$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;
+ exists $self->get_attribute_map->{$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}
+ return $self->get_attribute_map->{$attribute_name}
if $self->has_attribute($attribute_name);
}
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);
+ my $removed_attribute = $self->get_attribute_map->{$attribute_name};
+ delete $self->get_attribute_map->{$attribute_name}
+ if defined $removed_attribute;
+ $removed_attribute->remove_accessors();
+ $removed_attribute->detach_from_class();
return $removed_attribute;
}
sub get_attribute_list {
my $self = shift;
- keys %{$self->{'%:attrs'}};
+ keys %{$self->get_attribute_map};
}
sub compute_all_applicable_attributes {
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)
- };
+ push @attrs => $meta->get_attribute($attr_name);
}
}
return @attrs;
=head2 Class construction
-These methods handle creating Class objects, which can be used to
-both create new classes, and analyze pre-existing ones.
+These methods will handle creating B<Class::MOP::Class> objects,
+which can be used to both create new classes, and analyze
+pre-existing classes.
This module will internally store references to all the instances
you create with these methods, so that they do not need to be
=over 4
=item B<create ($package_name, ?$package_version,
- superclasses => ?@superclasses,
- methods => ?%methods,
- attributes => ?%attributes)>
+ superclasses =E<gt> ?@superclasses,
+ methods =E<gt> ?%methods,
+ attributes =E<gt> ?%attributes)>
-This returns the basic Class object, bringing the specified
+This returns a B<Class::MOP::Class> object, bringing the specified
C<$package_name> into existence and adding any of the
C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes>
to it.
=item B<initialize ($package_name)>
-This initializes a Class object for a given a C<$package_name>.
+This initializes and returns returns a B<Class::MOP::Class> object
+for a given a C<$package_name>.
+
+=item B<construct_class_instance (%options)>
+
+This will construct an instance of B<Class::MOP::Class>, it is
+here so that we can actually "tie the knot" for B<Class::MOP::Class>
+to use C<construct_instance> once all the bootstrapping is done. This
+method is used internally by C<initialize> and should never be called
+from outside of that method really.
+
+=item B<check_metaclass_compatability>
+
+This method is called as the very last thing in the
+C<construct_class_instance> method. This will check that the
+metaclass you are creating is compatible with the metaclasses of all
+your ancestors. For more inforamtion about metaclass compatibility
+see the C<About Metaclass compatibility> section in L<Class::MOP>.
=back
-=head2 Instance construction
+=head2 Object instance construction and cloning
+
+These methods are B<entirely optional>, it is up to you whether you want
+to use them or not.
=over 4
+=item B<new_object (%params)>
+
+This is a convience method for creating a new object of the class, and
+blessing it into the appropriate package as well. Ideally your class
+would call a C<new> this method like so:
+
+ sub MyClass::new {
+ my ($class, %param) = @_;
+ $class->meta->new_object(%params);
+ }
+
+Of course the ideal place for this would actually be in C<UNIVERSAL::>
+but that is considered bad style, so we do not do that.
+
=item B<construct_instance (%params)>
+This method is used to construct an instace structure suitable for
+C<bless>-ing into your package of choice. It works in conjunction
+with the Attribute protocol to collect all applicable attributes.
+
This will construct and instance using a HASH ref as storage
(currently only HASH references are supported). This will collect all
-the applicable attribute meta-objects and layout out the fields in the
-HASH ref, it will then initialize them using either use the
-corresponding key in C<%params> or any default value or initializer
-found in the attribute meta-object.
+the applicable attributes and layout out the fields in the HASH ref,
+it will then initialize them using either use the corresponding key
+in C<%params> or any default value or initializer found in the
+attribute meta-object.
-=item B<construct_class_instance ($package_name)>
+=item B<clone_object ($instance, %params)>
-This will construct an instance of B<Class::MOP::Class>, it is
-here so that we can actually "tie the knot" for B<Class::MOP::Class>
-to use C<construct_instance> once all the bootstrapping is done. This
-method is used internally by C<initialize> and should never be called
-from outside of that method really.
+This is a convience method for cloning an object instance, then
+blessing it into the appropriate package. Ideally your class
+would call a C<clone> this method like so:
+
+ sub MyClass::clone {
+ my ($self, %param) = @_;
+ $self->meta->clone_object($self, %params);
+ }
+
+Of course the ideal place for this would actually be in C<UNIVERSAL::>
+but that is considered bad style, so we do not do that.
+
+=item B<clone_instance($instance, %params)>
+
+This method is a compliment of C<construct_instance> (which means if
+you override C<construct_instance>, you need to override this one too).
+
+This method will clone the C<$instance> structure created by the
+C<construct_instance> method, and apply any C<%params> passed to it
+to change the attribute values. The structure returned is (like with
+C<construct_instance>) an unC<bless>ed HASH reference, it is your
+responsibility to then bless this cloned structure into the right
+class.
=back
=item B<name>
-This is a read-only attribute which returns the package name that
-the Class is stored in.
+This is a read-only attribute which returns the package name for the
+given B<Class::MOP::Class> instance.
=item B<version>
This is a read-only attribute which returns the C<$VERSION> of the
-package the Class is stored in.
+package for the given B<Class::MOP::Class> instance.
