X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FClass%2FMOP%2FClass.pm;h=abfec6424048671cbc0a98c4833cd0dff89fb227;hb=f1dc35403251ed96f803ff9977f41a53b64eb1cd;hp=9a80985133af990e21adffb49719c5456c641e91;hpb=27bbcf6c7d1c23e2e071f921d279d12bdd2fcaa4;p=gitmo%2FClass-MOP.git diff --git a/lib/Class/MOP/Class.pm b/lib/Class/MOP/Class.pm index 9a80985..abfec64 100644 --- a/lib/Class/MOP/Class.pm +++ b/lib/Class/MOP/Class.pm @@ -11,7 +11,7 @@ use Class::MOP::Method::Wrapped; use Carp 'confess'; use Scalar::Util 'blessed', 'weaken'; -our $VERSION = '0.76'; +our $VERSION = '0.78'; $VERSION = eval $VERSION; our $AUTHORITY = 'cpan:STEVAN'; @@ -73,8 +73,7 @@ sub construct_class_instance { # now create the metaclass my $meta; if ($class eq 'Class::MOP::Class') { - no strict 'refs'; - $meta = $class->_new($options) + $meta = $class->_new($options); } else { # NOTE: @@ -157,37 +156,32 @@ sub check_metaclass_compatibility { my @class_list = $self->linearized_isa; shift @class_list; # shift off $self->name - foreach my $class_name (@class_list) { - my $meta = Class::MOP::get_metaclass_by_name($class_name) || next; + foreach my $superclass_name (@class_list) { + my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next; # NOTE: # we need to deal with the possibility # of class immutability here, and then # get the name of the class appropriately - my $meta_type = ($meta->is_immutable - ? $meta->get_mutable_metaclass_name() - : ref($meta)); + my $super_meta_type + = $super_meta->is_immutable + ? $super_meta->get_mutable_metaclass_name() + : ref($super_meta); - ($self->isa($meta_type)) + ($self->isa($super_meta_type)) || confess $self->name . "->meta => (" . (ref($self)) . ")" . " is not compatible with the " . - $class_name . "->meta => (" . ($meta_type) . ")"; + $superclass_name . "->meta => (" . ($super_meta_type) . ")"; # NOTE: # we also need to check that instance metaclasses # are compatibile in the same the class. - ($self->instance_metaclass->isa($meta->instance_metaclass)) + ($self->instance_metaclass->isa($super_meta->instance_metaclass)) || confess $self->name . "->meta->instance_metaclass => (" . ($self->instance_metaclass) . ")" . " is not compatible with the " . - $class_name . "->meta->instance_metaclass => (" . ($meta->instance_metaclass) . ")"; + $superclass_name . "->meta->instance_metaclass => (" . ($super_meta->instance_metaclass) . ")"; } } -# backwards compat for stevan's inability to spell ;) -sub check_metaclass_compatability { - my $self = shift; - $self->check_metaclass_compatibility(@_); -} - ## ANON classes { @@ -319,57 +313,6 @@ sub method_metaclass { $_[0]->{'method_metaclass'} } sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} } sub instance_metaclass { $_[0]->{'instance_metaclass'} } -sub get_method_map { - my $self = shift; - - my $class_name = $self->name; - - my $current = Class::MOP::check_package_cache_flag($class_name); - - if (defined $self->{'_package_cache_flag'} && $self->{'_package_cache_flag'} == $current) { - return $self->{'methods'} ||= {}; - } - - $self->{_package_cache_flag} = $current; - - my $map = $self->{'methods'} ||= {}; - - 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, - associated_metaclass => $self, - package_name => $class_name, - name => $symbol, - ); - } - - return $map; -} - # Instance Construction & Cloning sub new_object { @@ -477,7 +420,8 @@ sub rebless_instance { || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't."; # rebless! - $meta_instance->rebless_instance_structure($instance, $self); + # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8 + $meta_instance->rebless_instance_structure($_[1], $self); foreach my $attr ( $self->compute_all_applicable_attributes ) { if ( $attr->has_value($instance) ) { @@ -675,7 +619,7 @@ sub add_method { $method = $self->find_next_method_by_name($method_name); # die if it does not exist (defined $method) - || confess "The method '$method_name' is not found in the inheritance hierarchy for class " . $self->name; + || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name; # and