X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FClass%2FMOP%2FClass.pm;h=abfec6424048671cbc0a98c4833cd0dff89fb227;hb=f1dc35403251ed96f803ff9977f41a53b64eb1cd;hp=1634c8c20b7d5334f2136f5c69093f55168e050f;hpb=7b31baf476f970830c62cafa82d8f2efcd4ac1b6;p=gitmo%2FClass-MOP.git diff --git a/lib/Class/MOP/Class.pm b/lib/Class/MOP/Class.pm index 1634c8c..abfec64 100644 --- a/lib/Class/MOP/Class.pm +++ b/lib/Class/MOP/Class.pm @@ -4,80 +4,287 @@ package Class::MOP::Class; use strict; use warnings; -use Carp 'confess'; -use Scalar::Util 'blessed', 'reftype'; -use Sub::Name 'subname'; -use B 'svref_2object'; +use Class::MOP::Immutable; +use Class::MOP::Instance; +use Class::MOP::Method::Wrapped; -our $VERSION = '0.03'; +use Carp 'confess'; +use Scalar::Util 'blessed', 'weaken'; -# Self-introspection +our $VERSION = '0.78'; +$VERSION = eval $VERSION; +our $AUTHORITY = 'cpan:STEVAN'; -sub meta { Class::MOP::Class->initialize($_[0]) } +use base 'Class::MOP::Module'; # Creation +sub initialize { + my $class = shift; + + my $package_name; + + if ( @_ % 2 ) { + $package_name = shift; + } else { + my %options = @_; + $package_name = $options{package}; + } + + (defined $package_name && $package_name && !ref($package_name)) + || confess "You must pass a package name and it cannot be blessed"; + + return Class::MOP::get_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 = @_ == 1 ? $_[0] : {@_}; + 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) + + if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) { + return $meta; + } + + # NOTE: + # we need to deal with the possibility + # of class immutability here, and then + # get the name of the class appropriately + $class = (ref($class) + ? ($class->is_immutable + ? $class->get_mutable_metaclass_name() + : ref($class)) + : $class); + + # now create the metaclass + my $meta; + if ($class eq 'Class::MOP::Class') { + $meta = $class->_new($options); + } + 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 + $meta->check_metaclass_compatibility(); + + Class::MOP::store_metaclass_by_name($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 _new { + my $class = shift; + my $options = @_ == 1 ? $_[0] : {@_}; + + bless { + # inherited from Class::MOP::Package + 'package' => $options->{package}, + + # NOTE: + # since the following attributes will + # actually be loaded from the symbol + # table, and actually bypass the instance + # entirely, we can just leave these things + # listed here for reference, because they + # should not actually have a value associated + # with the slot. + 'namespace' => \undef, + + # inherited from Class::MOP::Module + 'version' => \undef, + 'authority' => \undef, + + # defined in Class::MOP::Class + 'superclasses' => \undef, + + 'methods' => {}, + 'attributes' => {}, + 'attribute_metaclass' => $options->{'attribute_metaclass'} + || 'Class::MOP::Attribute', + 'method_metaclass' => $options->{'method_metaclass'} + || 'Class::MOP::Method', + 'wrapped_method_metaclass' => $options->{'wrapped_method_metaclass'} + || 'Class::MOP::Method::Wrapped', + 'instance_metaclass' => $options->{'instance_metaclass'} + || 'Class::MOP::Instance', + }, $class; +} + +sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef } +sub update_package_cache_flag { + my $self = shift; + # NOTE: + # we can manually update the cache number + # since we are actually adding the method + # to our cache as well. This avoids us + # having to regenerate the method_map. + # - SL + $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name); +} + +sub check_metaclass_compatibility { + my $self = shift; + + # this is always okay ... + return if ref($self) eq 'Class::MOP::Class' && + $self->instance_metaclass eq 'Class::MOP::Instance'; + + my @class_list = $self->linearized_isa; + shift @class_list; # shift off $self->name + + foreach my $superclass_name (@class_list) { + my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next; + + # NOTE: + # we need to deal with the possibility + # of class immutability here, and then + # get the name of the class appropriately + my $super_meta_type + = $super_meta->is_immutable + ? $super_meta->get_mutable_metaclass_name() + : ref($super_meta); + + ($self->isa($super_meta_type)) + || confess $self->name . "->meta => (" . (ref($self)) . ")" . + " is not compatible with the " . + $superclass_name . "->meta => (" . ($super_meta_type) . ")"; + # NOTE: + # we also need to check that instance metaclasses + # are compatibile in the same the class. + ($self->instance_metaclass->isa($super_meta->instance_metaclass)) + || confess $self->name . "->meta->instance_metaclass => (" . ($self->instance_metaclass) . ")" . + " is not compatible with the " . + $superclass_name . "->meta->instance_metaclass => (" . ($super_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 = shift; - my $package_name = shift; - (defined $package_name && $package_name) - || 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: + # 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; + no warnings 'uninitialized'; + $self->name =~ /^$ANON_CLASS_PREFIX/; } - - # 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 { - # NOTE: - # it is safe to use meta here because - # class will always be a subclass of - # Class::MOP::Class, which defines meta - bless $class->meta->construct_instance(':package' => $package_name, @_) => $class + + sub create_anon_class { + my ($class, %options) = @_; + my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL; + return $class->create($package_name, %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 if Class::MOP::in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated + + no warnings 'uninitialized'; + return unless $self->name =~ /^$ANON_CLASS_PREFIX/; + # Moose does a weird thing where it replaces the metaclass for + # class when fixing metaclass incompatibility. In that case, + # we don't want to clean out the namespace now. We can detect + # that because Moose will explicitly update the singleton + # cache in Class::MOP. + my $current_meta = Class::MOP::get_metaclass_by_name($self->name); + return if $current_meta ne $self; + + my ($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) - || confess "You must pass a package name"; - my $code = "package $package_name;"; - $code .