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=a3ac27d3f30455a7a679d778b79849f681e4a3cb;hpb=9b522fc4b2f36a31ba00ddf00abf369c28c705c7;p=gitmo%2FClass-MOP.git diff --git a/lib/Class/MOP/Class.pm b/lib/Class/MOP/Class.pm index a3ac27d..abfec64 100644 --- a/lib/Class/MOP/Class.pm +++ b/lib/Class/MOP/Class.pm @@ -11,7 +11,8 @@ use Class::MOP::Method::Wrapped; use Carp 'confess'; use Scalar::Util 'blessed', 'weaken'; -our $VERSION = '0.33'; +our $VERSION = '0.78'; +$VERSION = eval $VERSION; our $AUTHORITY = 'cpan:STEVAN'; use base 'Class::MOP::Module'; @@ -19,21 +20,22 @@ use base 'Class::MOP::Module'; # 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"; - return Class::MOP::get_metaclass_by_name($package_name) - || $class->construct_class_instance('package' => $package_name, @_); -} + my $class = shift; -sub reinitialize { - my $class = shift; - my $package_name = shift; - (defined $package_name && $package_name && !blessed($package_name)) + 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"; - Class::MOP::remove_metaclass_by_name($package_name); - $class->construct_class_instance('package' => $package_name, @_); + + return Class::MOP::get_metaclass_by_name($package_name) + || $class->construct_class_instance(package => $package_name, @_); } # NOTE: (meta-circularity) @@ -44,8 +46,8 @@ sub reinitialize { # normal &construct_instance. sub construct_class_instance { my $class = shift; - my %options = @_; - my $package_name = $options{'package'}; + my $options = @_ == 1 ? $_[0] : {@_}; + my $package_name = $options->{package}; (defined $package_name && $package_name) || confess "You must pass a package name"; # NOTE: @@ -62,61 +64,27 @@ sub construct_class_instance { # we need to deal with the possibility # of class immutability here, and then # get the name of the class appropriately - $class = (blessed($class) + $class = (ref($class) ? ($class->is_immutable ? $class->get_mutable_metaclass_name() - : blessed($class)) + : ref($class)) : $class); # now create the metaclass my $meta; if ($class eq 'Class::MOP::Class') { - no strict 'refs'; - $meta = bless { - # inherited from Class::MOP::Package - '$!package' => $package_name, - - # NOTE: - # since the following attributes will - # actually be loaded from the symbol - # table, and actually bypass the instance - # entirely, we can just leave these things - # listed here for reference, because they - # should not actually have a value associated - # with the slot. - '%!namespace' => \undef, - # inherited from Class::MOP::Module - '$!version' => \undef, - '$!authority' => \undef, - # defined in Class::MOP::Class - '@!superclasses' => \undef, - - '%!methods' => {}, - '%!attributes' => {}, - '$!attribute_metaclass' => $options{'attribute_metaclass'} || 'Class::MOP::Attribute', - '$!method_metaclass' => $options{'method_metaclass'} || 'Class::MOP::Method', - '$!instance_metaclass' => $options{'instance_metaclass'} || 'Class::MOP::Instance', - - ## uber-private variables - # NOTE: - # this starts out as undef so that - # we can tell the first time the - # methods are fetched - # - SL - '$!_package_cache_flag' => undef, - '$!_meta_instance' => undef, - } => $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) + $meta = $class->meta->construct_instance($options) } # and check the metaclass compatibility - $meta->check_metaclass_compatability(); + $meta->check_metaclass_compatibility(); Class::MOP::store_metaclass_by_name($package_name, $meta); @@ -128,7 +96,45 @@ sub construct_class_instance { $meta; } -sub reset_package_cache_flag { (shift)->{'$!_package_cache_flag'} = undef } +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: @@ -137,41 +143,42 @@ sub update_package_cache_flag { # 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); + $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name); } -sub check_metaclass_compatability { +sub check_metaclass_compatibility { my $self = shift; # this is always okay ... - return if blessed($self) eq 'Class::MOP::Class' && + 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 $class_name (@class_list) { - my $meta = Class::MOP::get_metaclass_by_name($class_name) || next; + 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 $meta_type = ($meta->is_immutable - ? $meta->get_mutable_metaclass_name() - : blessed($meta)); + my $super_meta_type + = $super_meta->is_immutable + ? $super_meta->get_mutable_metaclass_name() + : ref($super_meta); - ($self->isa($meta_type)) - || confess $self->name . "->meta => (" . (blessed($self)) . ")" . + ($self->isa($super_meta_type)) + || confess $self->name . "->meta => (" . (ref($self)) . ")" . " is not compatible with the " . - $class_name . "->meta => (" . ($meta_type) . ")"; + $superclass_name . "->meta => (" . ($super_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) . ")" . + # 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 " . - $class_name . "->meta => (" . ($meta->instance_metaclass) . ")"; + $superclass_name . "->meta->instance_metaclass => (" . ($super_meta->instance_metaclass) . ")"; } } @@ -194,7 +201,7 @@ sub check_metaclass_compatability { sub is_anon_class { my $self = shift; no warnings 'uninitialized'; - $self->name =~ /^$ANON_CLASS_PREFIX/ ? 