X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FClass%2FMOP%2FClass.pm;h=6902284f53ca9421eaef469399a75435886b7934;hb=864826055ffa48aba41ba1a016c09f24b51e85c4;hp=1634c8c20b7d5334f2136f5c69093f55168e050f;hpb=7b31baf476f970830c62cafa82d8f2efcd4ac1b6;p=gitmo%2FClass-MOP.git diff --git a/lib/Class/MOP/Class.pm b/lib/Class/MOP/Class.pm index 1634c8c..6902284 100644 --- a/lib/Class/MOP/Class.pm +++ b/lib/Class/MOP/Class.pm @@ -5,75 +5,232 @@ use strict; use warnings; use Carp 'confess'; -use Scalar::Util 'blessed', 'reftype'; +use Scalar::Util 'blessed', 'reftype', 'weaken'; use Sub::Name 'subname'; use B 'svref_2object'; -our $VERSION = '0.03'; +our $VERSION = '0.20'; +our $AUTHORITY = 'cpan:STEVAN'; -# Self-introspection +use base 'Class::MOP::Module'; -sub meta { Class::MOP::Class->initialize($_[0]) } +use Class::MOP::Instance; + +# Self-introspection + +sub meta { Class::MOP::Class->initialize(blessed($_[0]) || $_[0]) } # Creation + +sub initialize { + my $class = shift; + my $package_name = shift; + (defined $package_name && $package_name && !blessed($package_name)) + || confess "You must pass a package name and it cannot be blessed"; + $class->construct_class_instance(':package' => $package_name, @_); +} -{ - # Metaclasses are singletons, so we cache them here. - # there is no need to worry about destruction though - # because they should die only when the program dies. - # After all, do package definitions even get reaped? - my %METAS; - sub initialize { - my $class = shift; - my $package_name = shift; - (defined $package_name && $package_name) - || confess "You must pass a package name"; - # make sure the package name is not blessed - $package_name = blessed($package_name) || $package_name; - return $METAS{$package_name} if exists $METAS{$package_name}; - $METAS{$package_name} = $class->construct_class_instance($package_name, @_); - } +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 $package_name = shift; - (defined $package_name && $package_name) - || confess "You must pass a package name"; - $class = blessed($class) || $class; - if ($class =~ /^Class::MOP::/) { - bless { - '$:package' => $package_name, - '%:attributes' => {}, - '$:attribute_metaclass' => 'Class::MOP::Attribute', - '$:method_metaclass' => 'Class::MOP::Method', - } => $class; - } - else { +# NOTE: (meta-circularity) +# this is a special form of &construct_instance +# (see below), which is used to construct class +# meta-object instances for any Class::MOP::* +# class. All other classes will use the more +# normal &construct_instance. +sub construct_class_instance { + my $class = shift; + my %options = @_; + my $package_name = $options{':package'}; + (defined $package_name && $package_name) + || confess "You must pass a package name"; + # NOTE: + # return the metaclass if we have it cached, + # and it is still defined (it has not been + # reaped by DESTROY yet, which can happen + # annoyingly enough during global destruction) + return Class::MOP::get_metaclass_by_name($package_name) + if Class::MOP::does_metaclass_exist($package_name); + + # NOTE: + # we need to deal with the possibility + # of class immutability here, and then + # get the name of the class appropriately + $class = (blessed($class) + ? ($class->is_immutable + ? $class->get_mutable_metaclass_name() + : blessed($class)) + : $class); + + $class = blessed($class) || $class; + # now create the metaclass + my $meta; + if ($class =~ /^Class::MOP::Class$/) { + no strict 'refs'; + $meta = bless { + # inherited from Class::MOP::Package + '$:package' => $package_name, + # NOTE: - # it is safe to use meta here because - # class will always be a subclass of - # Class::MOP::Class, which defines meta - bless $class->meta->construct_instance(':package' => $package_name, @_) => $class + # since the following attributes will + # actually be loaded from the symbol + # table, and actually bypass the instance + # entirely, we can just leave these things + # listed here for reference, because they + # should not actually have a value associated + # with the slot. + '%:namespace' => \undef, + # inherited from Class::MOP::Module + '$:version' => \undef, + '$:authority' => \undef, + # defined in Class::MOP::Class + + '%:methods' => {}, + '%:attributes' => {}, + '$:attribute_metaclass' => $options{':attribute_metaclass'} || 'Class::MOP::Attribute', + '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method', + '$:instance_metaclass' => $options{':instance_metaclass'} || 'Class::MOP::Instance', + } => $class; + } + else { + # NOTE: + # it is safe to use meta here because + # class will always be a subclass of + # Class::MOP::Class, which defines meta + $meta = $class->meta->construct_instance(%options) + } + + # and check the metaclass compatibility + $meta->check_metaclass_compatability(); + + Class::MOP::store_metaclass_by_name($package_name, $meta); + + # NOTE: + # we need to weaken any anon classes + # so that they can call DESTROY properly + Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class; + + $meta; +} + +sub check_metaclass_compatability { + my $self = shift; + + # this is always okay ... + return if blessed($self) eq 'Class::MOP::Class' && + $self->instance_metaclass eq 'Class::MOP::Instance'; + + my @class_list = $self->class_precedence_list; + shift @class_list; # shift off $self->name + + foreach my $class_name (@class_list) { + my $meta = Class::MOP::get_metaclass_by_name($class_name) || next; + + # NOTE: + # we need to deal with the possibility + # of class immutability here, and then + # get the name of the class appropriately + my $meta_type = ($meta->is_immutable + ? $meta->get_mutable_metaclass_name() + : blessed($meta)); + + ($self->isa($meta_type)) + || confess $self->name . "->meta => (" . (blessed($self)) . ")" . + " is not compatible with the " . + $class_name . "->meta => (" . ($meta_type) . ")"; + # NOTE: + # we also need to check that instance metaclasses + # are compatabile in the same the class. + ($self->instance_metaclass->isa($meta->instance_metaclass)) + || confess $self->name . "->meta => (" . ($self->instance_metaclass) . ")" . + " is not compatible with the " . + $class_name . "->meta => (" . ($meta->instance_metaclass) . ")"; + } +} + +## ANON classes + +{ + # NOTE: + # this should be sufficient, if you have a + # use case where it is not, write a test and + # I will change it. + my $ANON_CLASS_SERIAL = 0; + + # NOTE: + # we need a sufficiently annoying prefix + # this should suffice for now, this is + # used in a couple of places below, so + # need to put it up here for now. + my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::'; + + sub is_anon_class { + my $self = shift; + $self->name =~ /^$ANON_CLASS_PREFIX/ ? 1 : 0; + } + + sub create_anon_class { + my ($class, %options) = @_; + my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL; + return $class->create($package_name, %options); + } + + # NOTE: + # this will only get called for + # anon-classes, all other calls + # are assumed to occur during + # global destruction and so don't + # really need to be handled explicitly + sub DESTROY { + my $self = shift; + return unless $self->name =~ /^$ANON_CLASS_PREFIX/; + my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/); + no strict 'refs'; + foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) { + delete ${$ANON_CLASS_PREFIX . $serial_id}{$key}; } + delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'}; } + } +# creating classes with MOP ... + sub create { - my ($class, $package_name, $package_version, %options) = @_; + 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) = @_; + 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 $@; + 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: @@ -100,80 +257,109 @@ sub create { # all these attribute readers will be bootstrapped # away in the Class::MOP bootstrap section -sub name { $_[0]->{'$:package'} } sub get_attribute_map { $_[0]->{'%:attributes'} } sub attribute_metaclass { $_[0]->{'$:attribute_metaclass'} } sub method_metaclass { $_[0]->{'$:method_metaclass'} } +sub instance_metaclass { $_[0]->{'$:instance_metaclass'} } + +# FIXME: +# this is a prime canidate for conversion to XS +sub get_method_map { + my $self = shift; + my $map = $self->{'%:methods'}; + + my $class_name = $self->name; + my $method_metaclass = $self->method_metaclass; + + foreach my $symbol ($self->list_all_package_symbols('CODE')) { + my $code = $self->get_package_symbol('&' . $symbol); + + next if exists $map->{$symbol} && $map->{$symbol}->body == $code; + + my $gv = svref_2object($code)->GV; + next if ($gv->STASH->NAME || '') ne $class_name && + ($gv->NAME || '') ne '__ANON__'; + + $map->{$symbol} = $method_metaclass->wrap($code); + } + + return $map; +} # Instance Construction & Cloning sub new_object { my $class = shift; - bless $class->construct_instance(@_) => $class->name; + # NOTE: + # we need to protect the integrity of the + # Class::MOP::Class singletons here, so we + # delegate this to &construct_class_instance + # which will