= "\$$package_name\:\:VERSION = '$package_version';" - if defined $package_version; - eval $code; - confess "creation of $package_name failed : $@" if $@; - my $meta = $class->initialize($package_name); + my ( $class, @args ) = @_; + + unshift @args, 'package' if @args % 2 == 1; + + my (%options) = @args; + my $package_name = $options{package}; + + (ref $options{superclasses} eq 'ARRAY') + || confess "You must pass an ARRAY ref of superclasses" + if exists $options{superclasses}; + + (ref $options{attributes} eq 'ARRAY') + || confess "You must pass an ARRAY ref of attributes" + if exists $options{attributes}; + + (ref $options{methods} eq 'HASH') + || confess "You must pass a HASH ref of methods" + if exists $options{methods}; + + $class->SUPER::create(%options); + + my (%initialize_options) = @args; + delete @initialize_options{qw( + package + superclasses + attributes + methods + version + authority + )}; + my $meta = $class->initialize( $package_name => %initialize_options ); + + # FIXME totally lame + $meta->add_method('meta' => sub { + $class->initialize(ref($_[0]) || $_[0]); + }); + $meta->superclasses(@{$options{superclasses}}) if exists $options{superclasses}; # NOTE: - # process attributes first, so that they can + # 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. @@ -85,150 +292,404 @@ sub create { 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; } ## Attribute readers # NOTE: -# all these attribute readers will be bootstrapped +# 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'} } +sub get_attribute_map { $_[0]->{'attributes'} } +sub attribute_metaclass { $_[0]->{'attribute_metaclass'} } +sub method_metaclass { $_[0]->{'method_metaclass'} } +sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} } +sub instance_metaclass { $_[0]->{'instance_metaclass'} } # Instance Construction & Cloning sub new_object { my $class = shift; - bless $class->construct_instance(@_) => $class->name; + + # 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 $instance = {}; + my $class = shift; + my $params = @_ == 1 ? $_[0] : {@_}; + my $meta_instance = $class->get_meta_instance(); + my $instance = $meta_instance->create_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; + $attr->initialize_instance_slot($meta_instance, $instance, $params); } + # NOTE: + # this will only work for a HASH instance type + if ($class->is_anon_class) { + (Scalar::Util::reftype($instance) eq 'HASH') + || confess "Currently only HASH based instances are supported with instance of anon-classes"; + # NOTE: + # At some point we should make this official + # as a reserved slot name, but right now I am + # going to keep it here. + # my $RESERVED_MOP_SLOT = '__MOP__'; + $instance->{'__MOP__'} = $class; + } + return $instance; +} + + +sub get_meta_instance { + my $self = shift; + $self->{'_meta_instance'} ||= $self->create_meta_instance(); +} + +sub create_meta_instance { + my $self = shift; + + my $instance = $self->instance_metaclass->new( + associated_metaclass => $self, + attributes => [ $self->compute_all_applicable_attributes() ], + ); + + $self->add_meta_instance_dependencies() + if $instance->is_dependent_on_superclasses(); + return $instance; } sub clone_object { my $class = shift; - my $instance = shift; - bless $class->clone_instance($instance, @_) => $class->name; + my $instance = shift; + (blessed($instance) && $instance->isa($class->name)) + || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)"; + + # 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, $self, %params) = @_; - (blessed($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} }; + my ($class, $instance, %params) = @_; + (blessed($instance)) + || confess "You can only clone instances, ($instance) is not a blessed instance"; + my $meta_instance = $class->get_meta_instance(); + my $clone = $meta_instance->clone_instance($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 ... - $clone->{$attr->name} = $params{$init_arg} - if exists $params{$init_arg}; + if ( defined( my $init_arg = $attr->init_arg ) ) { + if (exists $params{$init_arg}) { + $attr->set_value($clone, $params{$init_arg}); + } + } } - return $clone; + return $clone; } -# Informational +sub rebless_instance { + my ($self, $instance, %params) = @_; + + my $old_metaclass; + if ($instance->can('meta')) { + ($instance->meta->isa('Class::MOP::Class')) + || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class'; + $old_metaclass = $instance->meta; + } + else { + $old_metaclass = $self->initialize(ref($instance)); + } -# &name should be here too, but it is above -# because it gets bootstrapped away + my $meta_instance = $self->get_meta_instance(); -sub version { - my $self = shift; - no strict 'refs'; - ${$self->name . '::VERSION'}; + $self->name->isa($old_metaclass->name) + || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't."; + + # rebless! + # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8 + $meta_instance->rebless_instance_structure($_[1], $self); + + foreach my $attr ( $self->compute_all_applicable_attributes ) { + if ( $attr->has_value($instance) ) { + if ( defined( my $init_arg = $attr->init_arg ) ) { + $params{$init_arg} = $attr->get_value($instance) + unless exists $params{$init_arg}; + } + else { + $attr->set_value($instance, $attr->get_value($instance)); + } + } + } + + foreach my $attr ($self->compute_all_applicable_attributes) { + $attr->initialize_instance_slot($meta_instance, $instance, \%params); + } + + $instance; } # Inheritance sub superclasses { - my $self = shift; - no strict 'refs'; + my $self = shift; + my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' }; if (@_) { my @supers = @_; - @{$self->name . '::ISA'} = @supers; + @{$self->get_package_symbol($var_spec)} = @supers; + + # NOTE: + # on 5.8 and below, we need to call + # a method to get Perl to detect + # a cycle in the class hierarchy + my $class = $self->name; + $class->isa($class); + + # NOTE: + # we need to check the metaclass + # compatibility here so that we can + # be sure that the superclass is + # not potentially creating an issues + # we don't know about + + $self->check_metaclass_compatibility(); + $self->update_meta_instance_dependencies(); + } + @{$self->get_package_symbol($var_spec)}; +} + +sub subclasses { + my $self = shift; + + my $super_class = $self->name; + + if ( Class::MOP::HAVE_ISAREV() ) { + return @{ $super_class->mro::get_isarev() }; + } else { + my @derived_classes; + + my $find_derived_classes; + $find_derived_classes = sub { + my ($outer_class) = @_; + + my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} }; + + SYMBOL: + for my $symbol ( keys %$symbol_table_hashref ) { + next SYMBOL if $symbol !