X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FClass%2FMOP%2FClass.pm;h=0c432307d64f1d184839e5c4e264491bd3918cd3;hb=6e1c8b63d87c6e1d8e84e15cc2c1f5336780515b;hp=6ebd6d121bcd1765f70e37079e64a4f4f8f8f90f;hpb=2e41896ef928bb97cd490b03cd77f0280d802384;p=gitmo%2FClass-MOP.git diff --git a/lib/Class/MOP/Class.pm b/lib/Class/MOP/Class.pm index 6ebd6d1..0c43230 100644 --- a/lib/Class/MOP/Class.pm +++ b/lib/Class/MOP/Class.pm @@ -4,70 +4,271 @@ 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 = '0.02'; +use Carp 'confess'; +use Scalar::Util 'blessed', 'weaken'; -# Self-introspection +our $VERSION = '0.63'; +our $AUTHORITY = 'cpan:STEVAN'; -sub meta { $_[0]->initialize($_[0]) } +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, @_); +} + +sub reinitialize { + my $class = shift; + my $package_name = shift; + (defined $package_name && $package_name && !blessed($package_name)) + || confess "You must pass a package name and it cannot be blessed"; + Class::MOP::remove_metaclass_by_name($package_name); + $class->construct_class_instance('package' => $package_name, @_); +} + +# NOTE: (meta-circularity) +# this is a special form of &construct_instance +# (see below), which is used to construct class +# meta-object instances for any Class::MOP::* +# class. All other classes will use the more +# normal &construct_instance. +sub construct_class_instance { + my $class = shift; + my %options = @_; + my $package_name = $options{'package'}; + (defined $package_name && $package_name) + || confess "You must pass a package name"; + # NOTE: + # return the metaclass if we have it cached, + # and it is still defined (it has not been + # reaped by DESTROY yet, which can happen + # annoyingly enough during global destruction) + + 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 + $class = (blessed($class) + ? ($class->is_immutable + ? $class->get_mutable_metaclass_name() + : blessed($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; + } + else { + # NOTE: + # it is safe to use meta here because + # class will always be a subclass of + # Class::MOP::Class, which defines meta + $meta = $class->meta->construct_instance(%options) + } + + # and check the metaclass compatibility + $meta->check_metaclass_compatability(); + + Class::MOP::store_metaclass_by_name($package_name, $meta); + + # NOTE: + # we need to weaken any anon classes + # so that they can call DESTROY properly + Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class; + + $meta; +} + +sub reset_package_cache_flag { (shift)->{'$!_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_compatability { + my $self = shift; + + # this is always okay ... + return if blessed($self) eq 'Class::MOP::Class' && + $self->instance_metaclass eq 'Class::MOP::Instance'; + + my @class_list = $self->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; + + # NOTE: + # we need to deal with the possibility + # of class immutability here, and then + # get the name of the class appropriately + my $meta_type = ($meta->is_immutable + ? $meta->get_mutable_metaclass_name() + : blessed($meta)); + + ($self->isa($meta_type)) + || confess $self->name . "->meta => (" . (blessed($self)) . ")" . + " is not compatible with the " . + $class_name . "->meta => (" . ($meta_type) . ")"; + # NOTE: + # we also need to check that instance metaclasses + # are compatabile in the same the class. + ($self->instance_metaclass->isa($meta->instance_metaclass)) + || confess $self->name . "->meta => (" . ($self->instance_metaclass) . ")" . + " is not compatible with the " . + $class_name . "->meta => (" . ($meta->instance_metaclass) . ")"; + } +} + +## ANON classes + { - # Metaclasses are singletons, so we cache them here. - # there is no need to worry about destruction though - # because they should die only when the program dies. - # After all, do package definitions even get reaped? - my %METAS; - sub initialize { - my ($class, $package_name) = @_; - (defined $package_name && $package_name) - || confess "You must pass a package name"; - 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/ ? 1 : 0; } - - # 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, $package_name) = @_; - (defined $package_name && $package_name) - || confess "You must pass a package name"; - $class = blessed($class) || $class; - if ($class =~ /^Class::MOP::/) { - bless { - '$:pkg' => $package_name, - '%:attrs' => {} - } => $class; - } - else { - bless $class->meta->construct_instance(':pkg' => $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; + no warnings 'uninitialized'; + return unless $self->name =~ /^$ANON_CLASS_PREFIX/; + my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/); + no strict 'refs'; + foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) { + delete ${$ANON_CLASS_PREFIX . $serial_id}{$key}; } + delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'}; } + } +# creating classes with MOP ... + sub create { - my ($class, $package_name, $package_version, %options) = @_; + my $class = shift; + my $package_name = shift; + (defined $package_name && $package_name) || confess "You must pass a package name"; + + (scalar @_ % 2 == 0) + || confess "You much pass all parameters as name => value pairs " . + "(I found an uneven number of params in \@_)"; + + my (%options) = @_; + + (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 an HASH ref of methods" + if exists $options{methods}; + my $code = "package $package_name;"; - $code .