deal with the singletons + return $class->construct_class_instance(@_) + if $class->name->isa('Class::MOP::Class'); + return $class->construct_instance(@_); } sub construct_instance { my ($class, %params) = @_; - my $instance = {}; + my $meta_instance = $class->get_meta_instance(); + my $instance = $meta_instance->create_instance(); foreach my $attr ($class->compute_all_applicable_attributes()) { - my $init_arg = $attr->has_init_arg() ? $attr->init_arg() : $attr->name; - # try to fetch the init arg from the %params ... - my $val; - $val = $params{$init_arg} if exists $params{$init_arg}; - # if nothing was in the %params, we can use the - # attribute's default value (if it has one) - $val ||= $attr->default($instance) if $attr->has_default(); - $instance->{$attr->name} = $val; + $attr->initialize_instance_slot($meta_instance, $instance, \%params); } return $instance; } +sub get_meta_instance { + my $class = shift; + return $class->instance_metaclass->new( + $class, + $class->compute_all_applicable_attributes() + ); +} + sub clone_object { my $class = shift; my $instance = shift; - bless $class->clone_instance($instance, @_) => $class->name; + (blessed($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, $self, %params) = @_; - (blessed($self)) + my ($class, $instance, %params) = @_; + (blessed($instance)) || confess "You can only clone instances, \$self is not a blessed instance"; - # NOTE: - # this should actually do a deep clone - # instead of this cheap hack. I will - # add that in later. - # (use the Class::Cloneable::Util code) - my $clone = { %{$self} }; - foreach my $attr ($class->compute_all_applicable_attributes()) { - my $init_arg = $attr->has_init_arg() ? $attr->init_arg() : $attr->name; - # try to fetch the init arg from the %params ... - $clone->{$attr->name} = $params{$init_arg} - if exists $params{$init_arg}; + my $meta_instance = $class->get_meta_instance(); + my $clone = $meta_instance->clone_instance($instance); + foreach my $key (keys %params) { + next unless $meta_instance->is_valid_slot($key); + $meta_instance->set_slot_value($clone, $key, $params{$key}); } return $clone; } -# Informational - -# &name should be here too, but it is above -# because it gets bootstrapped away - -sub version { - my $self = shift; - no strict 'refs'; - ${$self->name . '::VERSION'}; -} - # Inheritance sub superclasses { my $self = shift; - no strict 'refs'; if (@_) { my @supers = @_; - @{$self->name . '::ISA'} = @supers; + @{$self->get_package_symbol('@ISA')} = @supers; + # NOTE: + # we need to check the metaclass + # compatability here so that we can + # be sure that the superclass is + # not potentially creating an issues + # we don't know about + $self->check_metaclass_compatability(); } - @{$self->name . '::ISA'}; + @{$self->get_package_symbol('@ISA')}; } sub class_precedence_list { @@ -183,8 +369,8 @@ sub class_precedence_list { # This will do nothing if all is well, and blow # up otherwise. Yes, it's an ugly hack, better # suggestions are welcome. - { $self->name->isa('This is a test for circular inheritance') } - # ... and no back to our regularly scheduled program + { ($self->name || return)->isa('This is a test for circular inheritance') } + # ... and now back to our regularly scheduled program ( $self->name, map { @@ -199,47 +385,120 @@ sub add_method { my ($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 $full_method_name = ($self->name . '::' . $method_name); - - no strict 'refs'; - no warnings 'redefine'; - *{$full_method_name} = subname $full_method_name => $method; + + my $body; + if (blessed($method)) { + $body = $method->body; + } + else { + $body = $method; + ('CODE' eq (reftype($body) || '')) + || confess "Your code block must be a CODE reference"; + $method = $self->method_metaclass->wrap($body); + } + $self->get_method_map->{$method_name} = $method; + + my $full_method_name = ($self->name . '::' . $method_name); + $self->add_package_symbol("&${method_name}" => subname $full_method_name => $body); } { - - ## private utility functions for has_method - my $_find_subroutine_package_name = sub { eval { svref_2object($_[0])->GV->STASH->NAME } || '' }; - my $_find_subroutine_name = sub { eval { svref_2object($_[0])->GV->NAME } || '' }; - - sub has_method { + my $fetch_and_prepare_method = sub { my ($self, $method_name) = @_; + # fetch it locally + my $method = $self->get_method($method_name); + # if we dont have local ... + unless ($method) { + # try to find the next method + $method = $self->find_next_method_by_name($method_name); + # die if it does not exist + (defined $method) + || confess "The method '$method_name' is not found in the inherience hierarchy for this class"; + # and now make sure to wrap it + # even if it is already wrapped + # because we need a new sub ref + $method = Class::MOP::Method::Wrapped->wrap($method); + } + else { + # now make sure we wrap it properly + $method = Class::MOP::Method::Wrapped->wrap($method) + unless $method->isa('Class::MOP::Method::Wrapped'); + } + $self->add_method($method_name => $method); + return $method; + }; + + sub add_before_method_modifier { + my ($self, $method_name, $method_modifier) = @_; (defined $method_name && $method_name) - || confess "You must define a method name"; + || confess "You must pass in a method name"; + my $method = $fetch_and_prepare_method->($self, $method_name); + $method->add_before_modifier(subname ':before' => $method_modifier); + } + + sub add_after_method_modifier { + my ($self, $method_name, $method_modifier) = @_; + (defined $method_name && $method_name) + || confess "You must pass in a method name"; + my $method = $fetch_and_prepare_method->($self, $method_name); + $method->add_after_modifier(subname ':after' => $method_modifier); + } - my $sub_name = ($self->name . '::' . $method_name); + sub add_around_method_modifier { + my ($self, $method_name, $method_modifier) = @_; + (defined $method_name && $method_name) + || confess "You must pass in a method name"; + my $method = $fetch_and_prepare_method->($self, $method_name); + $method->add_around_modifier(subname ':around' => $method_modifier); + } + + # NOTE: + # the methods above used to be named like this: + # ${pkg}::${method}:(before|after|around) + # but this proved problematic when using one modifier + # to wrap multiple methods (something which is likely + # to happen pretty regularly IMO). So instead of naming + # it like this, I have chosen to just name them purely + # with their modifier names, like so: + # :(before|after|around) + # The fact is that in a stack trace, it will be fairly + # evident from the context what method they are attached + # to, and so don't need the fully qualified name. +} + +sub alias_method { + my ($self, $method_name, $method) = @_; + (defined $method_name && $method_name) + || confess "You must define a method name"; + + my $body = (blessed($method) ? $method->body : $method); + ('CODE' eq (reftype($body) || '')) + || confess "Your code block must be a CODE reference"; - no strict 'refs'; - return 0 if !defined(&{$sub_name}); - return 0 if $_find_subroutine_package_name->(\&{$sub_name}) ne $self->name && - $_find_subroutine_name->(\&{$sub_name}) ne '__ANON__'; - return 1; - } + $self->add_package_symbol("&${method_name}" => $body); +} +sub has_method { + my ($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 { my ($self, $method_name) = @_; (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 { @@ -249,17 +508,23 @@ sub remove_method { my $removed_method = $self->get_method($method_name); - no strict 'refs'; - delete ${$self->name . '::'}{$method_name} - if defined $removed_method; + do { + $self->remove_package_symbol("&${method_name}"); + delete $self->get_method_map->{$method_name}; + } if defined $removed_method; 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) = @_; + # FIXME + return $self->name->can($method_name); } sub compute_all_applicable_methods { @@ -310,7 +575,28 @@ sub find_all_methods_by_name { } if $meta->has_method($method_name); } return @methods; +} +sub find_next_method_by_name { + my ($self, $method_name) = @_; + (defined $method_name && $method_name) + || confess "You must define a method name to find"; + # keep a record of what we have seen + # here, this will handle all the + # inheritence issues because we are + # using the &class_precedence_list + my %seen_class; + my @cpl = $self->class_precedence_list(); + shift @cpl; # discard ourselves + foreach my $class (@cpl) { + next if $seen_class{$class}; + $seen_class{$class}++; + # fetch the meta-class ... + my $meta = $self->initialize($class); + return $meta->get_method($method_name) + if $meta->has_method($method_name); + } + return; } ## Attributes @@ -323,8 +609,21 @@ sub add_attribute { # 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)"; + + # first we attach our new attribute + # because it might need certain information + # about the class which it is attached to $attribute->attach_to_class($self); - $attribute->install_accessors(); + + # then we remove attributes of