X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FClass%2FMOP%2FClass.pm;h=aca8a507231afbbf46f4a4b33e402055e3e2d28d;hb=b9d9fc0b01c940ad89c092eaf01e67c23b6036d5;hp=a2bc46df7db90b2d420fdbfd19ede042651123dd;hpb=552e3d24bc4b3f3f524be6f4bed4720485eb6cf2;p=gitmo%2FClass-MOP.git
diff --git a/lib/Class/MOP/Class.pm b/lib/Class/MOP/Class.pm
index a2bc46d..aca8a50 100644
--- a/lib/Class/MOP/Class.pm
+++ b/lib/Class/MOP/Class.pm
@@ -5,28 +5,193 @@ use strict;
use warnings;
use Carp 'confess';
-use Scalar::Util 'blessed', 'reftype';
+use Scalar::Util 'blessed', 'reftype', 'weaken';
use Sub::Name 'subname';
use B 'svref_2object';
-our $VERSION = '0.01';
+our $VERSION = '0.18';
+our $AUTHORITY = 'cpan:STEVAN';
+
+use base 'Class::MOP::Module';
+
+use Class::MOP::Instance;
+
+# Self-introspection
+
+sub meta { Class::MOP::Class->initialize(blessed($_[0]) || $_[0]) }
# Creation
+
+sub initialize {
+ my $class = shift;
+ my $package_name = shift;
+ (defined $package_name && $package_name && !blessed($package_name))
+ || confess "You must pass a package name and it cannot be blessed";
+ $class->construct_class_instance(':package' => $package_name, @_);
+}
+
+sub reinitialize {
+ my $class = shift;
+ my $package_name = shift;
+ (defined $package_name && $package_name && !blessed($package_name))
+ || confess "You must pass a package name and it cannot be blessed";
+ Class::MOP::remove_metaclass_by_name($package_name);
+ $class->construct_class_instance(':package' => $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 %options = @_;
+ my $package_name = $options{':package'};
+ (defined $package_name && $package_name)
+ || confess "You must pass a package name";
+ # NOTE:
+ # return the metaclass if we have it cached,
+ # and it is still defined (it has not been
+ # reaped by DESTROY yet, which can happen
+ # annoyingly enough during global destruction)
+ return Class::MOP::get_metaclass_by_name($package_name)
+ if Class::MOP::does_metaclass_exist($package_name);
+
+ # NOTE:
+ # we need to deal with the possibility
+ # of class immutability here, and then
+ # get the name of the class appropriately
+ $class = (blessed($class)
+ ? ($class->is_immutable
+ ? $class->get_mutable_metaclass_name()
+ : blessed($class))
+ : $class);
+
+ $class = blessed($class) || $class;
+ # now create the metaclass
+ my $meta;
+ if ($class =~ /^Class::MOP::Class$/) {
+ no strict 'refs';
+ $meta = bless {
+ # inherited from Class::MOP::Package
+ '$:package' => $package_name,
+ '%:namespace' => \%{$package_name . '::'},
+ # inherited from Class::MOP::Module
+ '$:version' => (exists ${$package_name . '::'}{'VERSION'} ? ${$package_name . '::VERSION'} : undef),
+ '$:authority' => (exists ${$package_name . '::'}{'AUTHORITY'} ? ${$package_name . '::AUTHORITY'} : undef),
+ # defined here ...
+ '%:attributes' => {},
+ '$:attribute_metaclass' => $options{':attribute_metaclass'} || 'Class::MOP::Attribute',
+ '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method',
+ '$:instance_metaclass' => $options{':instance_metaclass'} || 'Class::MOP::Instance',
+ } => $class;
+ }
+ else {
+ # NOTE:
+ # it is safe to use meta here because
+ # class will always be a subclass of
+ # Class::MOP::Class, which defines meta
+ $meta = $class->meta->construct_instance(%options)
+ }
+
+ # and check the metaclass compatibility
+ $meta->check_metaclass_compatability();
+
+ Class::MOP::store_metaclass_by_name($package_name, $meta);
+
+ # NOTE:
+ # we need to weaken any anon classes
+ # so that they can call DESTROY properly
+ Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
+
+ $meta;
+}
+
+sub check_metaclass_compatability {
+ my $self = shift;
+
+ # this is always okay ...