= "\$$package_name\:\:VERSION = '$package_version';" - if defined $package_version; + $code .= "\$$package_name\:\:VERSION = '" . $options{version} . "';" + if exists $options{version}; + $code .= "\$$package_name\:\:AUTHORITY = '" . $options{authority} . "';" + if exists $options{authority}; + eval $code; - confess "creation of $package_name failed : $@" if $@; + confess "creation of $package_name failed : $@" if $@; + my $meta = $class->initialize($package_name); + + $meta->add_method('meta' => sub { + $class->initialize(blessed($_[0]) || $_[0]); + }); + $meta->superclasses(@{$options{superclasses}}) if exists $options{superclasses}; # NOTE: - # process attributes first, so that they can + # 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. @@ -75,114 +276,438 @@ 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; } -# Instance Construction +## Attribute readers + +# NOTE: +# 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; +} + +# Instance Construction & Cloning + +sub new_object { + my $class = shift; + # NOTE: + # we need to protect the integrity of the + # Class::MOP::Class singletons here, so we + # delegate this to &construct_class_instance + # which will deal with the singletons + return $class->construct_class_instance(@_) + if $class->name->isa('Class::MOP::Class'); + return $class->construct_instance(@_); +} sub construct_instance { my ($class, %params) = @_; - my $instance = {}; - foreach my $attr (map { $_->{attribute} } $class->compute_all_applicable_attributes()) { - # if the attr has an init_arg, use that, otherwise, - # use the attributes name itself as the init_arg - my $init_arg = $attr->has_init_arg() ? $attr->init_arg() : $attr->name; - # try to fetch the init arg from the %params ... - my $val; - $val = $params{$init_arg} if exists $params{$init_arg}; - # if nothing was in the %params, we can use the - # attribute's default value (if it has one) - $val ||= $attr->default($instance) if $attr->has_default(); - # now add this to the instance structure - $instance->{$attr->name} = $val; + 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, $instance, \%params); + } + # NOTE: + # this will only work for a HASH instance type + if ($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; } -# Informational - -sub name { $_[0]->{'$:pkg'} } -sub version { +sub get_meta_instance { my $self = shift; - no strict 'refs'; - ${$self->name . '::VERSION'}; + # 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() + ); +} + +sub clone_object { + my $class = shift; + my $instance = shift; + (blessed($instance) && $instance->isa($class->name)) + || confess "You must pass an instance ($instance) of the metaclass (" . $class->name . ")"; + # NOTE: + # we need to protect the integrity of the + # Class::MOP::Class singletons here, they + # should not be cloned. + return $instance if $instance->isa('Class::MOP::Class'); + $class->clone_instance($instance, @_); +} + +sub clone_instance { + my ($class, $instance, %params) = @_; + (blessed($instance)) + || confess "You can only clone instances, \$self is not a blessed instance"; + my $meta_instance = $class->get_meta_instance(); + my $clone = $meta_instance->clone_instance($instance); + foreach my $attr ($class->compute_all_applicable_attributes()) { + if ( defined( my $init_arg = $attr->init_arg ) ) { + if (exists $params{$init_arg}) { + $attr->set_value($clone, $params{$init_arg}); + } + } + } + return $clone; +} + +sub rebless_instance { + my ($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 = $self->initialize(blessed($instance)); + } + + my $meta_instance = $self->get_meta_instance(); + + $self->name->isa($old_metaclass->name) + || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't."; + + # rebless! + $meta_instance->rebless_instance_structure($instance, $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: + # 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->name . '::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}::"} }; + + 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; +} + + +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() + } $self->superclasses() + ); + } } ## Methods -# un-used right now ... -sub method_metaclass { 'Class::MOP::Method' } - sub add_method { my ($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->name ne $method_name) { + warn "Hello there, got somethig for you." + . " Method says " . $method->package_name . " " . $method->name + . " Class says " . $self->name . " " . $method_name; + $method = $method->clone( + package_name => $self->name, + name => $method_name + ) if $method->can('clone'); + } + } + 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 + ) + ); + } + $self->get_method_map->{$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) + ); + $self->update_package_cache_flag; } { + my $fetch_and_prepare_method = sub { + my ($self, $method_name) = @_; + # fetch it locally + my $method = $self->get_method($method_name); + # if we dont have local ... + unless ($method) { + # try to find the next method + $method = $self->find_next_method_by_name($method_name); + # die if it does not exist + (defined $method) + || confess "The method '$method_name' is not found in the inheritance hierarchy for class " . $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); + } + else { + # now make sure we wrap it properly + $method = Class::MOP::Method::Wrapped->wrap($method) + unless $method->isa('Class::MOP::Method::Wrapped'); + } + $self->add_method($method_name => $method); + return $method; + }; - ## 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, $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"; + + $self->add_package_symbol( + { sigil => '&', type => 'CODE', name => $method_name } => $body + ); + $self->update_package_cache_flag; +} + +sub has_method { + my ($self, $method_name) = @_; + (defined $method_name && $method_name) + || confess "You must define a method name"; + + return 0 unless exists $self->get_method_map->{$method_name}; + return 1; } sub get_method { @@ -190,50 +715,60 @@ 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 + # 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}; } 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); + $self->remove_package_symbol( + { sigil => '&', type => 'CODE', name => $method_name } + ); - no strict 'refs'; - delete ${$self->name . '::'}{$method_name} - if defined $removed_method; - + $self->update_package_cache_flag; + 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 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); + return $meta->get_method($method_name) + if $meta->has_method($method_name); + } + return; } 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}++; + 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()) { + foreach my $method_name ($meta->get_method_list()) { next if exists $seen_method{$method_name}; $seen_method{$method_name}++; push @methods => { - name => $method_name, + name => $method_name, class => $class, code => $meta->get_method($method_name) }; @@ -245,32 +780,37 @@ sub compute_all_applicable_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 -sub attribute_metaclass { 'Class::MOP::Attribute' } - sub add_attribute { my $self = shift; # either we have an attribute object already @@ -278,119 +818,196 @@ 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(); - $self->{'%:attrs'}->{$attribute->name} = $attribute; + + # 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 + $self->remove_attribute($attribute->name) + if $self->has_attribute($attribute->name); + + # then onto installing the new accessors + $attribute->install_accessors(); + $self->get_attribute_map->{$attribute->name} = $attribute; } sub has_attribute { my ($self, $attribute_name) = @_; (defined $attribute_name && $attribute_name) || confess "You must define an attribute name"; - exists $self->{'%:attrs'}->{$attribute_name} ? 1 : 0; -} + exists $self->get_attribute_map->{$attribute_name} ? 1 : 0; +} sub get_attribute { my ($self, $attribute_name) = @_; (defined $attribute_name && $attribute_name) || confess "You must define an attribute name"; - return $self->{'%:attrs'}->{$attribute_name} - 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 = $self->{'%:attrs'}->{$attribute_name}; - delete $self->{'%:attrs'}->{$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}; + $removed_attribute->remove_accessors(); + $removed_attribute->detach_from_class(); return $removed_attribute; -} +} sub get_attribute_list { my $self = shift; - keys %{$self->{'%:attrs'}}; -} + keys %{$self->get_attribute_map}; +} sub compute_all_applicable_attributes { 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, %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()) { + foreach my $attr_name ($meta->get_attribute_list()) { next if exists $seen_attr{$attr_name}; $seen_attr{$attr_name}++; - push @attrs => { - name => $attr_name, - class => $class, - attribute => $meta->get_attribute($attr_name) - }; + push @attrs => $meta->get_attribute($attr_name); } } - return @attrs; + return @attrs; } -# Class attributes +sub find_attribute_by_name { + my ($self, $attr_name) = @_; + foreach my $class ($self->linearized_isa) { + # fetch the meta-class ... + my $meta = $self->initialize($class); + return $meta->get_attribute($attr_name) + if $meta->has_attribute($attr_name); + } + return; +} -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; +## 