use Sub::Name 'subname';
use B 'svref_2object';
-our $VERSION = '0.01';
+our $VERSION = '0.03';
+
+# Self-introspection
+
+sub meta { Class::MOP::Class->initialize($_[0]) }
# Creation
# After all, do package definitions even get reaped?
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";
- $METAS{$package_name} ||= bless \$package_name => blessed($class) || $class;
+ || confess "You must pass a package name";
+ # make sure the package name is not blessed
+ $package_name = blessed($package_name) || $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 = shift;
+ my $package_name = shift;
+ (defined $package_name && $package_name)
+ || confess "You must pass a package name";
+ $class = blessed($class) || $class;
+ if ($class =~ /^Class::MOP::/) {
+ bless {
+ '$:package' => $package_name,
+ '%:attributes' => {},
+ '$:attribute_metaclass' => 'Class::MOP::Attribute',
+ '$:method_metaclass' => 'Class::MOP::Method',
+ } => $class;
+ }
+ else {
+ bless $class->meta->construct_instance(':package' => $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 $meta;
}
+# Instance Construction & Cloning
+
+
+sub construct_instance {
+ my ($class, %params) = @_;
+ my $instance = {};
+ foreach my $attr ($class->compute_all_applicable_attributes()) {
+ 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();
+ $instance->{$attr->name} = $val;
+ }
+ return $instance;
+}
+
+sub clone_instance {
+ my ($class, $self, %params) = @_;
+ (blessed($self))
+ || confess "You can only clone instances, \$self is not a blessed instance";
+ # NOTE:
+ # this should actually do a deep clone
+ # instead of this cheap hack. I will
+ # add that in later.
+ # (use the Class::Cloneable::Util code)
+ my $clone = { %{$self} };
+ foreach my $attr ($class->compute_all_applicable_attributes()) {
+ my $init_arg = $attr->has_init_arg() ? $attr->init_arg() : $attr->name;
+ # 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]} }
+sub name { $_[0]->{'$:package'} }
sub version {
my $self = shift;
## Methods
+# un-used right now ...
+sub method_metaclass { $_[0]->{'$:method_metaclass'} }
+
sub add_method {
my ($self, $method_name, $method) = @_;
(defined $method_name && $method_name)
{
## 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 attribute_metaclass { $_[0]->{'$:attribute_metaclass'} }
+
+sub add_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();
+ $self->{'%:attrs'}->{$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();
+ $removed_attribute->detach_from_class();
+ 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 => $meta->get_attribute($attr_name);
+ }
+ }
+ return @attrs;
+}
+
+# Class attributes
+
+sub add_package_variable {
+ my ($self, $variable, $initial_value) = @_;
+ (defined $variable && $variable =~ /^[\$\@\%]/)
+ || confess "variable name does not have a sigil";
+
+ my ($sigil, $name) = ($variable =~ /^(.)(.*)$/);
+ if (defined $initial_value) {
+ no strict 'refs';
+ *{$self->name . '::' . $name} = $initial_value;
+ }
+ else {
+ eval $sigil . $self->name . '::' . $name;
+ confess "Could not create package variable ($variable) because : $@" if $@;
+ }
+}
+
+sub has_package_variable {
+ my ($self, $variable) = @_;
+ (defined $variable && $variable =~ /^[\$\@\%]/)
+ || confess "variable name does not have a sigil";
+ my ($sigil, $name) = ($variable =~ /^(.)(.*)$/);
+ no strict 'refs';
+ defined ${$self->name . '::'}{$name} ? 1 : 0;
+}
+
+sub get_package_variable {
+ my ($self, $variable) = @_;
+ (defined $variable && $variable =~ /^[\$\@\%]/)
+ || confess "variable name does not have a sigil";
+ my ($sigil, $name) = ($variable =~ /^(.)(.*)$/);
+ no strict 'refs';
+ # try to fetch it first,.. see what happens
+ eval '\\' . $sigil . $self->name . '::' . $name;
+ confess "Could not get the package variable ($variable) because : $@" if $@;
+ # if we didn't die, then we can return it
+ # NOTE:
+ # this is not ideal, better suggestions are welcome
+ eval '\\' . $sigil . $self->name . '::' . $name;
+}
+
+sub remove_package_variable {
+ my ($self, $variable) = @_;
+ (defined $variable && $variable =~ /^[\$\@\%]/)
+ || confess "variable name does not have a sigil";
+ my ($sigil, $name) = ($variable =~ /^(.)(.*)$/);
+ no strict 'refs';
+ delete ${$self->name . '::'}{$name};
+}
1;
=head1 SYNOPSIS
+ # use this for introspection ...
+
+ package Foo;
+ sub meta { Class::MOP::Class->initialize(__PACKAGE__) }
+
+ # elsewhere in the code ...
+
+ # add a method to Foo ...
+ Foo->meta->add_method('bar' => sub { ... })
+
+ # get a list of all the classes searched
+ # the method dispatcher in the correct order
+ Foo->meta->class_precedence_list()
+
+ # remove a method from Foo
+ Foo->meta->remove_method('bar');
+
+ # or use this to actually create classes ...