1 : 0; + $self->name =~ /^$ANON_CLASS_PREFIX/; } sub create_anon_class { @@ -211,8 +218,19 @@ sub check_metaclass_compatability { # 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}) { @@ -226,18 +244,13 @@ sub check_metaclass_compatability { # creating classes with MOP ... sub create { - my $class = shift; - my $package_name = shift; + my ( $class, @args ) = @_; - (defined $package_name && $package_name) - || confess "You must pass a package name"; + unshift @args, 'package' if @args % 2 == 1; - (scalar @_ % 2 == 0) - || confess "You much pass all parameters as name => value pairs " . - "(I found an uneven number of params in \@_)"; + my (%options) = @args; + my $package_name = $options{package}; - my (%options) = @_; - (ref $options{superclasses} eq 'ARRAY') || confess "You must pass an ARRAY ref of superclasses" if exists $options{superclasses}; @@ -247,22 +260,25 @@ sub create { if exists $options{attributes}; (ref $options{methods} eq 'HASH') - || confess "You must pass an HASH ref of methods" + || confess "You must pass a HASH ref of methods" if exists $options{methods}; - my $code = "package $package_name;"; - $code .= "\$$package_name\:\:VERSION = '" . $options{version} . "';" - if exists $options{version}; - $code .= "\$$package_name\:\:AUTHORITY = '" . $options{authority} . "';" - if exists $options{authority}; + $class->SUPER::create(%options); - eval $code; - confess "creation of $package_name failed : $@" if $@; - - my $meta = $class->initialize($package_name); + 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 { - $class->initialize(blessed($_[0]) || $_[0]); + $class->initialize(ref($_[0]) || $_[0]); }); $meta->superclasses(@{$options{superclasses}}) @@ -291,63 +307,17 @@ sub create { # all these attribute readers will be bootstrapped # away in the Class::MOP bootstrap section -sub get_attribute_map { $_[0]->{'%!attributes'} } -sub attribute_metaclass { $_[0]->{'$!attribute_metaclass'} } -sub method_metaclass { $_[0]->{'$!method_metaclass'} } -sub instance_metaclass { $_[0]->{'$!instance_metaclass'} } - -# FIXME: -# this is a prime canidate for conversion to XS -sub get_method_map { - my $self = shift; - - if (defined $self->{'$!_package_cache_flag'} && - $self->{'$!_package_cache_flag'} == Class::MOP::check_package_cache_flag($self->name)) { - return $self->{'%!methods'}; - } - - my $map = $self->{'%!methods'}; - - my $class_name = $self->name; - my $method_metaclass = $self->method_metaclass; - - my %all_code = $self->get_all_package_symbols('CODE'); - - foreach my $symbol (keys %all_code) { - my $code = $all_code{$symbol}; - - next if exists $map->{$symbol} && - defined $map->{$symbol} && - $map->{$symbol}->body == $code; - - my ($pkg, $name) = Class::MOP::get_code_info($code); - - # NOTE: - # in 5.10 constant.pm the constants show up - # as being in the right package, but in pre-5.10 - # they show up as constant::__ANON__ so we - # make an exception here to be sure that things - # work as expected in both. - # - SL - unless ($pkg eq 'constant' && $name eq '__ANON__') { - next if ($pkg || '') ne $class_name || - (($name || '') ne '__ANON__' && ($pkg || '') ne $class_name); - } - - $map->{$symbol} = $method_metaclass->wrap( - $code, - package_name => $class_name, - name => $symbol, - ); - } - - return $map; -} +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 $class = shift; + # NOTE: # we need to protect the integrity of the # Class::MOP::Class singletons here, so we @@ -359,11 +329,12 @@ sub new_object { } sub construct_instance { - my ($class, %params) = @_; + 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()) { - $attr->initialize_instance_slot($meta_instance, $instance, \%params); + $attr->initialize_instance_slot($meta_instance, $instance, $params); } # NOTE: # this will only work for a HASH instance type @@ -383,31 +354,29 @@ sub construct_instance { sub get_meta_instance { my $self = shift; - # NOTE: - # just about any fiddling with @ISA or - # any fiddling with attributes will - # also fiddle with the symbol table - # and therefore invalidate the package - # cache, in which case we should blow - # away the meta-instance cache. Of course - # this will invalidate it more often then - # is probably needed, but better safe - # then sorry. - # - SL - $self->{'$!_meta_instance'} = undef - if defined $self->{'$!_package_cache_flag'} && - $self->{'$!_package_cache_flag'} == Class::MOP::check_package_cache_flag($self->name); - $self->{'$!_meta_instance'} ||= $self->instance_metaclass->new( - $self, - $self->compute_all_applicable_attributes() + $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 $instance = shift; (blessed($instance) && $instance->isa($class->name)) - || confess "You must pass an instance ($instance) of the metaclass (" . $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 @@ -419,7 +388,7 @@ sub clone_object { sub clone_instance { my ($class, $instance, %params) = @_; (blessed($instance)) - || confess "You can only clone instances, \$self is not a 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()) { @@ -442,7 +411,7 @@ sub rebless_instance { $old_metaclass = $instance->meta; } else { - $old_metaclass = $self->initialize(blessed($instance)); + $old_metaclass = $self->initialize(ref($instance)); } my $meta_instance = $self->get_meta_instance(); @@ -451,7 +420,8 @@ sub rebless_instance { || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't."; # rebless! - $meta_instance->rebless_instance_structure($instance, $self); + # 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) ) { @@ -475,63 +445,79 @@ sub rebless_instance { # Inheritance sub superclasses { - my $self = shift; + my $self = shift; + my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' }; if (@_) { my @supers = @_; - @{$self->get_package_symbol('@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_compatability(); + + $self->check_metaclass_compatibility(); + $self->update_meta_instance_dependencies(); } - @{$self->get_package_symbol('@ISA')}; + @{$self->get_package_symbol($var_spec)}; } sub subclasses { my $self = shift; my $super_class = $self->name; - my @derived_classes; - - my $find_derived_classes; - $find_derived_classes = sub { - my ($outer_class) = @_; - my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} }; + if ( Class::MOP::HAVE_ISAREV() ) { + return @{ $super_class->mro::get_isarev() }; + } else { + my @derived_classes; - SYMBOL: - for my $symbol ( keys %$symbol_table_hashref ) { - next SYMBOL if $symbol !