a conflicting + # name here so that we can properly detach + # the old attr object, and remove any + # accessors it would have generated + $self->remove_attribute($attribute->name) + if $self->has_attribute($attribute->name); + + # then onto installing the new accessors + $attribute->install_accessors(); $self->get_attribute_map->{$attribute->name} = $attribute; } @@ -340,7 +639,10 @@ sub get_attribute { (defined $attribute_name && $attribute_name) || confess "You must define an attribute name"; return $self->get_attribute_map->{$attribute_name} - if $self->has_attribute($attribute_name); + # NOTE: + # this will return undef anyway, so no need ... + # if $self->has_attribute($attribute_name); + #return; } sub remove_attribute { @@ -348,10 +650,10 @@ sub remove_attribute { (defined $attribute_name && $attribute_name) || confess "You must define an attribute name"; my $removed_attribute = $self->get_attribute_map->{$attribute_name}; - delete $self->get_attribute_map->{$attribute_name} - if defined $removed_attribute; - $removed_attribute->remove_accessors(); - $removed_attribute->detach_from_class(); + return unless defined $removed_attribute; + delete $self->get_attribute_map->{$attribute_name}; + $removed_attribute->remove_accessors(); + $removed_attribute->detach_from_class(); return $removed_attribute; } @@ -382,55 +684,31 @@ sub compute_all_applicable_attributes { return @attrs; } -# Class attributes - -sub add_package_variable { - my ($self, $variable, $initial_value) = @_; - (defined $variable && $variable =~ /^[\$\@\%]/) - || confess "variable name does not have a sigil"; - - my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); - if (defined $initial_value) { - no strict 'refs'; - *{$self->name . '::' . $name} = $initial_value; - } - else { - eval $sigil . $self->name . '::' . $name; - confess "Could not create package variable ($variable) because : $@" if $@; +sub find_attribute_by_name { + my ($self, $attr_name) = @_; + # keep a record of what we have seen + # here, this will handle all the + # inheritence issues because we are + # using the &class_precedence_list + my %seen_class; + foreach my $class ($self->class_precedence_list()) { + next if $seen_class{$class}; + $seen_class{$class}++; + # fetch the meta-class ... + my $meta = $self->initialize($class); + return $meta->get_attribute($attr_name) + if $meta->has_attribute($attr_name); } + return; } -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 . '::'}{$name} ? 1 : 0; -} +## Class closing -sub get_package_variable { - my ($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 . '::' . $name; -} +sub is_mutable { 1 } +sub is_immutable { 0 } -sub remove_package_variable { - my ($self, $variable) = @_; - (defined $variable && $variable =~ /^[\$\@\%]/) - || confess "variable name does not have a sigil"; - my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); - no strict 'refs'; - delete ${$self->name . '::'}{$name}; +sub make_immutable { + return Class::MOP::Class::Immutable->make_metaclass_immutable(@_); } 1; @@ -445,12 +723,10 @@ Class::MOP::Class - Class Meta Object =head1 SYNOPSIS - # use this for introspection ... - - package Foo; - sub meta { Class::MOP::Class->initialize(__PACKAGE__) } + # assuming that class Foo + # has been defined, you can - # elsewhere in the code ... + # use this for introspection ... # add a method to Foo ... Foo->meta->add_method('bar' => sub { ... }) @@ -464,7 +740,8 @@ Class::MOP::Class - Class Meta Object # or use this to actually create classes ... - Class::MOP::Class->create('Bar' => '0.01' => ( + Class::MOP::Class->create('Bar' => ( + version => '0.01', superclasses => [ 'Foo' ], attributes => [ Class::MOP:::Attribute->new('$bar'), @@ -515,22 +792,38 @@ created any more than nessecary. Basically, they are singletons. =over 4 -=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. +C<$package_name> into existence and adding any of the C<$version>, +C<$authority>, C<@superclasses>, C<%methods> and C<%attributes> to +it. + +=item B ?@superclasses, + methods =E ?%methods, + attributes =E ?