~ /\A (\w+):: \z/x; + my $inner_class = $1; + + next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER' + + my $class = + $outer_class + ? "${outer_class}::$inner_class" + : $inner_class; + + if ( $class->isa($super_class) and $class ne $super_class ) { + push @derived_classes, $class; + } + + next SYMBOL if $class eq 'main'; # skip 'main::*' + + $find_derived_classes->($class); + } + }; + + my $root_class = q{}; + $find_derived_classes->($root_class); + + undef $find_derived_classes; + + @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes; + + return @derived_classes; } - @{$self->name . '::ISA'}; +} + + +sub linearized_isa { + return @{ mro::get_linear_isa( (shift)->name ) }; } sub class_precedence_list { my $self = shift; - # NOTE: - # We need to check for ciruclar inheirtance here. - # 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, - map { - $self->initialize($_)->class_precedence_list() - } $self->superclasses() - ); + my $name = $self->name; + + unless (Class::MOP::IS_RUNNING_ON_5_10()) { + # NOTE: + # We need to check for circular inheritance here + # if we are are not on 5.10, cause 5.8 detects it + # late. This will do nothing if all is well, and + # blow up otherwise. Yes, it's an ugly hack, better + # suggestions are welcome. + # - SL + ($name || return)->isa('This is a test for circular inheritance') + } + + # if our mro is c3, we can + # just grab the linear_isa + if (mro::get_mro($name) eq 'c3') { + return @{ mro::get_linear_isa($name) } + } + else { + # NOTE: + # we can't grab the linear_isa for dfs + # since it has all the duplicates + # already removed. + return ( + $name, + map { + $self->initialize($_)->class_precedence_list() + } $self->superclasses() + ); + } } ## Methods +sub wrap_method_body { + my ( $self, %args ) = @_; + + ('CODE' eq ref $args{body}) + || confess "Your code block must be a CODE reference"; + + $self->method_metaclass->wrap( + package_name => $self->name, + %args, + ); +} + sub add_method { my ($self, $method_name, $method) = @_; (defined $method_name && $method_name) || confess "You must define a method name"; - # use reftype here to allow for blessed subs ... - (reftype($method) && reftype($method) eq 'CODE') - || confess "Your code block must be a CODE reference"; + + my $body; + if (blessed($method)) { + $body = $method->body; + if ($method->package_name ne $self->name) { + $method = $method->clone( + package_name => $self->name, + name => $method_name + ) if $method->can('clone'); + } + } + else { + $body = $method; + $method = $self->wrap_method_body( body => $body, name => $method_name ); + } + + $method->attach_to_class($self); + + # This used to call get_method_map, which meant we would build all + # the method objects for the class just because we added one + # method. This is hackier, but quicker too. + $self->{methods}{$method_name} = $method; + my $full_method_name = ($self->name . '::' . $method_name); - - no strict 'refs'; - no warnings 'redefine'; - *{$full_method_name} = subname $full_method_name => $method; + $self->add_package_symbol( + { sigil => '&', type => 'CODE', name => $method_name }, + Class::MOP::subname($full_method_name => $body) + ); } { + my $fetch_and_prepare_method = sub { + my ($self, $method_name) = @_; + my $wrapped_metaclass = $self->wrapped_method_metaclass; + # 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' was not found in the inheritance hierarchy for " . $self->name; + # and now make sure to wrap it + # even if it is already wrapped + # because we need a new sub ref + $method = $wrapped_metaclass->wrap($method); + } + else { + # now make sure we wrap it properly + $method = $wrapped_metaclass->wrap($method) + unless $method->isa($wrapped_metaclass); + } + $self->add_method($method_name => $method); + return $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 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( + Class::MOP::subname(':before' => $method_modifier) + ); + } - sub has_method { - my ($self, $method_name) = @_; + sub add_after_method_modifier { + my ($self, $method_name, $method_modifier) = @_; (defined $method_name && $method_name) - || confess "You must define a method name"; - - my $sub_name = ($self->name . '::' . $method_name); - - no strict 'refs'; - return 0 if !defined(&{$sub_name}); - return 0 if $_find_subroutine_package_name->(\&{$sub_name}) ne $self->name && - $_find_subroutine_name->(\&{$sub_name}) ne '__ANON__'; - return 1; + || confess "You must pass in a method name"; + my $method = $fetch_and_prepare_method->($self, $method_name); + $method->add_after_modifier( + Class::MOP::subname(':after' => $method_modifier) + ); + } + + sub add_around_method_modifier { + my ($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( + Class::MOP::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 = shift; + + $self->add_method(@_); +} + +sub has_method { + my ($self, $method_name) = @_; + (defined $method_name && $method_name) + || confess "You must define a method name"; + + exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name}; } sub get_method { @@ -236,81 +697,98 @@ 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 $self->{methods}{$method_name} || $self->get_method_map->{$method_name}; } sub remove_method { my ($self, $method_name) = @_; (defined $method_name && $method_name) || confess "You must define a method name"; + + my $removed_method = delete $self->get_method_map->{$method_name}; - my $removed_method = $self->get_method($method_name); - - no strict 'refs'; - delete ${$self->name . '::'}{$method_name} - if defined $removed_method; - + $self->remove_package_symbol( + { sigil => '&', type => 'CODE', name => $method_name } + ); + + $removed_method->detach_from_class if $removed_method; + + $self->update_package_cache_flag; # still valid, since we just removed the method from the map + return $removed_method; } sub get_method_list { my $self = shift; - no strict 'refs'; - grep { $self->has_method($_) } %{$self->name . '::'}; + keys %{$self->get_method_map}; } -sub compute_all_applicable_methods { - my $self = shift; - my @methods; - # 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_method); - foreach my $class ($self->class_precedence_list()) { - next if $seen_class{$class}; - $seen_class{$class}++; +sub find_method_by_name { + my ($self, $method_name) = @_; + (defined $method_name && $method_name) + || confess "You must define a method name to find"; + foreach my $class ($self->linearized_isa) { # fetch