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 + +{ + + my %IMMUTABLE_TRANSFORMERS; + my %IMMUTABLE_OPTIONS; + + sub get_immutable_options { + my $self = shift; + return if $self->is_mutable; + confess "unable to find immutabilizing options" + unless exists $IMMUTABLE_OPTIONS{$self->name}; + my %options = %{$IMMUTABLE_OPTIONS{$self->name}}; + delete $options{IMMUTABLE_TRANSFORMER}; + return \%options; + } + + sub get_immutable_transformer { + my $self = shift; + if( $self->is_mutable ){ + my $class = blessed $self || $self; + return $IMMUTABLE_TRANSFORMERS{$class} ||= $self->create_immutable_transformer; + } + confess "unable to find transformer for immutable class" + unless exists $IMMUTABLE_OPTIONS{$self->name}; + return $IMMUTABLE_OPTIONS{$self->name}->{IMMUTABLE_TRANSFORMER}; + } + + sub make_immutable { + my $self = shift; + my %options = @_; + + my $transformer = $self->get_immutable_transformer; + $transformer->make_metaclass_immutable($self, \%options); + $IMMUTABLE_OPTIONS{$self->name} = + { %options, IMMUTABLE_TRANSFORMER => $transformer }; + + if( exists $options{debug} && $options{debug} ){ + print STDERR "# of Metaclass options: ", keys %IMMUTABLE_OPTIONS; + print STDERR "# of Immutable transformers: ", keys %IMMUTABLE_TRANSFORMERS; + } + + 1; + } + + 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; } - 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 create_immutable_transformer { + 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 $class; } 1; @@ -399,49 +1016,48 @@ __END__ =pod -=head1 NAME +=head1 NAME Class::MOP::Class - Class Meta Object =head1 SYNOPSIS + # assuming that class Foo + # has been defined, you can + # use this for introspection ... - - package Foo; - sub meta { Class::MOP::Class->initialize(__PACKAGE__) } - - # elsewhere in the code ... - + # add a method to Foo ... Foo->meta->add_method('bar' => sub { ... }) - - # get a list of all the classes searched - # the method dispatcher in the correct order + + # get a list of all the classes searched + # the method dispatcher in the correct order Foo->meta->class_precedence_list() - + # remove a method from Foo Foo->meta->remove_method('bar'); - + # or use this to actually create classes ... - - Class::MOP::Class->create('Bar' => '0.01' => ( + + Class::MOP::Class->create('Bar' => ( + version => '0.01', superclasses => [ 'Foo' ], attributes => [ Class::MOP:::Attribute->new('$bar'), - Class::MOP:::Attribute->new('$baz'), + Class::MOP:::Attribute->new('$baz'), ], methods => { calculate_bar => sub { ... }, - construct_baz => 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 +This is the largest and currently most complex part of the Perl 5 +meta-object protocol. It controls the introspection and +manipulation of Perl 5 classes (and it can create them too). The +best way to understand what this module can do, is to read the documentation for each of it's methods. =head1 METHODS @@ -452,89 +1068,198 @@ documentation for each of it's methods. =item B -This will return a B instance which is related -to this class. Thereby allowing B to actually +This will return a B instance which is related +to this class. Thereby allowing B to actually introspect itself. -As with B, B will actually -bootstrap this module by installing a number of attribute meta-objects -into it's metaclass. This will allow this class to reap all the benifits -of the MOP when subclassing it. +As with B, B will actually +bootstrap this module by installing a number of attribute meta-objects +into it's metaclass. This will allow this class to reap all the benifits +of the MOP when subclassing it. =back =head2 Class construction -These methods will handle creating B objects, -which can be used to both create new classes, and analyze -pre-existing classes. +These methods will handle creating B objects, +which can be used to both create new classes, and analyze +pre-existing classes. -This module will internally store references to all the instances -you create with these methods, so that they do not need to be +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. =over 4 -=item B ?@superclasses, - methods =E ?%methods, +=item B ?$version, + authority =E ?$authority, + superclasses =E ?@superclasses, + methods =E ?%methods, attributes =E ?%attributes)> -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. +This returns a B object, bringing the specified +C<$package_name> into existence and adding any of the C<$version>, +C<$authority>, C<@superclasses>, C<%methods> and C<%attributes> to +it. + +=item B ?@superclasses, + methods =E ?%methods, + attributes =E ?