+ return if blessed($self) eq 'Class::MOP::Class' &&
+ $self->instance_metaclass eq 'Class::MOP::Instance';
+
+ my @class_list = $self->class_precedence_list;
+ shift @class_list; # shift off $self->name
+
+ foreach my $class_name (@class_list) {
+ my $meta = Class::MOP::get_metaclass_by_name($class_name) || next;
+
+ # NOTE:
+ # we need to deal with the possibility
+ # of class immutability here, and then
+ # get the name of the class appropriately
+ my $meta_type = ($meta->is_immutable
+ ? $meta->get_mutable_metaclass_name()
+ : blessed($meta));
+
+ ($self->isa($meta_type))
+ || confess $self->name . "->meta => (" . (blessed($self)) . ")" .
+ " is not compatible with the " .
+ $class_name . "->meta => (" . ($meta_type) . ")";
+ # NOTE:
+ # we also need to check that instance metaclasses
+ # are compatabile in the same the class.
+ ($self->instance_metaclass->isa($meta->instance_metaclass))
+ || confess $self->name . "->meta => (" . ($self->instance_metaclass) . ")" .
+ " is not compatible with the " .
+ $class_name . "->meta => (" . ($meta->instance_metaclass) . ")";
+ }
+}
+
+## ANON classes
{
- # Metaclasses are singletons, so we cache them here.
- # 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;
- 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;
+ # NOTE:
+ # this should be sufficient, if you have a
+ # use case where it is not, write a test and
+ # I will change it.
+ my $ANON_CLASS_SERIAL = 0;
+
+ # NOTE:
+ # we need a sufficiently annoying prefix
+ # this should suffice for now, this is
+ # used in a couple of places below, so
+ # need to put it up here for now.
+ my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
+
+ sub is_anon_class {
+ my $self = shift;
+ $self->name =~ /^$ANON_CLASS_PREFIX/ ? 1 : 0;
+ }
+
+ sub create_anon_class {
+ my ($class, %options) = @_;
+ my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
+ return $class->create($package_name, '0.00', %options);
+ }
+
+ # NOTE:
+ # this will only get called for
+ # anon-classes, all other calls
+ # are assumed to occur during
+ # global destruction and so don't
+ # really need to be handled explicitly
+ sub DESTROY {
+ my $self = shift;
+ return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
+ my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
+ no strict 'refs';
+ foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
+ delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
+ }
+ delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
}
+
}
+# creating classes with MOP ...
+
sub create {
my ($class, $package_name, $package_version, %options) = @_;
(defined $package_name && $package_name)
@@ -37,36 +202,116 @@ sub create {
eval $code;
confess "creation of $package_name failed : $@" if $@;
my $meta = $class->initialize($package_name);
+
+ $meta->add_method('meta' => sub {
+ $class->initialize(blessed($_[0]) || $_[0]);
+ });
+
$meta->superclasses(@{$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;
}
-# Informational
+## Attribute readers
-sub name { ${$_[0]} }
+# NOTE:
+# all these attribute readers will be bootstrapped
+# away in the Class::MOP bootstrap section
-sub version {
- my $self = shift;
- no strict 'refs';
- ${$self->name . '::VERSION'};
+sub get_attribute_map { $_[0]->{'%:attributes'} }
+sub attribute_metaclass { $_[0]->{'$:attribute_metaclass'} }
+sub method_metaclass { $_[0]->{'$:method_metaclass'} }
+sub instance_metaclass { $_[0]->{'$:instance_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');
+ return $class->construct_instance(@_);
+}
+
+sub construct_instance {
+ my ($class, %params) = @_;
+ my $meta_instance = $class->get_meta_instance();
+ my $instance = $meta_instance->create_instance();
+ foreach my $attr ($class->compute_all_applicable_attributes()) {
+ $attr->initialize_instance_slot($meta_instance, $instance, \%params);
+ }
+ return $instance;
+}
+
+sub get_meta_instance {
+ my $class = shift;
+ return $class->instance_metaclass->new(
+ $class,
+ $class->compute_all_applicable_attributes()
+ );
+}
+
+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');
+ $class->clone_instance($instance, @_);
+}
+
+sub clone_instance {
+ my ($class, $instance, %params) = @_;
+ (blessed($instance))
+ || confess "You can only clone instances, \$self is not a blessed instance";
+ my $meta_instance = $class->get_meta_instance();
+ my $clone = $meta_instance->clone_instance($instance);
+ foreach my $key (keys %params) {
+ next unless $meta_instance->is_valid_slot($key);
+ $meta_instance->set_slot_value($clone, $key, $params{$key});
+ }
+ return $clone;
}
# Inheritance
sub superclasses {
my $self = shift;
- no strict 'refs';
if (@_) {
my @supers = @_;
- @{$self->name . '::ISA'} = @supers;
+ @{$self->get_package_symbol('@ISA')} = @supers;
+ # NOTE:
+ # we need to check the metaclass
+ # compatability here so that we can
+ # be sure that the superclass is
+ # not potentially creating an issues
+ # we don't know about
+ $self->check_metaclass_compatability();
}
- @{$self->name . '::ISA'};
+ @{$self->get_package_symbol('@ISA')};