~ /\A (\w+):: \z/x; - my $inner_class = $1; + my $find_derived_classes; + $find_derived_classes = sub { + my ($outer_class) = @_; - next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER' + my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} }; - my $class = - $outer_class - ? "${outer_class}::$inner_class" - : $inner_class; + SYMBOL: + for my $symbol ( keys %$symbol_table_hashref ) { + next SYMBOL if $symbol !~ /\A (\w+):: \z/x; + my $inner_class = $1; - if ( $class->isa($super_class) and $class ne $super_class ) { - push @derived_classes, $class; - } + next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER' - next SYMBOL if $class eq 'main'; # skip 'main::*' + my $class = + $outer_class + ? "${outer_class}::$inner_class" + : $inner_class; - $find_derived_classes->($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); + my $root_class = q{}; + $find_derived_classes->($root_class); - undef $find_derived_classes; + undef $find_derived_classes; - @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes; + @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes; - return @derived_classes; + return @derived_classes; + } } @@ -575,6 +561,18 @@ sub class_precedence_list { ## 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) @@ -583,11 +581,7 @@ sub add_method { my $body; if (blessed($method)) { $body = $method->body; - if ($method->package_name ne $self->name && - $method->name ne $method_name) { - warn "Hello there, got somethig for you." - . " Method says " . $method->package_name . " " . $method->name - . " Class says " . $self->name . " " . $method_name; + if ($method->package_name ne $self->name) { $method = $method->clone( package_name => $self->name, name => $method_name @@ -596,27 +590,27 @@ sub add_method { } else { $body = $method; - ('CODE' eq ref($body)) - || confess "Your code block must be a CODE reference"; - $method = $self->method_metaclass->wrap( - $body => ( - package_name => $self->name, - name => $method_name - ) - ); + $method = $self->wrap_method_body( body => $body, name => $method_name ); } - $self->get_method_map->{$method_name} = $method; + + $method->attach_to_class($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); - $self->add_package_symbol("&${method_name}" => + $self->add_package_symbol( + { sigil => '&', type => 'CODE', name => $method_name }, Class::MOP::subname($full_method_name => $body) ); - $self->update_package_cache_flag; } { 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 ... @@ -625,16 +619,16 @@ sub add_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 inheritance hierarchy for class " . $self->name; + || confess "The method '$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 - $method = Class::MOP::Method::Wrapped->wrap($method); + $method = $wrapped_metaclass->wrap($method); } else { # now make sure we wrap it properly - $method = Class::MOP::Method::Wrapped->wrap($method) - unless $method->isa('Class::MOP::Method::Wrapped'); + $method = $wrapped_metaclass->wrap($method) + unless $method->isa($wrapped_metaclass); } $self->add_method($method_name => $method); return $method; @@ -685,16 +679,9 @@ sub add_method { } sub alias_method { - my ($self, $method_name, $method) = @_; - (defined $method_name && $method_name) - || confess "You must define a method name"; - - my $body = (blessed($method) ? $method->body : $method); - ('CODE' eq ref($body)) - || confess "Your code block must be a CODE reference"; + my $self = shift; - $self->add_package_symbol("&${method_name}" => $body); - $self->update_package_cache_flag; + $self->add_method(@_); } sub has_method { @@ -702,8 +689,7 @@ sub has_method { (defined $method_name && $method_name) || confess "You must define a method name"; - return 0 unless exists $self->get_method_map->{$method_name}; - return 1; + exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name}; } sub get_method { @@ -711,13 +697,7 @@ sub get_method { (defined $method_name && $method_name) || confess "You must define a method name"; - # NOTE: - # I don't really need this here, because - # if the method_map is missing a key it - # will just return undef for me now - # return unless $self->has_method($method_name); - - return $self->get_method_map->{$method_name}; + return $self->{methods}{$method_name} || $self->get_method_map->{$method_name}; } sub remove_method { @@ -727,9 +707,13 @@ sub remove_method { my $removed_method = delete $self->get_method_map->{$method_name}; - $self->remove_package_symbol("&${method_name}"); - - $self->update_package_cache_flag; + $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; } @@ -752,23 +736,27 @@ sub find_method_by_name { 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 (@methods, %seen_method); - 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 @methods; + my %uniq; + grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods; } sub find_all_methods_by_name { @@ -823,19 +811,91 @@ sub add_attribute { # name