the meta-class ... my $meta = $self->initialize($class); - foreach my $method_name ($meta->get_method_list()) { - next if exists $seen_method{$method_name}; - $seen_method{$method_name}++; - push @methods => { - name => $method_name, - class => $class, - code => $meta->get_method($method_name) - }; - } + return $meta->get_method($method_name) + if $meta->has_method($method_name); } - return @methods; + return; +} + +sub get_all_methods { + my $self = shift; + my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa; + return values %methods; +} + +# compatibility +sub compute_all_applicable_methods { + return map { + { + name => $_->name, + class => $_->package_name, + code => $_, # sigh, overloading + }, + } shift->get_all_methods(@_); +} + +sub get_all_method_names { + my $self = shift; + my %uniq; + grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods; } sub find_all_methods_by_name { my ($self, $method_name) = @_; (defined $method_name && $method_name) - || confess "You must define a method name to find"; + || confess "You must define a method name to find"; my @methods; - # 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}++; + foreach my $class ($self->linearized_isa) { # fetch the meta-class ... my $meta = $self->initialize($class); push @methods => { - name => $method_name, + name => $method_name, class => $class, code => $meta->get_method($method_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"; + my @cpl = $self->linearized_isa; + shift @cpl; # discard ourselves + foreach my $class (@cpl) { + # fetch the meta-class ... + my $meta = $self->initialize($class); + return $meta->get_method($method_name) + if $meta->has_method($method_name); + } + return; } ## Attributes @@ -322,115 +800,249 @@ sub add_attribute { 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)"; + || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; + + # first we attach our new attribute + # because it might need certain information + # about the class which it is attached to $attribute->attach_to_class($self); - $attribute->install_accessors(); + + # then we remove attributes of a conflicting + # name here so that we can properly detach + # the old attr object, and remove any + # accessors it would have generated + if ( $self->has_attribute($attribute->name) ) { + $self->remove_attribute($attribute->name); + } else { + $self->invalidate_meta_instances(); + } + + # then onto installing the new accessors $self->get_attribute_map->{$attribute->name} = $attribute; + + # invalidate package flag here + my $e = do { local $@; eval { $attribute->install_accessors() }; $@ }; + if ( $e ) { + $self->remove_attribute($attribute->name); + die $e; + } + + return $attribute; +} + +sub update_meta_instance_dependencies { + my $self = shift; + + if ( $self->{meta_instance_dependencies} ) { + return $self->add_meta_instance_dependencies; + } +} + +sub add_meta_instance_dependencies { + my $self = shift; + + $self->remove_meta_instance_dependencies; + + my @attrs = $self->compute_all_applicable_attributes(); + + my %seen; + my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs; + + foreach my $class ( @classes ) { + $class->add_dependent_meta_instance($self); + } + + $self->{meta_instance_dependencies} = \@classes; +} + +sub remove_meta_instance_dependencies { + my $self = shift; + + if ( my $classes = delete $self->{meta_instance_dependencies} ) { + foreach my $class ( @$classes ) { + $class->remove_dependent_meta_instance($self); + } + + return $classes; + } + + return; + +} + +sub add_dependent_meta_instance { + my ( $self, $metaclass ) = @_; + push @{ $self->{dependent_meta_instances} }, $metaclass; +} + +sub remove_dependent_meta_instance { + my ( $self, $metaclass ) = @_; + my $name = $metaclass->name; + @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances}; +} + +sub invalidate_meta_instances { + my $self = shift; + $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} }; +} + +sub invalidate_meta_instance { + my $self = shift; + undef $self->{_meta_instance}; } sub has_attribute { my ($self, $attribute_name) = @_; (defined $attribute_name && $attribute_name) || confess "You must define an attribute name"; - exists $self->get_attribute_map->{$attribute_name} ? 1 : 0; -} + exists $self->get_attribute_map->{$attribute_name}; +} 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 $self->get_attribute_map->{$attribute_name} + # NOTE: + # this will return undef anyway, so no need ... + # 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}; - delete $self->get_attribute_map->{$attribute_name} - if defined $removed_attribute; - $removed_attribute->remove_accessors(); - $removed_attribute->detach_from_class(); + my $removed_attribute = $self->get_attribute_map->{$attribute_name}; + return unless defined $removed_attribute; + delete $self->get_attribute_map->{$attribute_name}; + $self->invalidate_meta_instances(); + $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 get_all_attributes { + shift->compute_all_applicable_attributes(@_); +} 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}++; + my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa; + return values %attrs; +} + +sub find_attribute_by_name { + my ($self, $attr_name) = @_; + foreach my $class ($self->linearized_isa) { # 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 $meta->get_attribute($attr_name) + if $meta->has_attribute($attr_name); + } + return; +} + +# check if we can reinitialize +sub is_pristine { + my $self = shift; + + # if any local attr is defined + return if $self->get_attribute_list; + + # or any non-declared methods + if ( my @methods = values %{ $self->get_method_map } ) { + my $metaclass = $self->method_metaclass; + foreach my $method ( @methods ) { + return if $method->isa("Class::MOP::Method::Generated"); + # FIXME do we need to enforce this too? return unless $method->isa($metaclass); } } - return @attrs; + + return 1; } -# Class attributes +## Class closing -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; +sub is_mutable { 1 } +sub is_immutable { 0 } + +sub immutable_transformer { $_[0]->{immutable_transformer} } +sub _set_immutable_transformer { $_[0]->{immutable_transformer} = $_[1] } + +{ + my %Default_Immutable_Options = ( + read_only => [qw/superclasses/], + cannot_call => [ + qw/ + add_method + alias_method + remove_method + add_attribute + remove_attribute + remove_package_symbol + / + ], + memoize => { + class_precedence_list => 'ARRAY', + # FIXME