}
sub class_precedence_list {
@@ -76,8 +321,8 @@ sub class_precedence_list {
# This will do nothing if all is well, and blow
# up otherwise. Yes, it's an ugly hack, better
# suggestions are welcome.
- { $self->name->isa('This is a test for circular inheritance') }
- # ... and no back to our regularly scheduled program
+ { ($self->name || return)->isa('This is a test for circular inheritance') }
+ # ... and now back to our regularly scheduled program
(
$self->name,
map {
@@ -93,35 +338,116 @@ sub add_method {
(defined $method_name && $method_name)
|| confess "You must define a method name";
# use reftype here to allow for blessed subs ...
- (reftype($method) && reftype($method) eq 'CODE')
+ ('CODE' eq (reftype($method) || ''))
|| confess "Your code block must be a CODE reference";
my $full_method_name = ($self->name . '::' . $method_name);
-
- no strict 'refs';
- no warnings 'redefine';
- *{$full_method_name} = subname $full_method_name => $method;
+
+ # FIXME:
+ # dont bless subs, its bad mkay
+ $method = $self->method_metaclass->wrap($method) unless blessed($method);
+
+ $self->add_package_symbol("&${method_name}" => subname $full_method_name => $method);
}
{
-
- ## 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 } };
-
- sub has_method {
+ my $fetch_and_prepare_method = sub {
my ($self, $method_name) = @_;
+ # fetch it locally
+ my $method = $self->get_method($method_name);
+ # if we dont have local ...
+ unless ($method) {
+ # try to find the next method
+ $method = $self->find_next_method_by_name($method_name);
+ # die if it does not exist
+ (defined $method)
+ || confess "The method '$method_name' is not found in the inherience hierarchy for this class";
+ # and now make sure to wrap it
+ # even if it is already wrapped
+ # because we need a new sub ref
+ $method = Class::MOP::Method::Wrapped->wrap($method);
+ }
+ else {
+ # now make sure we wrap it properly
+ $method = Class::MOP::Method::Wrapped->wrap($method)
+ unless $method->isa('Class::MOP::Method::Wrapped');
+ }
+ $self->add_method($method_name => $method);
+ return $method;
+ };
+
+ sub add_before_method_modifier {
+ my ($self, $method_name, $method_modifier) = @_;
+ (defined $method_name && $method_name)
+ || confess "You must pass in a method name";
+ my $method = $fetch_and_prepare_method->($self, $method_name);
+ $method->add_before_modifier(subname ':before' => $method_modifier);
+ }
+
+ sub add_after_method_modifier {
+ my ($self, $method_name, $method_modifier) = @_;
(defined $method_name && $method_name)
- || confess "You must define a method name";
+ || confess "You must pass in a method name";
+ my $method = $fetch_and_prepare_method->($self, $method_name);
+ $method->add_after_modifier(subname ':after' => $method_modifier);
+ }
- my $sub_name = ($self->name . '::' . $method_name);
+ sub add_around_method_modifier {
+ my ($self, $method_name, $method_modifier) = @_;
+ (defined $method_name && $method_name)
+ || confess "You must pass in a method name";
+ my $method = $fetch_and_prepare_method->($self, $method_name);
+ $method->add_around_modifier(subname ':around' => $method_modifier);
+ }
+
+ # NOTE:
+ # the methods above used to be named like this:
+ # ${pkg}::${method}:(before|after|around)
+ # but this proved problematic when using one modifier
+ # to wrap multiple methods (something which is likely
+ # to happen pretty regularly IMO). So instead of naming
+ # it like this, I have chosen to just name them purely
+ # with their modifier names, like so:
+ # :(before|after|around)
+ # The fact is that in a stack trace, it will be fairly
+ # evident from the context what method they are attached
+ # to, and so don't need the fully qualified name.