%attributes)> + +This will create an anonymous class, it works much like C but +it does not need a C<$package_name>. Instead it will create a suitably +unique package name for you to stash things into. + +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. -=item B +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. -This initializes and returns returns a B object +=item B + +This initializes and returns returns a B object for a given a C<$package_name>. -=item B +=item B + +This removes the old metaclass, and creates a new one in it's place. +Do B use this unless you really know what you are doing, it could +very easily make a very large mess of your program. + +=item B -This will construct an instance of B, it is -here so that we can actually "tie the knot" for B -to use C once all the bootstrapping is done. This +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. -=back +=item B + +This method is called as the very last thing in the +C method. This will check that the +metaclass you are creating is compatible with the metaclasses of all +your ancestors. For more inforamtion about metaclass compatibility +see the C section in L. -=head2 Object instance construction +=item B -This method is used to construct an instace structure suitable for -C-ing into your package of choice. It works in conjunction -with the Attribute protocol to collect all applicable attributes. +This will 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. -This method is B, it is up to you whether you want -to use it or not. +=item B + +Clears the package cache flag to announce to the internals that we need +to rebuild the method map. + +=back + +=head2 Object instance construction and cloning + +These methods are B, it is up to you whether you want +to use them or not. =over 4 +=item B + +Returns the class name of the instance metaclass, see L +for more information on the instance metaclasses. + +=item B + +Returns an instance of L to be used in the construction +of a new instance of the class. + +=item B + +This is a convience method for creating a new object of the class, and +blessing it into the appropriate package as well. Ideally your class +would call a C this method like so: + + sub MyClass::new { + my ($class, %param) = @_; + $class->meta->new_object(%params); + } + =item B -This will construct and instance using a HASH ref as storage -(currently only HASH references are supported). This will collect all -the applicable attributes and layout out the fields in the HASH ref, -it will then initialize them using either use the corresponding key -in C<%params> or any default value or initializer found in the +This method is used to construct an instance structure suitable for +C-ing into your package of choice. It works in conjunction +with the Attribute protocol to collect all applicable attributes. + +This will construct and instance using a HASH ref as storage +(currently only HASH references are supported). This will collect all +the applicable attributes and layout out the fields in the HASH ref, +it will then initialize them using either use the corresponding key +in C<%params> or any default value or initializer found in the attribute meta-object. +=item B + +This is a convience method for cloning an object instance, then +blessing it into the appropriate package. This method will call +C, which performs a shallow copy of the object, +see that methods documentation for more details. Ideally your +class would call a C this method like so: + + sub MyClass::clone { + my ($self, %param) = @_; + $self->meta->clone_object($self, %params); + } + +=item B + +This method is a compliment of C (which means if +you override C, you need to override this one too), +and clones the instance shallowly. + +The cloned structure returned is (like with C) an +unCed HASH reference, it is your responsibility to then bless +this cloned structure into the right class (which C will +do for you). + +As of 0.11, this method will clone the C<$instance> structure shallowly, +as opposed to the deep cloning implemented in prior versions. After much +thought, research and discussion, I have decided that anything but basic +shallow cloning is outside the scope of the meta-object protocol. I +think Yuval "nothingmuch" Kogman put it best when he said that cloning +is too I to be part of the MOP. + +=item B + +This will change the class of C<$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. + =back -=head2 Informational +=head2 Informational + +These are a few predicate methods for asking information about the class. =over 4 -=item B +=item B + +This returns true if the class is a C created anon class. -This is a read-only attribute which returns the package name for the -given B instance. +=item B -=item B +This returns true if the class is still mutable. -This is a read-only attribute which returns the C<$VERSION> of the -package for the given B instance. +=item B + +This returns true if the class has been made immutable. =back @@ -544,22 +1269,24 @@ package for the given B instance. =item B -This is a read-write attribute which represents the superclass +This is a read-write attribute which represents the superclass relationships of the class the B instance is associated with. Basically, it can get and set the C<@ISA> for you. -B -Perl will occasionally perform some C<@ISA> and