perl 5.10 memoizes this on its own, no need? + linearized_isa => 'ARRAY', + get_all_methods => 'ARRAY', + get_all_method_names => 'ARRAY', + compute_all_applicable_attributes => 'ARRAY', + get_meta_instance => 'SCALAR', + get_method_map => 'SCALAR', + }, + + # NOTE: + # this is ugly, but so are typeglobs, + # so whattayahgonnadoboutit + # - SL + wrapped => { + add_package_symbol => sub { + my $original = shift; + confess "Cannot add package symbols to an immutable metaclass" + unless ( caller(2) )[3] eq + 'Class::MOP::Package::get_package_symbol'; + + # This is a workaround for a bug in 5.8.1 which thinks that + # goto $original->body + # is trying to go to a label + my $body = $original->body; + goto $body; + }, + }, + ); + + sub make_immutable { + my $self = shift; + + return if $self->is_immutable; + + my $transformer = $self->immutable_transformer + || Class::MOP::Immutable->new( + $self, + %Default_Immutable_Options, + @_ + ); + + $self->_set_immutable_transformer($transformer); + + $transformer->make_metaclass_immutable; } - 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}; +sub make_mutable { + my $self = shift; + + return if $self->is_mutable; + + $self->immutable_transformer->make_metaclass_mutable; } 1; @@ -439,182 +1051,221 @@ __END__ =pod -=head1 NAME +=head1 NAME Class::MOP::Class - Class Meta Object =head1 SYNOPSIS + # assuming that class Foo + # has been defined, you can + # use this for introspection ... - - package Foo; - sub meta { Class::MOP::Class->initialize(__PACKAGE__) } - - # elsewhere in the code ... - + # add a method to Foo ... - Foo->meta->add_method('bar' => sub { ... }) - - # get a list of all the classes searched - # the method dispatcher in the correct order - Foo->meta->class_precedence_list() - - # remove a method from Foo - Foo->meta->remove_method('bar'); - + Foo->meta->add_method( 'bar' => sub {...} ) + + # get a list of all the classes searched + # the method dispatcher in the correct order + Foo->meta->class_precedence_list() + + # remove a method from Foo + Foo->meta->remove_method('bar'); + # or use this to actually create classes ... - - Class::MOP::Class->create('Bar' => '0.01' => ( - superclasses => [ 'Foo' ], - attributes => [ - Class::MOP:::Attribute->new('$bar'), - Class::MOP:::Attribute->new('$baz'), - ], - methods => { - calculate_bar => sub { ... }, - construct_baz => sub { ... } - } - )); + + Class::MOP::Class->create( + 'Bar' => ( + version => '0.01', + superclasses => ['Foo'], + attributes => [ + Class::MOP:: : Attribute->new('$bar'), + Class::MOP:: : Attribute->new('$baz'), + ], + methods => { + calculate_bar => sub {...}, + construct_baz => sub {...} + } + ) + ); =head1 DESCRIPTION -This is the largest and currently most complex part of the Perl 5 -meta-object protocol. It controls the introspection and -manipulation of Perl 5 classes (and it can create them too). The -best way to understand what this module can do, is to read the -documentation for each of it's methods. +The Class Protocol is the largest and most complex part of the +Class::MOP meta-object protocol. It controls the introspection and +manipulation of Perl 5 classes, and it can create them as well. The +best way to understand what this module can do, is to read the +documentation for each of its methods. + +=head1 INHERITANCE + +C is a subclass of L. =head1 METHODS -=head2 Self Introspection +=head2 Class construction + +These methods all create new C objects. These +objects can represent existing classes, or they can be used to create +new classes from scratch. + +The metaclass object for a given class is a singleton. If you attempt +to create a metaclass for the same class twice, you will just get the +existing object. =over 4 -=item B +=item B<< Class::MOP::Class->create($package_name, %options) >> + +This method creates a new C object with the given +package name. It accepts a number of options. + +=over 8 + +=item * version + +An optional version number for the newly created package. + +=item * authority -This will return a B instance which is related -to this class. Thereby allowing B to actually -introspect itself. +An optional authority for the newly created package. -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. +=item * superclasses + +An optional array reference of superclass names. + +=item * methods + +An optional hash reference of methods for the class. The keys of the +hash reference are method names, and values are subroutine references. + +=item * attributes + +An optional array reference of attributes. + +An attribute can be passed as an existing L +object, I or as a hash reference of options which will be passed +to the attribute metaclass's constructor. =back -=head2 Class construction +=item B<< Class::MOP::Class->create_anon_class(%options) >> -These methods will handle creating B objects, -which can be used to both create new classes, and analyze -pre-existing classes. +This method works just like C<< Class::MOP::Class->create >> but it +creates an "anonymous" class. In fact, the class does have a name, but +that name is a unique name generated internally by this module. -This module will internally store references to all the instances -you create with these methods, so that they do not need to be -created any more than nessecary. Basically, they are singletons. +It accepts the same C, C, and C +parameters that C accepts. -=over 4 +Anonymous classes are destroyed once the metaclass they are attached +to goes out of scope, and will be removed from Perl's internal symbol +table. + +All instances of an anonymous class keep a special reference to the +metaclass object, which prevents the metaclass from going out of scope +while any instances exist. -=item B ?@superclasses, - methods =E ?%methods, - attributes =E ?