+}
+
+sub alias_method {
+ my ($self, $method_name, $method) = @_;
+ (defined $method_name && $method_name)
+ || confess "You must define a method name";
+ # use reftype here to allow for blessed subs ...
+ ('CODE' eq (reftype($method) || ''))
+ || confess "Your code block must be a CODE reference";
+
+ # FIXME:
+ # dont bless subs, its bad mkay
+ $method = $self->method_metaclass->wrap($method) unless blessed($method);
- no strict 'refs';
- return 0 if !defined(&{$sub_name});
- return 0 if $_find_subroutine_package_name->(\&{$sub_name}) ne $self->name &&
- $_find_subroutine_name->(\&{$sub_name}) ne '__ANON__';
- return 1;
- }
+ $self->add_package_symbol("&${method_name}" => $method);
+}
+sub find_method_by_name {
+ my ($self, $method_name) = @_;
+ return $self->name->can($method_name);
+}
+
+sub has_method {
+ my ($self, $method_name) = @_;
+ (defined $method_name && $method_name)
+ || confess "You must define a method name";
+
+ return 0 if !$self->has_package_symbol("&${method_name}");
+ my $method = $self->get_package_symbol("&${method_name}");
+ return 0 if (svref_2object($method)->GV->STASH->NAME || '') ne $self->name &&
+ (svref_2object($method)->GV->NAME || '') ne '__ANON__';
+
+ # FIXME:
+ # dont bless subs, its bad mkay
+ $self->method_metaclass->wrap($method) unless blessed($method);
+
+ return 1;
}
sub get_method {
@@ -129,10 +455,9 @@ sub get_method {
(defined $method_name && $method_name)
|| confess "You must define a method name";
- no strict 'refs';
- return \&{$self->name . '::' . $method_name}
- if $self->has_method($method_name);
- return; # <- make sure to return undef
+ return unless $self->has_method($method_name);
+
+ return $self->get_package_symbol("&${method_name}");
}
sub remove_method {
@@ -142,8 +467,7 @@ sub remove_method {
my $removed_method = $self->get_method($method_name);
- no strict 'refs';
- delete ${$self->name . '::'}{$method_name}
+ $self->remove_package_symbol("&${method_name}")
if defined $removed_method;
return $removed_method;
@@ -151,8 +475,7 @@ sub remove_method {
sub get_method_list {
my $self = shift;
- no strict 'refs';
- grep { $self->has_method($_) } %{$self->name . '::'};
+ grep { $self->has_method($_) } $self->list_all_package_symbols;
}
sub compute_all_applicable_methods {
@@ -181,30 +504,6 @@ sub compute_all_applicable_methods {
return @methods;
}
-## Recursive Version of compute_all_applicable_methods
-# sub compute_all_applicable_methods {
-# my ($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)
@@ -227,18 +526,126 @@ sub find_all_methods_by_name {
} if $meta->has_method($method_name);
}
return @methods;
+}
+sub find_next_method_by_name {
+ my ($self, $method_name) = @_;
+ (defined $method_name && $method_name)
+ || confess "You must define a method name to find";
+ # 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;
+ my @cpl = $self->class_precedence_list();
+ shift @cpl; # discard ourselves
+ foreach my $class (@cpl) {
+ next if $seen_class{$class};
+ $seen_class{$class}++;
+ # fetch the meta-class ...
+ my $meta = $self->initialize($class);
+ return $meta->get_method($method_name)
+ if $meta->has_method($method_name);
+ }
+ return;
}
## 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 = 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 $self->get_attribute_map->{$attribute_name} ? 1 : 0;
+}
+
+sub get_attribute {
+ my ($self, $attribute_name) = @_;
+ (defined $attribute_name && $attribute_name)
+ || confess "You must define an attribute name";
+ return $self->get_attribute_map->{$attribute_name}
+ if $self->has_attribute($attribute_name);
+ return;
+}
+
+sub remove_attribute {
+ my ($self, $attribute_name) = @_;
+ (defined $attribute_name && $attribute_name)
+ || confess "You must define an attribute name";
+ my $removed_attribute = $self->get_attribute_map->{$attribute_name};
+ return unless defined $removed_attribute;
+ delete $self->get_attribute_map->{$attribute_name};
+ $removed_attribute->remove_accessors();
+ $removed_attribute->detach_from_class();
+ return $removed_attribute;
+}
+
+sub get_attribute_list {
+ my $self = shift;
+ keys %{$self->get_attribute_map};
+}
+
+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;
+}
+
+sub find_attribute_by_name {
+ my ($self, $attr_name) = @_;
+ # 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;
+ foreach my $class ($self->class_precedence_list()) {
+ next if $seen_class{$class};
+ $seen_class{$class}++;
+ # fetch the meta-class ...