%attributes)> -=item B +This will create an anonymous class, it works much like C but +it does not need a C<$package_name>. Instead it will create a suitably +unique package name for you to stash things into. + +=item B This initializes and returns returns a B object for a given a C<$package_name>. -=item B +=item B + +This removes the old metaclass, and creates a new one in it's place. +Do B use this unless you really know what you are doing, it could +very easily make a very large mess of your program. + +=item B This will construct an instance of B, it is here so that we can actually "tie the knot" for B @@ -538,6 +831,14 @@ to use C once all the bootstrapping is done. This method is used internally by C and should never be called from outside of that method really. +=item B + +This method is called as the very last thing in the +C method. This will check that the +metaclass you are creating is compatible with the metaclasses of all +your ancestors. For more inforamtion about metaclass compatibility +see the C section in L. + =back =head2 Object instance construction and cloning @@ -547,6 +848,10 @@ to use them or not. =over 4 +=item B + +=item B + =item B This is a convience method for creating a new object of the class, and @@ -577,8 +882,10 @@ attribute meta-object. =item B This is a convience method for cloning an object instance, then -blessing it into the appropriate package. Ideally your class -would call a C this method like so: +blessing it into the appropriate package. This method will call +C, which performs a shallow copy of the object, +see that methods documentation for more details. Ideally your +class would call a C this method like so: sub MyClass::clone { my ($self, %param) = @_; @@ -591,30 +898,34 @@ but that is considered bad style, so we do not do that. =item B This method is a compliment of C (which means if -you override C, you need to override this one too). +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). -This method will clone the C<$instance> structure created by the -C method, and apply any C<%params> passed to it -to change the attribute values. The structure returned is (like with -C) an unCed HASH reference, it is your -responsibility to then bless this cloned structure into the right -class. +As of 0.11, this method will clone the C<$instance> structure shallowly, +as opposed to the deep cloning implemented in prior versions. After much +thought, research and discussion, I have decided that anything but basic +shallow cloning is outside the scope of the meta-object protocol. I +think Yuval "nothingmuch" Kogman put it best when he said that cloning +is too I to be part of the MOP. =back =head2 Informational -=over 4 +These are a few predicate methods for asking information about the class. -=item B +=over 4 -This is a read-only attribute which returns the package name for the -given B instance. +=item B -=item B +=item B -This is a read-only attribute which returns the C<$VERSION> of the -package for the given B instance. +=item B =back @@ -647,6 +958,8 @@ what B does, but we don't remove duplicate names. =over 4 +=item B + =item B =item B @@ -660,6 +973,16 @@ other than use B to make sure it is tagged with the correct name, and therefore show up correctly in stack traces and such. +=item B + +This will take a C<$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 @@ -686,9 +1009,19 @@ C<$method_name> is actually a method. However, it will DWIM about =item B -This will return a CODE reference of the specified C<$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<$method_name> from the class. @@ -724,6 +1057,110 @@ duplicates in it. This is especially useful for things like object initialization and destruction where you only want the method called once, and in the correct order. +=item B + +This will return the first method to match a given C<$method_name> in +the superclasses, this is basically equivalent to calling +C, but it can be dispatched at runtime. + +=back + +=head2 Method Modifiers + +Method modifiers are a concept borrowed from CLOS, in which a method +can be wrapped with I, I and I method modifiers +that will be called everytime the method is called. + +=head3 How method modifiers work? + +Method modifiers work by wrapping the original method and then replacing +it in the classes symbol table. The wrappers will handle calling all the +modifiers in the appropariate orders and preserving the calling context +for the original method. + +Each method modifier serves a particular purpose, which may not be +obvious to users of other method wrapping modules. To start with, the +return values of I and I modifiers are ignored. This is +because thier purpose is B to filter the input and output of the +primary method (this is done with an I modifier). This may seem +like an odd restriction to some, but doing this allows for simple code +to be added at the begining or end of a method call without jeapordizing +the