here so that we can properly detach # the old attr object, and remove any # accessors it would have generated - $self->remove_attribute($attribute->name) - if $self->has_attribute($attribute->name); + if ( $self->has_attribute($attribute->name) ) { + $self->remove_attribute($attribute->name); + } else { + $self->invalidate_meta_instances(); + } # then onto installing the new accessors - $attribute->install_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 { @@ -856,6 +916,7 @@ sub remove_attribute { 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 $removed_attribute; @@ -866,19 +927,14 @@ sub get_attribute_list { keys %{$self->get_attribute_map}; } +sub get_all_attributes { + shift->compute_all_applicable_attributes(@_); +} + sub compute_all_applicable_attributes { my $self = shift; - my (@attrs, %seen_attr); - 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 @attrs; + my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa; + return values %attrs; } sub find_attribute_by_name { @@ -892,96 +948,101 @@ sub find_attribute_by_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 1; +} + ## Class closing sub is_mutable { 1 } sub is_immutable { 0 } -# NOTE: -# Why I changed this (groditi) -# - One Metaclass may have many Classes through many Metaclass instances -# - One Metaclass should only have one Immutable Transformer instance -# - Each Class may have different Immutabilizing options -# - Therefore each Metaclass instance may have different Immutabilizing options -# - We need to store one Immutable Transformer instance per Metaclass -# - We need to store one set of Immutable Transformer options per Class -# - Upon make_mutable we may delete the Immutabilizing options -# - We could clean the immutable Transformer instance when there is no more -# immutable Classes of that type, but we can also keep it in case -# another class with this same Metaclass becomes immutable. It is a case -# of trading of storing an instance to avoid unnecessary instantiations of -# Immutable Transformers. You may view this as a memory leak, however -# Because we have few Metaclasses, in practice it seems acceptable -# - To allow Immutable Transformers instances to be cleaned up we could weaken -# the reference stored in $IMMUTABLE_TRANSFORMERS{$class} and ||= should DWIM +sub immutable_transformer { $_[0]->{immutable_transformer} } +sub _set_immutable_transformer { $_[0]->{immutable_transformer} = $_[1] } { - my %IMMUTABLE_TRANSFORMERS; - my %IMMUTABLE_OPTIONS; + 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; - my %options = @_; - my $class = blessed $self || $self; - $IMMUTABLE_TRANSFORMERS{$class} ||= $self->create_immutable_transformer; - my $transformer = $IMMUTABLE_TRANSFORMERS{$class}; + return if $self->is_immutable; - $transformer->make_metaclass_immutable($self, \%options); - $IMMUTABLE_OPTIONS{$self->name} = - { %options, IMMUTABLE_TRANSFORMER => $transformer }; + my $transformer = $self->immutable_transformer + || Class::MOP::Immutable->new( + $self, + %Default_Immutable_Options, + @_ + ); - if( exists $options{debug} && $options{debug} ){ - print STDERR "# of Metaclass options: ", keys %IMMUTABLE_OPTIONS; - print STDERR "# of Immutable transformers: ", keys %IMMUTABLE_TRANSFORMERS; - } - - 1; - } + $self->_set_immutable_transformer($transformer); - sub make_mutable{ - my $self = shift; - return if $self->is_mutable; - my $options = delete $IMMUTABLE_OPTIONS{$self->name}; - confess "unable to find immutabilizing options" unless ref $options; - my $transformer = delete $options->{IMMUTABLE_TRANSFORMER}; - $transformer->make_metaclass_mutable($self, $options); - 1; + $transformer->make_metaclass_immutable; } } -sub create_immutable_transformer { +sub make_mutable { my $self = shift; - my $class = Class::MOP::Immutable->new($self, { - 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', - linearized_isa => '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'; - goto $original->body; - }, - }, - }); - return $class; + + return if $self->is_mutable; + + $self->immutable_transformer->make_metaclass_mutable; } 1; @@ -1002,587 +1063,577 @@ Class::MOP::Class - Class Meta Object # use this for introspection ... # add a method to Foo ... - Foo->meta->add_method('bar' => sub { ... }) + Foo->meta->add_method( 'bar' => sub {...} ) - # get a list of all the classes searched - # the method dispatcher in the correct order - Foo->meta->class_precedence_list() + # get a list of all the classes searched + # the method dispatcher in the correct order + Foo->meta->class_precedence_list() - # remove a method from Foo - Foo->meta->remove_method('bar'); + # remove a method from Foo + Foo->meta->remove_method('bar'); # or use this to actually create classes ... - Class::MOP::Class->create('Bar' => ( - version => '0.01', - superclasses => [ 'Foo' ], - attributes => [ - Class::MOP:::Attribute->new('$bar'), - Class::MOP:::Attribute->new('$baz'), - ], - methods => { - calculate_bar => sub { ... }, - construct_baz => sub { ... } - } - )); + Class::MOP::Class->create( + 'Bar' => ( + version => '0.01', + superclasses => ['Foo'], + attributes => [ + Class::MOP:: : Attribute->new('$bar'), + Class::MOP:: : Attribute->new('$baz'), + ], + methods => { + calculate_bar => sub {...}, + construct_baz => sub {...