+ my $meta = $self->initialize($class);
+ return $meta->get_attribute($attr_name)
+ if $meta->has_attribute($attr_name);
+ }
+ return;
+}
+
+## Class closing
+
+sub is_mutable { 1 }
+sub is_immutable { 0 }
+
+sub make_immutable {
+ return Class::MOP::Class::Immutable->make_metaclass_immutable(@_);
+}
1;
@@ -252,14 +659,67 @@ Class::MOP::Class - Class Meta Object
=head1 SYNOPSIS
+ # assuming that class Foo
+ # has been defined, you can
+
+ # use this for introspection ...
+
+ # 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
+
+This will return a B instance which is related
+to this class. Thereby allowing B to actually
+introspect itself.
+
+As with B, B 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 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
@@ -268,49 +728,137 @@ created any more than nessecary. Basically, they are singletons.
=over 4
=item B ?@superclasses,
- methods => ?%methods,
- attributes => ?%attributes)>
+ superclasses =E ?@superclasses,
+ methods =E ?%methods,
+ attributes =E ?%attributes)>
-This returns the basic Class object, bringing the specified
+This returns a B 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
+=item B ?@superclasses,
+ methods =E ?%methods,
+ attributes =E ?%attributes)>
+
+This will create an anonymous class, it works much like C but
+it does not need a C<$package_name>. Instead it will create a suitably
+unique package name for you to stash things into.
+
+=item B
+
+This initializes and returns returns a B object
+for a given a C<$package_name>.
+
+=item B
-This initializes a Class object for a given a C<$package_name>.
+This removes the old metaclass, and creates a new one in it's place.
+Do B use this unless you really know what you are doing, it could
+very easily make a very large mess of your program.
+
+=item B
+
+This will construct an instance of B, it is
+here so that we can actually "tie the knot" for B
+to use C once all the bootstrapping is done. This
+method is used internally by C and should never be called
+from outside of that method really.
+
+=item B
+
+This method is called as the very last thing in the
+C method. This will check that the
+metaclass you are creating is compatible with the metaclasses of all
+your ancestors. For more inforamtion about metaclass compatibility
+see the C section in L.
=back
-=head2 Instance construction
+=head2 Object instance construction and cloning
+
+These methods are B, it is up to you whether you want
+to use them or not.
=over 4
-=item B
+=item B
+
+=item B
-This will construct and instance using the C<$canidate> as storage
+=item B
+
+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 this method like so:
+
+ sub MyClass::new {
+ my ($class, %param) = @_;
+ $class->meta->new_object(%params);
+ }
+
+Of course the ideal place for this would actually be in C
+but that is considered bad style, so we do not do that.
+
+=item B
+
+This method is used to construct an instace structure suitable for
+C-ing into your package of choice. It works in conjunction
+with the Attribute protocol to collect all applicable attributes.
+
+This will construct and instance using a HASH ref as storage
(currently only HASH references are supported). This will collect all
-the applicable attribute meta-objects and layout out the fields in the
-C<$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
+
+This is a convience method for cloning an object instance, then
+blessing it into the appropriate package. This method will call
+C, which performs a shallow copy of the object,
+see that methods documentation for more details. Ideally your
+class would call a C 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
+but that is considered bad style, so we do not do that.
+
+=item B
+
+This method is a compliment of C (which means if
+you override C, you need to override this one too),
+and clones the instance shallowly.
+
+The cloned structure returned is (like with C) an
+unCed HASH reference, it is your responsibility to then bless
+this cloned structure into the right class (which C will
+do for you).
+
+As of 0.11, this method will clone the C<$instance> structure shallowly,
+as opposed to the deep cloning implemented in prior versions. After much
+thought, research and discussion, I have decided that anything but basic
+shallow cloning is outside the scope of the meta-object protocol. I
+think Yuval "nothingmuch" Kogman put it best when he said that cloning
+is too I to be part of the MOP.