+
+ Class::MOP::Class->create('Bar' => '0.01' => (
+ superclasses => [ 'Foo' ],
+ attributes => [
+ Class::MOP:::Attribute->new('$bar'),
+ Class::MOP:::Attribute->new('$baz'),
+ ],
+ methods => {
+ calculate_bar => sub { ... },
+ construct_baz => sub { ... }
+ }
+ ));
+
=head1 DESCRIPTION
+This is the largest and currently most complex part of the Perl 5
+meta-object protocol. It controls the introspection and
+manipulation of Perl 5 classes (and it can create them too). The
+best way to understand what this module can do, is to read the
+documentation for each of it's methods.
+
=head1 METHODS
+=head2 Self Introspection
+
+=over 4
+
+=item B<meta>
+
+This will return a B<Class::MOP::Class> instance which is related
+to this class. Thereby allowing B<Class::MOP::Class> to actually
+introspect itself.
+
+As with B<Class::MOP::Attribute>, B<Class::MOP> will actually
+bootstrap this module by installing a number of attribute meta-objects
+into it's metaclass. This will allow this class to reap all the benifits
+of the MOP when subclassing it.
+
+=back
+
=head2 Class construction
-These methods handle creating Class objects, which can be used to
-both create new classes, and analyze pre-existing ones.
+These methods will handle creating B<Class::MOP::Class> objects,
+which can be used to both create new classes, and analyze
+pre-existing classes.
This module will internally store references to all the instances
you create with these methods, so that they do not need to be
=over 4
=item B<create ($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 ($package_name)>
+
+This will construct an instance of B<Class::MOP::Class>, it is
+here so that we can actually "tie the knot" for B<Class::MOP::Class>
+to use C<construct_instance> once all the bootstrapping is done. This
+method is used internally by C<initialize> and should never be called
+from outside of that method really.
=back
-=head2 Instance construction
+=head2 Object instance construction and cloning
+
+These methods are B<entirely optional>, it is up to you whether you want
+to use them or not.
=over 4
-=item B<construct_instance ($canidate, %params)>
+=item B<construct_instance (%params)>
-This will construct and instance using the C<$canidate> as storage
+This method is used to construct an instace structure suitable for
+C<bless>-ing into your package of choice. It works in conjunction
+with the Attribute protocol to collect all applicable attributes.
+
+This will construct and instance using a HASH ref as storage
(currently only HASH references are supported). This will collect all
-the applicable attribute meta-objects and layout out the fields in the
-C<$canidate>, 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<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<$method_name> from the class.
It will return the CODE reference that it has removed, and will
attempt to use B<Sub::Name> to clear the methods associated name.
=item B<compute_all_applicable_methods>
-This will return a list of all the methods names this Class will
-support, taking into account inheritance. The list will be a list of
+This will return a list of all the methods names this class will
+respond to, taking into account inheritance. The list will be a list of
HASH references, each one containing the following information; method
name, the name of the class in which the method lives and a CODE
reference for the actual method.
It should be noted that since there is no one consistent way to define
the attributes of a class in Perl 5. These methods can only work with
the information given, and can not easily discover information on
-their own.
+their own. See L<Class::MOP::Attribute> for more details.
=over 4
+=item B<attribute_metaclass>
+
=item B<add_attribute ($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<$attribute_name>
+has will be removed from the class at this time. This B<will> make
+these attributes somewhat inaccessable in previously created
+instances. But if you are crazy enough to do this at runtime, then
+you are crazy enough to deal with something like this :).
+
=item B<get_attribute_list>
This returns a list of attribute names which are defined in the local
=item B<compute_all_applicable_attributes>
-This will traverse the inheritance heirachy and return a list of HASH
-references for all the applicable attributes for this class. The HASH
-references will contain the following information; the attribute name,
-the class which the attribute is associated with and the actual
-attribute meta-object
+This will traverse the inheritance heirachy and return a list of all
+the applicable attributes for this class. It does not construct a
+HASH reference like C<compute_all_applicable_methods> because all
+that same information is discoverable through the attribute
+meta-object itself.
+
+=back
+
+=head2 Package Variables
+
+Since Perl's classes are built atop the Perl package system, it is
+fairly common to use package scoped variables for things like static
+class variables. The following methods are convience methods for
+the creation and inspection of package scoped variables.
+
+=over 4
+
+=item B<add_package_variable ($variable_name, ?$initial_value)>
+
+Given a C<$variable_name>, which must contain a leading sigil, this
+method will create that variable within the package which houses the
+class. It also takes an optional C<$initial_value>, which must be a
+reference of the same type as the sigil of the C<$variable_name>
+implies.
+
+=item B<get_package_variable ($variable_name)>
+
+This will return a reference to the package variable in
+C<$variable_name>.
+
+=item B<has_package_variable ($variable_name)>
+
+Returns true (C<1>) if there is a package variable defined for
+C<$variable_name>, and false (C<0>) otherwise.
-=item B<create_all_accessors>
+=item B<remove_package_variable ($variable_name)>
-This will communicate with all of the classes attributes to create
-and install the appropriate accessors. (see L<The Attribute Protocol>
-below for more details).
+This will attempt to remove the package variable at C<$variable_name>.
=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