%attributes)> +This only works if the instance if based on a hash reference, however. -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<< Class::MOP::Class->initialize($package_name, %options) >> + +This method will initialize a C object for the +named package. Unlike C, this method I create a new +class. -=item B +The purpose of this method is to retrieve a C +object for introspecting an existing class. -This initializes and returns returns a B object -for a given a C<$package_name>. +If an existing C object exists for the named +package, it will be returned, and any options provided will be +ignored! -=item B +If the object does not yet exist, it will be created. -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. +The valid options that can be passed to this method are +C, C, +C, and C. These are all +optional, and default to the appropriate class in the C +distribution. =back =head2 Object instance construction and cloning -These methods are B, it is up to you whether you want -to use them or not. +These methods are all related to creating and/or cloning object +instances. =over 4 -=item B +=item B<< $metaclass->clone_object($instance, %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 this method like so: +This method clones an existing object instance. Any parameters you +provide are will override existing attribute values in the object. - sub MyClass::new { - my ($class, %param) = @_; - $class->meta->new_object(%params); - } +This is a convenience method for cloning an object instance, then +blessing it into the appropriate package. -Of course the ideal place for this would actually be in C -but that is considered bad style, so we do not do that. +You could implement a clone method in your class, using this method: -=item B + sub clone { + my ($self, %params) = @_; + $self->meta->clone_object($self, %params); + } -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. +=item B<< $metaclass->rebless_instance($instance, %params) >> -This will construct and instance using a HASH ref as storage -(currently only HASH references are supported). This will collect all -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. +This method changes the class of C<$instance> to the metaclass's class. -=item B +You can only rebless an instance into a subclass of its current +class. If you pass any additional parameters, these will be treated +like constructor parameters and used to initialize the object's +attributes. Any existing attributes that are already set will be +overwritten. -This is a convience method for cloning an object instance, then -blessing it into the appropriate package. Ideally your class -would call a C this method like so: +=item B<< $metaclass->new_object(%params) >> - sub MyClass::clone { - my ($self, %param) = @_; - $self->meta->clone_object($self, %params); - } +This method is used to create a new object of the metaclass's +class. Any parameters you provide are used to initialize the +instance's attributes. -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<< $metaclass->instance_metaclass >> -=item B +Returns the class name of the instance metaclass, see +L for more information on the instance +metaclasses. -This method is a compliment of C (which means if -you override C, you need to override this one too). +=item B<< $metaclass->get_meta_instance >> -This method will clone the C<$instance> structure created by the -C method, and apply any C<%params> passed to it -to change the attribute values. The structure returned is (like with -C) an unCed HASH reference, it is your -responsibility to then bless this cloned structure into the right -class. +Returns an instance of the C to be used in the +construction of a new instance of the class. =back -=head2 Informational +=head2 Informational predicates + +These are a few predicate methods for asking information about the +class itself. =over 4 -=item B +=item B<< $metaclass->is_anon_class >> + +This returns true if the class was created by calling C<< +Class::MOP::Class->create_anon_class >>. + +=item B<< $metaclass->is_mutable >> + +This returns true if the class is still mutable. + +=item B<< $metaclass->is_immutable >> -This is a read-only attribute which returns the package name for the -given B instance. +This returns true if the class has been made immutable. -=item B +=item B<< $metaclass->is_pristine >> -This is a read-only attribute which returns the C<$VERSION> of the -package for the given B instance. +A class is I pristine if it has non-inherited attributes or if it +has any generated methods. =back @@ -622,225 +1273,381 @@ package for the given B instance. =over 4 -=item B +=item B<< $metaclass->superclasses(@superclasses) >> -This is a read-write attribute which represents the superclass -relationships of the class the B instance is -associated with. Basically, it can get and set the C<@ISA> for you. +This is a read-write accessor which represents the superclass +relationships of the metaclass's class. -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. +This is basically sugar around getting and setting C<@ISA>. -=item B +=item B<< $metaclass->class_precedence_list >> -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. +This returns a list of all of the class's ancestor classes. The +classes are returned in method dispatch order. + +=item B<< $metaclass->linearized_isa >> + +This returns a list based on C but with all +duplicates removed. + +=item B<< $metaclass->subclasses >> + +This returns a list of subclasses for this class. =back -=head2 Methods +=head2 Method introspection and creation + +These methods allow you to introspect a class's methods, as well as +add, remove, or change methods. + +Determining what is truly a method in a Perl 5 class requires some +heuristics (aka guessing). + +Methods defined outside the package with a fully qualified name (C) will be included. Similarly, methods named +with a fully qualified name using L are also included. + +However, we attempt to ignore imported functions. + +Ultimately, we are using heuristics to determine what truly is a +method in a class, and these heuristics may get the wrong answer in +some edge cases. However, for most "normal" cases the heuristics work +correctly. =over 4 -=item B +=item B<< $metaclass->get_method($method_name) >> + +This will return a L for the specified +C<$method_name>. If the class does not have the specified method, it +returns C + +=item B<< $metaclass->has_method($method_name) >> -=item B +Returns a boolean indicating whether or not the class defines the +named method. It does not include methods inherited from parent +classes. -This will take a C<$method_name> and CODE reference to that -C<$method> and install it into the class's package. +=item B<< $metaclass->get_method_map >> -B: -This does absolutely nothing special to C<$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. +Returns a hash reference representing the methods defined in this +class. The keys are method names and the values are +L objects. -=item B +=item B<< $metaclass->get_method_list >> -This just provides a simple way to check if the class implements -a specific C<$method_name>. It