=back
=head2 Informational
-=over 4
+These are a few predicate methods for asking information about the class.
-=item B
+=over 4
-This is a read-only attribute which returns the package name that
-the Class is stored in.
+=item B
-=item B
+=item B
-This is a read-only attribute which returns the C<$VERSION> of the
-package the Class is stored in.
+=item B
=back
@@ -321,13 +869,21 @@ package the Class is stored in.
=item B
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 instance is
+associated with. Basically, it can get and set the C<@ISA> for you.
+
+B
+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
-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 does, but we don't remove duplicate names.
=back
@@ -335,21 +891,34 @@ in which method dispatch will be done.
=over 4
+=item B
+
=item B
This will take a C<$method_name> and CODE reference to that
-C<$method> and install it into the Class.
+C<$method> and install it into the class's package.
-B : This does absolutely nothing special to C<$method>
+B:
+This does absolutely nothing special to C<$method>
other than use B to make sure it is tagged with the
correct name, and therefore show up correctly in stack traces and
such.
+=item B
+
+This will take a C<$method_name> and CODE reference to that
+C<$method> and alias the method into the class's package.
+
+B:
+Unlike C, this will B try to name the
+C<$method> using B, it only aliases the method in
+the class's package.
+
=item B
-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<$method_name>. It will I however, attempt to check
-if the class inherits the method.
+if the class inherits the method (use C for that).
This will correctly handle functions defined outside of the package
that use a fully qualified name (C).
@@ -367,16 +936,23 @@ may be a valid method being applied to the class.
In short, this method cannot always be trusted to determine if the
C<$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
This will return a CODE reference of the specified C<$method_name>,
or return undef if that method does not exist.
+=item B
+
+This will return a CODE reference of the specified C<$method_name>,
+or return undef if that method does not exist.
+
+Unlike C this will also look in the superclasses.
+
=item B
-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 to clear the methods associated name.
@@ -389,8 +965,8 @@ methods, use the C method.
=item B
-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.
@@ -409,6 +985,110 @@ duplicates in it. This is especially useful for things like object
initialization and destruction where you only want the method called
once, and in the correct order.
+=item B
+
+This will return the first method to match a given C<$method_name> in
+the superclasses, this is basically equivalent to calling
+C, but it can be dispatched at runtime.
+
+=back
+
+=head2 Method Modifiers
+
+Method modifiers are a concept borrowed from CLOS, in which a method
+can be wrapped with I, I and I method modifiers
+that will be called everytime the method is called.
+
+=head3 How method modifiers work?
+
+Method modifiers work by wrapping the original method and then replacing
+it in the classes symbol table. The wrappers will handle calling all the
+modifiers in the appropariate orders and preserving the calling context
+for the original method.
+
+Each method modifier serves a particular purpose, which may not be
+obvious to users of other method wrapping modules. To start with, the
+return values of I and I modifiers are ignored. This is
+because thier purpose is B to filter the input and output of the
+primary method (this is done with an I modifier). This may seem
+like an odd restriction to some, but doing this allows for simple code
+to be added at the begining or end of a method call without jeapordizing
+the normal functioning of the primary method or placing any extra
+responsibility on the code of the modifier. Of course if you have more
+complex needs, then use the I modifier, which uses a variation
+of continutation passing style to allow for a high degree of flexibility.
+
+Before and around modifiers are called in last-defined-first-called order,
+while after modifiers are called in first-defined-first-called order. So
+the call tree might looks something like this:
+
+ before 2
+ before 1
+ around 2
+ around 1
+ primary
+ after 1
+ after 2
+
+To see examples of using method modifiers, see the following examples
+included in the distribution; F, F,
+F and F. There is also a
+classic CLOS usage example in the test F<017_add_method_modifier.t>.
+
+=head3 What is the performance impact?
+
+Of course there is a performance cost associated with method modifiers,
+but we have made every effort to make that cost be directly proportional
+to the amount of modifier features you utilize.
+
+The wrapping method does it's best to B do as much work as it
+absolutely needs to. In order to do this we have moved some of the
+performance costs to set-up time, where they are easier to amortize.