} + } + ) + ); =head1 DESCRIPTION -This is the largest and currently most complex part of the Perl 5 -meta-object protocol. It controls the introspection and -manipulation of Perl 5 classes (and it can create them too). The +The Class Protocol is the largest and most complex part of the +Class::MOP meta-object protocol. It controls the introspection and +manipulation of Perl 5 classes, and it can create them as well. The best way to understand what this module can do, is to read the -documentation for each of it's methods. +documentation for each of its methods. + +=head1 INHERITANCE + +C is a subclass of L. =head1 METHODS -=head2 Self Introspection +=head2 Class construction + +These methods all create new C objects. These +objects can represent existing classes, or they can be used to create +new classes from scratch. + +The metaclass object for a given class is a singleton. If you attempt +to create a metaclass for the same class twice, you will just get the +existing object. =over 4 -=item B +=item B<< Class::MOP::Class->create($package_name, %options) >> -This will return a B instance which is related -to this class. Thereby allowing B to actually -introspect itself. +This method creates a new C object with the given +package name. It accepts a number of options. -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. +=over 8 -=back +=item * version -=head2 Class construction +An optional version number for the newly created package. -These methods will handle creating B objects, -which can be used to both create new classes, and analyze -pre-existing classes. +=item * authority -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. +An optional authority for the newly created package. -=over 4 +=item * superclasses -=item B ?$version, - authority =E ?$authority, - superclasses =E ?@superclasses, - methods =E ?%methods, - attributes =E ?%attributes)> +An optional array reference of superclass names. -This returns a B object, bringing the specified -C<$package_name> into existence and adding any of the C<$version>, -C<$authority>, C<@superclasses>, C<%methods> and C<%attributes> to -it. +=item * methods -=item B ?@superclasses, - methods =E ?%methods, - attributes =E ?%attributes)> +An optional hash reference of methods for the class. The keys of the +hash reference are method names, and values are subroutine references. -This will create an anonymous class, it works much like C but -it does not need a C<$package_name>. Instead it will create a suitably -unique package name for you to stash things into. +=item * attributes -On very important distinction is that anon classes are destroyed once -the metaclass they are attached to goes out of scope. In the DESTROY -method, the created package will be removed from the symbol table. +An optional array reference of attributes. -It is also worth noting that any instances created with an anon-class -will keep a special reference to the anon-meta which will prevent the -anon-class from going out of scope until all instances of it have also -been destroyed. This however only works for HASH based instance types, -as we use a special reserved slot (C<__MOP__>) to store this. +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. -=item B +=back -This initializes and returns returns a B object -for a given a C<$package_name>. +=item B<< Class::MOP::Class->create_anon_class(%options) >> -=item B +This method works just like C<< Class::MOP::Class->create >> but it +creates an "anonymous" class. In fact, the class does have a name, but +that name is a unique name generated internally by this module. -This removes the old metaclass, and creates a new one in it's place. -Do B use this unless you really know what you are doing, it could -very easily make a very large mess of your program. +It accepts the same C, C, and C +parameters that C accepts. -=item B +Anonymous classes are destroyed once the metaclass they are attached +to goes out of scope, and will be removed from Perl's internal symbol +table. -This will construct an instance of B, it is -here so that we can actually "tie the knot" for B -to use C once all the bootstrapping is done. This -method is used internally by C and should never be called -from outside of that method really. +All instances of an anonymous class keep a special reference to the +metaclass object, which prevents the metaclass from going out of scope +while any instances exist. -=item B +This only works if the instance if based on a hash reference, however. -This method is called as the very last thing in the -C method. This will check that the -metaclass you are creating is compatible with the metaclasses of all -your ancestors. For more inforamtion about metaclass compatibility -see the C section in L. +=item B<< Class::MOP::Class->initialize($package_name, %options) >> -=item B +This method will initialize a C object for the +named package. Unlike C, this method I create a new +class. -This will reset the package cache flag for this particular metaclass -it is basically the value of the C -function. This is very rarely needed from outside of C -but in some cases you might want to use it, so it is here. +The purpose of this method is to retrieve a C +object for introspecting an existing class. -=item B +If an existing C object exists for the named +package, it will be returned, and any options provided will be +ignored! -Clears the package cache flag to announce to the internals that we need -to rebuild the method map. +If the object does not yet exist, it will be created. + +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 - -Returns the class name of the instance metaclass, see L -for more information on the instance metaclasses. +=item B<< $metaclass->clone_object($instance, %params) >> -=item B +This method