=back
=item B<superclasses (?@superclasses)>
This is a read-write attribute which represents the superclass
-relationships of this Class. Basically, it can get and set the
-C<@ISA> for you.
+relationships of the class the B<Class::MOP::Class> instance is
+associated with. Basically, it can get and set the C<@ISA> for you.
+
+B<NOTE:>
+Perl will occasionally perform some C<@ISA> and method caching, if
+you decide to change your superclass relationship at runtime (which
+is quite insane and very much not recommened), then you should be
+aware of this and the fact that this module does not make any
+attempt to address this issue.
=item B<class_precedence_list>
-This computes the a list of the Class's ancestors in the same order
-in which method dispatch will be done.
+This computes the a list of all the class's ancestors in the same order
+in which method dispatch will be done. This is similair to
+what B<Class::ISA::super_path> does, but we don't remove duplicate names.
=back
=over 4
+=item B<method_metaclass>
+
=item B<add_method ($method_name, $method)>
This will take a C<$method_name> and CODE reference to that
-C<$method> and install it into the Class.
+C<$method> and install it into the class's package.
-B<NOTE> : This does absolutely nothing special to C<$method>
+B<NOTE>:
+This does absolutely nothing special to C<$method>
other than use B<Sub::Name> to make sure it is tagged with the
correct name, and therefore show up correctly in stack traces and
such.
=item B<has_method ($method_name)>
-This just provides a simple way to check if the Class implements
+This just provides a simple way to check if the class implements
a specific C<$method_name>. It will I<not> however, attempt to check
-if the class inherits the method.
+if the class inherits the method (use C<UNIVERSAL::can> for that).
This will correctly handle functions defined outside of the package
that use a fully qualified name (C<sub Package::name { ... }>).
In short, this method cannot always be trusted to determine if the
C<$method_name> is actually a method. However, it will DWIM about
-90% of the time, so it's a small trade off IMO.
+90% of the time, so it's a small trade off I think.
=item B<get_method ($method_name)>
=item B<remove_method ($method_name)>
-This will attempt to remove a given C<$method_name> from the Class.
+This will attempt to remove a given C<$method_name> from the class.
It will return the CODE reference that it has removed, and will
attempt to use B<Sub::Name> to clear the methods associated name.
=item B<compute_all_applicable_methods>
-This will return a list of all the methods names this Class will
-support, taking into account inheritance. The list will be a list of
+This will return a list of all the methods names this class will
+respond to, taking into account inheritance. The list will be a list of
HASH references, each one containing the following information; method
name, the name of the class in which the method lives and a CODE
reference for the actual method.
It should be noted that since there is no one consistent way to define
the attributes of a class in Perl 5. These methods can only work with
the information given, and can not easily discover information on
-their own.
+their own. See L<Class::MOP::Attribute> for more details.
=over 4
+=item B<attribute_metaclass>
+
+=item B<get_attribute_map>
+
=item B<add_attribute ($attribute_name, $attribute_meta_object)>
-This stores a C<$attribute_meta_object> in the Class object and
-associates it with the C<$attribute_name>. Unlike methods, attributes
-within the MOP are stored as meta-information only. They will be used
-later to construct instances from (see C<construct_instance> above).
+This stores a C<$attribute_meta_object> in the B<Class::MOP::Class>
+instance associated with the given class, and associates it with
+the C<$attribute_name>. Unlike methods, attributes within the MOP
+are stored as meta-information only. They will be used later to
+construct instances from (see C<construct_instance> above).
More details about the attribute meta-objects can be found in the
-L<The Attribute protocol> section of this document.
+L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol>
+section.
+
+It should be noted that any accessor, reader/writer or predicate
+methods which the C<$attribute_meta_object> has will be installed
+into the class at this time.
=item B<has_attribute ($attribute_name)>
-Checks to see if this Class has an attribute by the name of
+Checks to see if this class has an attribute by the name of
C<$attribute_name> and returns a boolean.
=item B<get_attribute ($attribute_name)>
This will remove the attribute meta-object stored at
C<$attribute_name>, then return the removed attribute meta-object.
-B<NOTE:> Removing an attribute will only affect future instances of
+B<NOTE:>
+Removing an attribute will only affect future instances of
the class, it will not make any attempt to remove the attribute from
any existing instances of the class.
+It should be noted that any accessor, reader/writer or predicate
+methods which the attribute meta-object stored at C<$attribute_name>
+has will be removed from the class at this time. This B<will> make
+these attributes somewhat inaccessable in previously created
+instances. But if you are crazy enough to do this at runtime, then
+you are crazy enough to deal with something like this :).
+
=item B<get_attribute_list>
This returns a list of attribute names which are defined in the local
=item B<compute_all_applicable_attributes>
-This will traverse the inheritance heirachy and return a list of HASH
-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.
+This will traverse the inheritance heirachy and return a list of all
+the applicable attributes for this class. It does not construct a
+HASH reference like C<compute_all_applicable_methods> because all
+that same information is discoverable through the attribute
+meta-object itself.
=back
=head1 AUTHOR
-Stevan Little E<gt>stevan@iinteractive.comE<lt>
+Stevan Little E<lt>stevan@iinteractive.comE<gt>
=head1 COPYRIGHT AND LICENSE
projects / gitmo/Class-MOP.git / blobdiff