+
+All this said, my benchmarks have indicated the following:
+
+ simple wrapper with no modifiers 100% slower
+ simple wrapper with simple before modifier 400% slower
+ simple wrapper with simple after modifier 450% slower
+ simple wrapper with simple around modifier 500-550% slower
+ simple wrapper with all 3 modifiers 1100% slower
+
+These numbers may seem daunting, but you must remember, every feature
+comes with some cost. To put things in perspective, just doing a simple
+C which does nothing but extract the name of the method called
+and return it costs about 400% over a normal method call.
+
+=over 4
+
+=item B
+
+This will wrap the method at C<$method_name> and the supplied C<$code>
+will be passed the C<@_> arguments, and called before the original
+method is called. As specified above, the return value of the I
+method modifiers is ignored, and it's ability to modify C<@_> is
+fairly limited. If you need to do either of these things, use an
+C method modifier.
+
+=item B
+
+This will wrap the method at C<$method_name> so that the original
+method will be called, it's return values stashed, and then the
+supplied C<$code> will be passed the C<@_> arguments, and called.
+As specified above, the return value of the I method
+modifiers is ignored, and it cannot modify the return values of
+the original method. If you need to do either of these things, use an
+C method modifier.
+
+=item B
+
+This will wrap the method at C<$method_name> so that C<$code>
+will be called and passed the original method as an extra argument
+at the begining of the C<@_> argument list. This is a variation of
+continuation passing style, where the function prepended to C<@_>
+can be considered a continuation. It is up to C<$code> if it calls
+the original method or not, there is no restriction on what the
+C<$code> can or cannot do.
+
=back
=head2 Attributes
@@ -416,22 +1096,32 @@ once, and in the correct order.
It should be noted that since there is no one consistent way to define
the attributes of a class in Perl 5. These methods can only work with
the information given, and can not easily discover information on
-their own.
+their own. See L for more details.
=over 4
+=item B
+
+=item B
+
=item B
-This stores a C<$attribute_meta_object> in the Class object and
-associates it with the C<$attribute_name>. Unlike methods, attributes
-within the MOP are stored as meta-information only. They will be used
-later to construct instances from (see C above).
+This stores a C<$attribute_meta_object> in the B
+instance associated with the given class, and associates it with
+the C<$attribute_name>. Unlike methods, attributes within the MOP
+are stored as meta-information only. They will be used later to
+construct instances from (see C above).
More details about the attribute meta-objects can be found in the
-L section of this document.
+L or the L
+section.
+
+It should be noted that any accessor, reader/writer or predicate
+methods which the C<$attribute_meta_object> has will be installed
+into the class at this time.
=item B
-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<$attribute_name> and returns a boolean.
=item B
@@ -444,10 +1134,18 @@ if none is found, it will return undef.
This will remove the attribute meta-object stored at
C<$attribute_name>, then return the removed attribute meta-object.
-B Removing an attribute will only affect future instances of
+B
+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<$attribute_name>
+has will be removed from the class at this time. This B make
+these attributes somewhat inaccessable in previously created
+instances. But if you are crazy enough to do this at runtime, then
+you are crazy enough to deal with something like this :).
+
=item B
This returns a list of attribute names which are defined in the local
@@ -456,23 +1154,33 @@ use the C method.
=item B
-This will traverse the inheritance heirachy and return a list of HASH
-references for all the applicable attributes for this class. The HASH
-references will contain the following information; the attribute name,
-the class which the attribute is associated with and the actual
-attribute meta-object
+This will traverse the inheritance heirachy and return a list of all
+the applicable attributes for this class. It does not construct a
+HASH reference like C because all
+that same information is discoverable through the attribute
+meta-object itself.
+
+=item B
-=item B
+This method will traverse the inheritance heirachy and find the
+first attribute whose name matches C<$attr_name>, then return it.
+It will return undef if nothing is found.
-This will communicate with all of the classes attributes to create
-and install the appropriate accessors. (see L
-below for more details).
+=back
+
+=head2 Class closing
+
+=over 4
+
+=item B
=back
-=head1 AUTHOR
+=head1 AUTHORS
+
+Stevan Little Estevan@iinteractive.comE
-Stevan Little Estevan@iinteractive.comE
+Yuval Kogman Enothingmuch@woobling.comE
=head1 COPYRIGHT AND LICENSE
@@ -483,4 +1191,4 @@ L
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
-=cut
\ No newline at end of file
+=cut