clones an existing object instance. Any parameters you +provide are will override existing attribute values in the object. -Returns an instance of L to be used in the construction -of a new instance of the class. +This is a convenience method for cloning an object instance, then +blessing it into the appropriate package. -=item B +You could implement a clone method in your class, using this method: -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) = @_; - $class->meta->new_object(%params); + sub clone { + my ($self, %params) = @_; + $self->meta->clone_object($self, %params); } -=item B +=item B<< $metaclass->rebless_instance($instance, %params) >> -This method is used to construct an instance structure suitable for -C-ing into your package of choice. It works in conjunction -with the Attribute protocol to collect all applicable attributes. +This method changes the class of C<$instance> to the metaclass's class. -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. +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. -=item B +=item B<< $metaclass->new_object(%params) >> -This is a convience method for cloning an object instance, then -blessing it into the appropriate package. This method will call -C, which performs a shallow copy of the object, -see that methods documentation for more details. Ideally your -class would call a C this method like so: +This method is used to create a new object of the metaclass's +class. Any parameters you provide are used to initialize the +instance's attributes. - sub MyClass::clone { - my ($self, %param) = @_; - $self->meta->clone_object($self, %params); - } - -=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. +=item B<< $metaclass->instance_metaclass >> -The cloned structure returned is (like with C) an -unCed HASH reference, it is your responsibility to then bless -this cloned structure into the right class (which C will -do for you). +Returns the class name of the instance metaclass, see +L for more information on the instance +metaclasses. -As of 0.11, this method will clone the C<$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. +=item B<< $metaclass->get_meta_instance >> -=item B - -This will change the class of C<$instance> to the class of the invoking -C. You may only rebless the instance to a subclass of -itself. You may pass in optional C<%params> which are like constructor -params and will override anything already defined in the instance. +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. +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 is a C created anon class. +This returns true if the class was created by calling C<< +Class::MOP::Class->create_anon_class >>. -=item B +=item B<< $metaclass->is_mutable >> This returns true if the class is still mutable. -=item B +=item B<< $metaclass->is_immutable >> This returns true if the class has been made immutable. +=item B<< $metaclass->is_pristine >> + +A class is I pristine if it has non-inherited attributes or if it +has any generated methods. + =back =head2 Inheritance Relationships =over 4 -=item B +=item B<< $metaclass->superclasses(@superclasses) >> + +This is a read-write accessor which represents the superclass +relationships of the metaclass's class. -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 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 +=item B<< $metaclass->linearized_isa >> -This returns a list based on C but with all +This returns a list based on C but with all duplicates removed. -=item B +=item B<< $metaclass->subclasses >> -This returns a list of subclasses for this class. +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) >> -Returns a HASH ref of name to CODE reference mapping for this class. +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 +=item B<< $metaclass->has_method($method_name) >> -Returns the class name of the method metaclass, see L -for more information on the method metaclasses. +Returns a boolean indicating whether or not the class defines the +named method. It does not include methods inherited from parent +classes. -=item B +=item B<< $metaclass->get_method_map >> -This will take a C<$method_name> and CODE reference to that -C<$method> and install it into the class's package. +Returns a hash reference representing the methods defined in this +class. The keys are method names and the values are +L objects. -B: -This does absolutely nothing special to C<$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<< $metaclass->get_method_list >> -=item B +This will return a list of method I for all methods defined in +this class. -This will take a C<$method_name> and CODE reference to that -C<$method> and alias the method into the class's package. +=item B<< $metaclass->get_all_methods >> -B: -Unlike C, this will B try to name the -C<$method> using B, it only aliases the method in -the class's package. +This will traverse the inheritance hierarchy and return a list of all +the L objects for this class and its parents. -=item B +=item B<< $metaclass->find_method_by_name($method_name) >> -This just provides a simple way to check if the class implements -a specific C<$method_name>. It will I however, attempt to check -if the class inherits the method (use C for that). +This will return a L for the specified +C<$method_name>. If the class does not have the specified method, it +returns C -This will correctly handle functions defined outside of the package -that use a fully qualified name (C). +Unlike C, this method I look for the named method in +superclasses. -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. +=item B<< $metaclass->get_all_method_names >> -This will attempt to correctly ignore functions imported from other -packages using B. It breaks down if the function imported -is an C<__ANON__> sub (such as with C), which very well -may be a valid method being applied to the class. +This will return a list of method I for all of this class's +methods, including inherited methods. -In short, this method cannot always be trusted to determine if the -C<$method_name> is actually a method. However, it will DWIM about -90% of the time, so it's a small trade off I think. +=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 Class::MOP::Method instance related to the specified -C<$method_name>, or return undef if that method does not exist. +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. -The Class::MOP::Method is codifiable, so you can use it like a normal -CODE reference, see L for more information. +The list of methods is distinct. -=item B +=item B<< $metaclass->find_next_method_by_name($method_name) >> -This will return a CODE reference of the specified C<$method_name>, -or return undef if that method does not exist. +This method returns the first method in any superclass matching the +given name. It is effectively the method that C +would dispatch to. -Unlike C this will also look in the superclasses. +=item B<< $metaclass->add_method($method_name, $method) >> -=item B +This method takes a method name and a subroutine reference, and adds +the method to the class. -This will attempt to remove a given C<$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. +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. -=item B +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). -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. +=item B<< $metaclass->remove_method($method_name) >> -=item B +Remove the named method from the class. This method returns the +L object for the method. -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. +=back -=item B +=head2 Attribute introspection and creation -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. +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. -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. +=over 4 -=item B +=item B<< $metaclass->get_attribute($attribute_name) >> -This will return the first method to match a given C<$method_name> in -the superclasses, this is basically equivalent to calling -C, but it can be dispatched at runtime. +This will return a L for the specified +C<$attribute_name>. If the class does not have the specified +attribute, it returns C -=back +=item B<< $metaclass->has_attribute($attribute_name) >> -=head2 Method Modifiers +Returns a boolean indicating whether or not the class defines the +named attribute. It does not include attributes inherited from parent +classes. -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. +=item B<< $metaclass->get_attribute_map >> -=head3 How method modifiers work? +Returns a hash reference representing the attributes defined in this +class. The keys are attribute names and the values are +L objects. -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: +=item B<< $metaclass->get_attribute_list >> - before 2 - before 1 - around 2 - around 1 - primary - after 1 - after 2 +This will return a list of attributes I for all attributes +defined in this class. -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>. +=item B<< $metaclass->get_all_attributes >> -=head3 What is the performance impact? +This will traverse the inheritance hierarchy and return a list of all +the L objects for this class and its parents. -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. +This method can also be called as C. -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. +=item B<< $metaclass->find_attribute_by_name($attribute_name) >> -All this said, my benchmarks have indicated the following: +This will return a L for the specified +C<$attribute_name>. If the class does not have the specified +attribute, it returns C - 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 +Unlike C, this attribute I look for the named +attribute in superclasses. -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. +=item B<< $metaclass->add_attribute(...) >> -=over 4 +This method accepts either an existing L +object, or parameters suitable for passing to that class's C +method. + +The attribute provided will be added to the class. -=item B +Any accessor methods defined by the attribute will be added to the +class when the attribute is added. -This will wrap the method at C<$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. +If an attribute of the same name already exists, the old attribute +will be removed first. -=item B +=item B<< $metaclass->remove_attribute($attribute_name) >> -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. +This will remove the named attribute from the class, and +L object. -=item B +Removing an attribute also removes any accessor methods defined by the +attribute. -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. +However, note that removing an attribute will only affect I +object instances created for this class, not existing instances. + +=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 Attributes +=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. -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. +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 +=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. -Returns the