will I however, attempt to check -if the class inherits the method (use C for that). +This will return a list of method I for all methods defined in +this class. -This will correctly handle functions defined outside of the package -that use a fully qualified name (C). +=item B<< $metaclass->get_all_methods >> -This will correctly handle functions renamed with B and -installed using the symbol tables. However, if you are naming the -subroutine outside of the package scope, you must use the fully -qualified name, including the package name, for C to -correctly identify it. +This will traverse the inheritance hierarchy and return a list of all +the L objects for this class and its parents. -This will attempt to correctly ignore functions imported from other -packages using B. It breaks down if the function imported -is an C<__ANON__> sub (such as with C), which very well -may be a valid method being applied to the class. +=item B<< $metaclass->find_method_by_name($method_name) >> -In short, this method cannot always be trusted to determine if the -C<$method_name> is actually a method. However, it will DWIM about -90% of the time, so it's a small trade off I think. +This will return a L for the specified +C<$method_name>. If the class does not have the specified method, it +returns C -=item B +Unlike C, this method I look for the named method in +superclasses. -This will return a CODE reference of the specified C<$method_name>, -or return undef if that method does not exist. +=item B<< $metaclass->get_all_method_names >> -=item B +This will return a list of method I for all of this class's +methods, including inherited methods. -This will attempt to remove a given C<$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. +=item B<< $metaclass->find_all_methods_by_name($method_name) >> -=item B +This method looks for the named method in the class and all of its +parents. It returns every matching method it finds in the inheritance +tree, so it returns a list of methods. -This will return a list of method names for all I defined -methods. It does B provide a list of all applicable methods, -including any inherited ones. If you want a list of all applicable -methods, use the C method. +Each method is returned as a hash reference with three keys. The keys +are C, C, and C. The C key has a +L object as its value. -=item B +The list of methods is distinct. -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. +=item B<< $metaclass->find_next_method_by_name($method_name) >> -=item B +This method returns the first method in any superclass matching the +given name. It is effectively the method that C +would dispatch to. -This will traverse the inheritence hierarchy and locate all methods -with a given C<$method_name>. Similar to -C it returns a list of HASH references -with the following information; method name (which will always be the -same as C<$method_name>), the name of the class in which the method -lives and a CODE reference for the actual method. +=item B<< $metaclass->add_method($method_name, $method) >> -The list of methods produced is a distinct list, meaning there are no -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. +This method takes a method name and a subroutine reference, and adds +the method to the class. + +The subroutine reference can be a L, and you are +strongly encouraged to pass a meta method object instead of a code +reference. If you do so, that object gets stored as part of the +class's method map directly. If not, the meta information will have to +be recreated later, and may be incorrect. + +If you provide a method object, this method will clone that object if +the object's package name does not match the class name. This lets us +track the original source of any methods added from other classes +(notably Moose roles). + +=item B<< $metaclass->remove_method($method_name) >> + +Remove the named method from the class. This method returns the +L object for the method. =back -=head2 Attributes +=head2 Attribute introspection and creation -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. See L for more details. +Because Perl 5 does not have a core concept of attributes in classes, +we can only return information about attributes which have been added +via this class's methods. We cannot discover information about +attributes which are defined in terms of "regular" Perl 5 methods. =over 4 -=item B +=item B<< $metaclass->get_attribute($attribute_name) >> + +This will return a L for the specified +C<$attribute_name>. If the class does not have the specified +attribute, it returns C + +=item B<< $metaclass->has_attribute($attribute_name) >> + +Returns a boolean indicating whether or not the class defines the +named attribute. It does not include attributes inherited from parent +classes. + +=item B<< $metaclass->get_attribute_map >> + +Returns a hash reference representing the attributes defined in this +class. The keys are attribute names and the values are +L objects. + +=item B<< $metaclass->get_attribute_list >> + +This will return a list of attributes I for all attributes +defined in this class. -=item B +=item B<< $metaclass->get_all_attributes >> -=item B +This will traverse the inheritance hierarchy and return a list of all +the L objects for this class and its parents. -This stores a C<$attribute_meta_object> in the B -instance associated with the given class, and associates it with -the C<$attribute_name>. Unlike methods, attributes within the MOP -are stored as meta-information only. They will be used later to -construct instances from (see C above). -More details about the attribute meta-objects can be found in the -L or the L -section. +This method can also be called as C. -It should be noted that any accessor, reader/writer or predicate -methods which the C<$attribute_meta_object> has will be installed -into the class at this time. +=item B<< $metaclass->find_attribute_by_name($attribute_name) >> -=item B +This will return a L for the specified +C<$attribute_name>. If the class does not have the specified +attribute, it returns C -Checks to see if this class has an attribute by the name of -C<$attribute_name> and returns a boolean. +Unlike C, this attribute I look for the named +attribute in superclasses. -=item B +=item B<< $metaclass->add_attribute(...) >> -Returns the attribute meta-object associated with C<$attribute_name>, -if none is found, it will return undef. +This method accepts either an existing L +object, or parameters suitable for passing to that class's C +method. -=item B +The attribute provided will be added to the class. -This will remove the attribute meta-object stored at -C<$attribute_name>, then return the removed attribute meta-object. +Any accessor methods defined by the attribute will be added to the +class when the attribute is added. -B -Removing an attribute will only affect future instances of -the class, it will not make any attempt to remove the attribute from -any existing instances of the class. +If an attribute of the same name already exists, the old attribute +will be removed first. -It should be noted that any accessor, reader/writer or predicate -methods which the attribute meta-object stored at C<$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<< $metaclass->remove_attribute($attribute_name) >> -=item B +This will remove the named attribute from the class, and +L object. -This returns a list of attribute names which are defined in the local -class. If you want a list of all applicable attributes for a class, -use the C method. +Removing an attribute also removes any accessor methods defined by the +attribute. -=item B +However, note that removing an attribute will only affect I +object instances created for this class, not existing instances. -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<< $metaclass->attribute_metaclass >> + +Returns the class name of the attribute metaclass for this class. By +default, this is L. for more information on + +=back + +=head2 Class Immutability + +Making a class immutable "freezes" the class definition. You can no +longer call methods which alter the class, such as adding or removing +methods or attributes. + +Making a class immutable lets us optimize the class by inlining some +methods, and also allows us to optimize some methods on the metaclass +object itself. + +The immutabilization system in L takes much greater advantage +of the inlining features than Class::MOP itself does. + +=over 4 + +=item B<< $metaclass->make_immutable(%options) >> + +This method will create an immutable transformer and uses it to make +the class and its metaclass object immutable. + +Details of how immutabilization works are in L +documentation. + +=item B<< $metaclass->make_mutable >> + +Calling this method reverse the immutabilization transformation. + +=item B<< $metaclass->immutable_transformer >> + +If the class has been made immutable previously, this returns the +L object that was created to do the +transformation. + +If the class was never made immutable, this method will die. =back -=head2 Package Variables +=head2 Method Modifiers + +Method modifiers are hooks which allow a method to be wrapped with +I, I and I method modifiers. Every time a +method is called, it's modifiers are also called. + +A class can modify its own methods, as well as methods defined in +parent classes. + +=head3 How method modifiers work? + +Method modifiers work by wrapping the original method and then +replacing it in the class's symbol table. The wrappers will handle +calling all the modifiers in the appropriate order and preserving the +calling context for the original method. + +The return values of C and C modifiers are +ignored. This is because their purpose is B to filter the input +and output of the primary method (this is done with an I +modifier). -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. +This may seem like an odd restriction to some, but doing this allows +for simple code to be added at the beginning or end of a method call +without altering the function of the wrapped method or placing any +extra responsibility on the code of the modifier. + +Of course if you have more complex needs, you can use the C +modifier which allows you to change both the parameters passed to the +wrapped method, as well as its return value. + +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 + around 1 + around 2 + after 1 + after 2 + +=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 directly +proportional to the number 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, our 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 +=item B<< $metaclass->add_before_method_modifier($method_name, $code) >> + +This wraps the specified method with the supplied subroutine +reference. The modifier will be called as a method itself, and will +receive the same arguments as are passed to the method. + +When the modifier exits, the wrapped method will be called. -Given a C<$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. +The return value of the modifier will be ignored. -=item B +=item B<< $metaclass->add_after_method_modifier($method_name, $code) >> -This will return a reference to the package variable in -C<$variable_name>. +This wraps the specified method with the supplied subroutine +reference. The modifier will be called as a method itself, and will +receive the same arguments as are passed to the method. -=item B +When the wrapped methods exits, the modifier will be called. + +The return value of the modifier will be ignored. + +=item B<< $metaclass->add_around_method_modifier($method_name, $code) >> + +This wraps the specified method with the supplied subroutine +reference. + +The first argument passed to the modifier will be a subroutine +reference to the wrapped method. The second argument is the object, +and after that come any arguments passed when the method is called. + +The around modifier can choose to call the original method, as well as +what arguments to pass if it does so. + +The return value of the modifier is what will be seen by the caller. + +=back + +=head2 Introspection + +=over 4 -Returns true (C<1>) if there is a package variable defined for -C<$variable_name>, and false (C<0>) otherwise. +=item B<< Class::MOP::Class->meta >> -=item B +This will return a L instance for this class. -This will attempt to remove the package variable at C<$variable_name>. +It should also be noted that L will actually bootstrap +this module by installing a number of attribute meta-objects into its +metaclass. =back -=head1 AUTHOR +=head1 AUTHORS Stevan Little Estevan@iinteractive.comE =head1 COPYRIGHT AND LICENSE -Copyright 2006 by Infinity Interactive, Inc. +Copyright 2006-2009 by Infinity Interactive, Inc. L This library is free software; you can redistribute it and/or modify -it under the same terms as Perl itself. +it under the same terms as Perl itself. -=cut \ No newline at end of file +=cut