normal functioning of the primary method or placing any extra +responsibility on the code of the modifier. Of course if you have more +complex needs, then use the I modifier, which uses a variation +of continutation passing style to allow for a high degree of flexibility. + +Before and around modifiers are called in last-defined-first-called order, +while after modifiers are called in first-defined-first-called order. So +the call tree might looks something like this: + + before 2 + before 1 + around 2 + around 1 + primary + after 1 + after 2 + +To see examples of using method modifiers, see the following examples +included in the distribution; F, F, +F and F. There is also a +classic CLOS usage example in the test F<017_add_method_modifier.t>. + +=head3 What is the performance impact? + +Of course there is a performance cost associated with method modifiers, +but we have made every effort to make that cost be directly proportional +to the amount of modifier features you utilize. + +The wrapping method does it's best to B do as much work as it +absolutely needs to. In order to do this we have moved some of the +performance costs to set-up time, where they are easier to amortize. + +All this said, my benchmarks have indicated the following: + + simple wrapper with no modifiers 100% slower + simple wrapper with simple before modifier 400% slower + simple wrapper with simple after modifier 450% slower + simple wrapper with simple around modifier 500-550% slower + simple wrapper with all 3 modifiers 1100% slower + +These numbers may seem daunting, but you must remember, every feature +comes with some cost. To put things in perspective, just doing a simple +C which does nothing but extract the name of the method called +and return it costs about 400% over a normal method call. + +=over 4 + +=item B + +This will wrap the method at C<$method_name> and the supplied C<$code> +will be passed the C<@_> arguments, and called before the original +method is called. As specified above, the return value of the I +method modifiers is ignored, and it's ability to modify C<@_> is +fairly limited. If you need to do either of these things, use an +C method modifier. + +=item B + +This will wrap the method at C<$method_name> so that the original +method will be called, it's return values stashed, and then the +supplied C<$code> will be passed the C<@_> arguments, and called. +As specified above, the return value of the I method +modifiers is ignored, and it cannot modify the return values of +the original method. If you need to do either of these things, use an +C method modifier. + +=item B + +This will wrap the method at C<$method_name> so that C<$code> +will be called and passed the original method as an extra argument +at the begining of the C<@_> argument list. This is a variation of +continuation passing style, where the function prepended to C<@_> +can be considered a continuation. It is up to C<$code> if it calls +the original method or not, there is no restriction on what the +C<$code> can or cannot do. + =back =head2 Attributes @@ -754,6 +1191,11 @@ 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 @@ -795,45 +1237,28 @@ HASH reference like C because all that same information is discoverable through the attribute meta-object itself. -=back - -=head2 Package Variables - -Since Perl's classes are built atop the Perl package system, it is -fairly common to use package scoped variables for things like static -class variables. The following methods are convience methods for -the creation and inspection of package scoped variables. - -=over 4 - -=item B +=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<$variable_name> -implies. +This method will traverse the inheritance heirachy and find the +first attribute whose name matches C<$attr_name>, then return it. +It will return undef if nothing is found. -=item B - -This will return a reference to the package variable in -C<$variable_name>. - -=item B +=back -Returns true (C<1>) if there is a package variable defined for -C<$variable_name>, and false (C<0>) otherwise. +=head2 Class closing -=item B +=over 4 -This will attempt to remove the package variable at C<$variable_name>. +=item B =back -=head1 AUTHOR +=head1 AUTHORS Stevan Little Estevan@iinteractive.comE +Yuval Kogman Enothingmuch@woobling.comE + =head1 COPYRIGHT AND LICENSE Copyright 2006 by Infinity Interactive, Inc. @@ -843,4 +1268,4 @@ L This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. -=cut \ No newline at end of file +=cut