class name of the attribute metaclass, see L -for more information on the attribute metaclasses. +Details of how immutabilization works are in L +documentation. -=item B +=item B<< $metaclass->make_mutable >> -This returns a HASH ref of name to attribute meta-object mapping. +Calling this method reverse the immutabilization transformation. -=item B +=item B<< $metaclass->immutable_transformer >> -This stores the C<$attribute_meta_object> (or creates one from the -C<$attribute_name> and C<%attribute_spec>) in the B -instance associated with the given class. Unlike methods, attributes -within the MOP are stored as meta-information only. They will be used -later to construct instances from (see C above). -More details about the attribute meta-objects can be found in the -L or the L -section. +If the class has been made immutable previously, this returns the +L object that was created to do the +transformation. -It should be noted that any accessor, reader/writer or predicate -methods which the C<$attribute_meta_object> has will be installed -into the class at this time. +If the class was never made immutable, this method will die. -B -If an attribute already exists for C<$attribute_name>, the old one -will be removed (as well as removing all it's accessors), and then -the new one added. +=back -=item B +=head2 Method Modifiers -Checks to see if this class has an attribute by the name of -C<$attribute_name> and returns a boolean. +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. -=item B +A class can modify its own methods, as well as methods defined in +parent classes. -Returns the attribute meta-object associated with C<$attribute_name>, -if none is found, it will return undef. +=head3 How method modifiers work? -=item B +Method modifiers work by wrapping the original method and then +replacing it in the class's symbol table. The wrappers will handle +calling all the modifiers in the appropriate order and preserving the +calling context for the original method. -This will remove the attribute meta-object stored at -C<$attribute_name>, then return the removed attribute meta-object. +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). -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. +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. -It should be noted that any accessor, reader/writer or predicate -methods which the attribute meta-object stored at C<$attribute_name> -has will be removed from the class at this time. This B make -these attributes somewhat inaccessable in previously created -instances. But if you are crazy enough to do this at runtime, then -you are crazy enough to deal with something like this :). +Of course if you have more complex needs, you can use the C +modifier which allows you to change both the parameters passed to the +wrapped method, as well as its return value. -=item B +Before and around modifiers are called in last-defined-first-called +order, while after modifiers are called in first-defined-first-called +order. So the call tree might looks something like this: -This returns a list of attribute names which are defined in the local -class. If you want a list of all applicable attributes for a class, -use the C method. + before 2 + before 1 + around 2 + around 1 + primary + around 1 + around 2 + after 1 + after 2 -=item B +=head3 What is the performance impact? -This will traverse the inheritance heirachy and return a list of all -the applicable attributes for this class. It does not construct a -HASH reference like C because all -that same information is discoverable through the attribute -meta-object itself. +Of course there is a performance cost associated with method +modifiers, but we have made every effort to make that cost directly +proportional to the number of modifier features you utilize. -=item B +The wrapping method does it's best to B do as much work as it +absolutely needs to. In order to do this we have moved some of the +performance costs to set-up time, where they are easier to amortize. -This method will traverse the inheritance heirachy and find the -first attribute whose name matches C<$attr_name>, then return it. -It will return undef if nothing is found. +All this said, our benchmarks have indicated the following: -=back + 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 -=head2 Class Immutability +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. + +The return value of the modifier will be ignored. + +=item B<< $metaclass->add_after_method_modifier($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 wrapped methods exits, the modifier will be called. + +The return value of the modifier will be ignored. -This method will invoke a tranforamtion upon the class which will -make it immutable. Details of this transformation can be found in -the L documentation. +=item B<< $metaclass->add_around_method_modifier($method_name, $code) >> -=item B +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 -This method will reverse tranforamtion upon the class which -made it immutable. +=item B<< Class::MOP::Class->meta >> -=item B +This will return a L instance for this class. -Create a transformer suitable for making this class immutable +It should also be noted that L will actually bootstrap +this module by installing a number of attribute meta-objects into its +metaclass. =back @@ -1592,7 +1643,7 @@ Stevan Little Estevan@iinteractive.comE =head1 COPYRIGHT AND LICENSE -Copyright 2006-2008 by Infinity Interactive, Inc. +Copyright 2006-2009 by Infinity Interactive, Inc. L