method caching, if -you decide to change your superclass relationship at runtime (which -is quite insane and very much not recommened), then you should be -aware of this and the fact that this module does not make any -attempt to address this issue. - =item B -This computes the a list of all the class's ancestors in the same order -in which method dispatch will be done. This is similair to -what B does, but we don't remove duplicate names. +This computes the a list of all the class's ancestors in the same order +in which method dispatch will be done. This is similair to what +B does, but we don't remove duplicate names. + +=item B + +This returns a list based on C but with all +duplicates removed. + +=item B + +This returns a list of subclasses for this class. =back @@ -567,198 +1294,344 @@ what B does, but we don't remove duplicate names. =over 4 +=item B + +Returns a HASH ref of name to CODE reference mapping for this class. + =item B +Returns the class name of the method metaclass, see L +for more information on the method metaclasses. + =item B -This will take a C<$method_name> and CODE reference to that -C<$method> and install it into the class's package. +This will take a C<$method_name> and CODE reference to that +C<$method> and install it into the class's package. -B: -This does absolutely nothing special to C<$method> -other than use B to make sure it is tagged with the -correct name, and therefore show up correctly in stack traces and +B: +This does absolutely nothing special to C<$method> +other than use B to make sure it is tagged with the +correct name, and therefore show up correctly in stack traces and such. +=item B + +This will take a C<$method_name> and CODE reference to that +C<$method> and alias the method into the class's package. + +B: +Unlike C, this will B try to name the +C<$method> using B, it only aliases the method in +the class's package. + =item B -This just provides a simple way to check if the class implements -a specific C<$method_name>. It will I however, attempt to check +This just provides a simple way to check if the class implements +a specific C<$method_name>. It will I however, attempt to check if the class inherits the method (use C for that). -This will correctly handle functions defined outside of the package +This will correctly handle functions defined outside of the package that use a fully qualified name (C). -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 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 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 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. -In short, this method cannot always be trusted to determine if the -C<$method_name> is actually a method. However, it will DWIM about +In short, this method cannot always be trusted to determine if the +C<$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 -This will return a CODE reference of the specified C<$method_name>, +This will return a Class::MOP::Method instance related to the specified +C<$method_name>, or return undef if that method does not exist. + +The Class::MOP::Method is codifiable, so you can use it like a normal +CODE reference, see L for more information. + +=item B + +This will return a CODE reference of the specified C<$method_name>, or return undef if that method does not exist. +Unlike C this will also look in the superclasses. + =item B -This will attempt to remove a given C<$method_name> from the class. -It will return the CODE reference that it has removed, and will +This will attempt to remove a given C<$method_name> from the class. +It will return the CODE reference that it has removed, and will attempt to use B to clear the methods associated name. =item B -This will return a list of method names for all I defined -methods. It does B provide a list of all applicable methods, -including any inherited ones. If you want a list of all applicable +This will return a list of method names for all I defined +methods. It does B provide a list of all applicable methods, +including any inherited ones. If you want a list of all applicable methods, use the C method. =item B -This will return a list of all the methods names this class will -respond to, taking into account inheritance. The list will be a list of -HASH references, each one containing the following information; method -name, the name of the class in which the method lives and a CODE +This will return a list of all the methods names this class will +respond to, taking into account inheritance. The list will be a list of +HASH references, each one containing the following information; method +name, the name of the class in which the method lives and a CODE reference for the actual method. =item B -This will traverse the inheritence hierarchy and locate all methods -with a given C<$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<$method_name>), the name of the class in which the method +This will traverse the inheritence hierarchy and locate all methods +with a given C<$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<$method_name>), the name of the class in which the method lives and a CODE reference for the actual method. -The list of methods produced is a distinct list, meaning there are no -duplicates in it. This is especially useful for things like object -initialization and destruction where you only want the method called +The list of methods produced is a distinct list, meaning there are no +duplicates in it. This is especially useful for things like object +initialization and destruction where you only want the method called once, and in the correct order. +=item B + +This will return the first method to match a given C<$method_name> in +the superclasses, this is basically equivalent to calling +C, but it can be dispatched at runtime. + +=back + +=head2 Method Modifiers + +Method modifiers are a concept borrowed from CLOS, in which a method +can be wrapped with I, I and I method modifiers +that will be called everytime the method is called. + +=head3 How method modifiers work? + +Method modifiers work by wrapping the original method and then replacing +it in the classes symbol table. The wrappers will handle calling all the +modifiers in the appropariate orders and preserving the calling context +for the original method. + +Each method modifier serves a particular purpose, which may not be +obvious to users of other method wrapping modules. To start with, the +return values of I and I modifiers are ignored. This is +because thier purpose is B to filter the input and output of the +primary method (this is done with an I modifier). This may seem +like an odd restriction to some, but doing this allows for simple code +to be added at the begining or end of a method call without jeapordizing +the normal functioning of the primary method or placing any extra +responsibility on the code of the modifier. Of course if you have more +complex needs, then use the I modifier, which uses a variation +of continutation passing style to allow for a high degree of flexibility. + +Before and around modifiers are called in last-defined-first-called order, +while after modifiers are called in first-defined-first-called order. So +the call tree might looks something like this: + + before 2 + before 1 + around 2 + around 1 + primary + after 1 + after 2 + +To see examples of using method modifiers, see the following examples +included in the distribution; F, F, +F and F. There is also a +classic CLOS usage example in the test F<017_add_method_modifier.t>. + +=head3 What is the performance impact? + +Of course there is a performance cost associated with method modifiers, +but we have made every effort to make that cost be directly proportional +to the amount of modifier features you utilize. + +The wrapping method does it's best to B do as much work as it +absolutely needs to. In order to do this we have moved some of the +performance costs to set-up time, where they are easier to amortize. + +All this said, my benchmarks have indicated the following: + + simple wrapper with no modifiers 100% slower + simple wrapper with simple before modifier 400% slower + simple wrapper with simple after modifier 450% slower + simple wrapper with simple around modifier 500-550% slower + simple wrapper with all 3 modifiers 1100% slower + +These numbers may seem daunting, but you must remember, every feature +comes with some cost. To put things in perspective, just doing a simple +C which does nothing but extract the name of the method called +and return it costs about 400% over a normal method call. + +=over 4 + +=item B + +This will wrap the method at C<$method_name> and the supplied C<$code> +will be passed the C<@_> arguments, and called before the original +method is called. As specified above, the return value of the I +method modifiers is ignored, and it's ability to modify C<@_> is +fairly limited. If you need to do either of these things, use an +C method modifier. + +=item B + +This will wrap the method at C<$method_name> so that the original +method will be called, it's return values stashed, and then the +supplied C<$code> will be passed the C<@_> arguments, and called. +As specified above, the return value of the I method +modifiers is ignored, and it cannot modify the return values of +the original method. If you need to do either of these things, use an +C method modifier. + +=item B + +This will wrap the method at C<$method_name> so that C<$code> +will be called and passed the original method as an extra argument +at the begining of the C<@_> argument list. This is a variation of +continuation passing style, where the function prepended to C<@_> +can be considered a continuation. It is up to C<$code> if it calls +the original method or not, there is no restriction on what the +C<$code> can or cannot do. + =back =head2 Attributes -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 +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. =over 4 =item B -=item B +Returns the class name of the attribute metaclass, see L +for more information on the attribute metaclasses. + +=item B + +This returns a HASH ref of name to attribute meta-object mapping. -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 +=item B + +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. -It should be noted that any accessor, reader/writer or predicate -methods which the C<$attribute_meta_object> has will be installed +It should be noted that any accessor, reader/writer or predicate +methods which the C<$attribute_meta_object> has will be installed into the class at this time. +B +If an attribute already exists for C<$attribute_name>, the old one +will be removed (as well as removing all it's accessors), and then +the new one added. + =item B -Checks to see if this class has an attribute by the name of +Checks to see if this class has an attribute by the name of C<$attribute_name> and returns a boolean. =item B -Returns the attribute meta-object associated with C<$attribute_name>, -if none is found, it will return undef. +Returns the attribute meta-object associated with C<$attribute_name>, +if none is found, it will return undef. =item B -This will remove the attribute meta-object stored at -C<$attribute_name>, then return the removed attribute meta-object. +This will remove the attribute meta-object stored at +C<$attribute_name>, then return the removed attribute meta-object. -B -Removing an attribute will only affect future instances of -the class, it will not make any attempt to remove the attribute from +B +Removing an attribute will only affect future instances of +the class, it will not make any attempt to remove the attribute from any existing instances of the class. -It should be noted that any accessor, reader/writer or predicate -methods which the attribute meta-object stored at C<$attribute_name> -has will be removed from the class at this time. This B make -these attributes somewhat inaccessable in previously created -instances. But if you are crazy enough to do this at runtime, then +It should be noted that any accessor, reader/writer or predicate +methods which the attribute meta-object stored at C<$attribute_name> +has will be removed from the class at this time. This B make +these attributes somewhat inaccessable in previously created +instances. But if you are crazy enough to do this at runtime, then you are crazy enough to deal with something like this :). =item B -This returns a list of attribute names which are defined in the local -class. If you want a list of all applicable attributes for a class, +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. =item B -This will traverse the inheritance heirachy and return a list of HASH -references for all the applicable attributes for this class. The HASH -references will contain the following information; the attribute name, -the class which the attribute is associated with and the actual -attribute meta-object. +This will traverse the inheritance heirachy and return a list of all +the applicable attributes for this class. It does not construct a +HASH reference like C because all +that same information is discoverable through the attribute +meta-object itself. -=back +=item B -=head2 Package Variables +This method will traverse the inheritance heirachy and find the +first attribute whose name matches C<$attr_name>, then return it. +It will return undef if nothing is found. -Since Perl's classes are built atop the Perl package system, it is -fairly common to use package scoped variables for things like static -class variables. The following methods are convience methods for -the creation and inspection of package scoped variables. +=back + +=head2 Class Immutability =over 4 -=item B +=item B + +This method will invoke a tranforamtion upon the class which will +make it immutable. Details of this transformation can be found in +the L documentation. + +=item B -Given a C<$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. +This method will reverse tranforamtion upon the class which +made it immutable. -=item B +=item B -This will return a reference to the package variable in -C<$variable_name>. +Return a transformer suitable for making this class immutable or, if this +class is immutable, the transformer used to make it immutable. -=item B +=item B -Returns true (C<1>) if there is a package variable defined for -C<$variable_name>, and false (C<0>) otherwise. +If the class is immutable, return the options used to make it immutable. -=item B +=item B -This will attempt to remove the package variable at C<$variable_name>. +Create a transformer suitable for making this class immutable =back -=head1 AUTHOR +=head1 AUTHORS Stevan Little Estevan@iinteractive.comE =head1 COPYRIGHT AND LICENSE -Copyright 2006 by Infinity Interactive, Inc. +Copyright 2006-2008 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