now make sure to wrap it # even if it is already wrapped # because we need a new sub ref @@ -897,7 +841,7 @@ sub update_meta_instance_dependencies { sub add_meta_instance_dependencies { my $self = shift; - $self->remove_meta_instance_depdendencies; + $self->remove_meta_instance_dependencies; my @attrs = $self->compute_all_applicable_attributes(); @@ -911,7 +855,7 @@ sub add_meta_instance_dependencies { $self->{meta_instance_dependencies} = \@classes; } -sub remove_meta_instance_depdendencies { +sub remove_meta_instance_dependencies { my $self = shift; if ( my $classes = delete $self->{meta_instance_dependencies} ) { @@ -1028,108 +972,43 @@ sub is_pristine { sub is_mutable { 1 } sub is_immutable { 0 } -# NOTE: -# Why I changed this (groditi) -# - One Metaclass may have many Classes through many Metaclass instances -# - One Metaclass should only have one Immutable Transformer instance -# - Each Class may have different Immutabilizing options -# - Therefore each Metaclass instance may have different Immutabilizing options -# - We need to store one Immutable Transformer instance per Metaclass -# - We need to store one set of Immutable Transformer options per Class -# - Upon make_mutable we may delete the Immutabilizing options -# - We could clean the immutable Transformer instance when there is no more -# immutable Classes of that type, but we can also keep it in case -# another class with this same Metaclass becomes immutable. It is a case -# of trading of storing an instance to avoid unnecessary instantiations of -# Immutable Transformers. You may view this as a memory leak, however -# Because we have few Metaclasses, in practice it seems acceptable -# - To allow Immutable Transformers instances to be cleaned up we could weaken -# the reference stored in $IMMUTABLE_TRANSFORMERS{$class} and ||= should DWIM +sub immutable_transformer { $_[0]->{immutable_transformer} } +sub _set_immutable_transformer { $_[0]->{immutable_transformer} = $_[1] } { - - my %IMMUTABLE_TRANSFORMERS; - my %IMMUTABLE_OPTIONS; - - 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 ){ - return $IMMUTABLE_TRANSFORMERS{$self->name} ||= $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; - } -} - -sub create_immutable_transformer { - my $self = shift; - my $class = Class::MOP::Immutable->new($self, { + my %Default_Immutable_Options = ( read_only => [qw/superclasses/], - cannot_call => [qw/ - add_method - alias_method - remove_method - add_attribute - remove_attribute - remove_package_symbol - /], - memoize => { - class_precedence_list => 'ARRAY', - linearized_isa => 'ARRAY', # FIXME perl 5.10 memoizes this on its own, no need? - get_all_methods => 'ARRAY', - get_all_method_names => 'ARRAY', - #get_all_attributes => 'ARRAY', # it's an alias, no need, but maybe in the future - compute_all_applicable_attributes => 'ARRAY', - get_meta_instance => 'SCALAR', - get_method_map => 'SCALAR', + cannot_call => [ + qw/ + add_method + alias_method + remove_method + add_attribute + remove_attribute + remove_package_symbol + / + ], + memoize => { + class_precedence_list => 'ARRAY', + # FIXME perl 5.10 memoizes this on its own, no need? + linearized_isa => 'ARRAY', + get_all_methods => 'ARRAY', + get_all_method_names => 'ARRAY', + compute_all_applicable_attributes => 'ARRAY', + get_meta_instance => 'SCALAR', + get_method_map => 'SCALAR', }, + # NOTE: - # this is ugly, but so are typeglobs, + # this is ugly, but so are typeglobs, # so whattayahgonnadoboutit # - SL - wrapped => { + 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'; + confess "Cannot add package symbols to an immutable metaclass" + unless ( caller(2) )[3] eq + 'Class::MOP::Package::get_package_symbol'; # This is a workaround for a bug in 5.8.1 which thinks that # goto $original->body @@ -1138,8 +1017,32 @@ sub create_immutable_transformer { goto $body; }, }, - }); - return $class; + ); + + sub make_immutable { + my $self = shift; + + return if $self->is_immutable; + + my $transformer = $self->immutable_transformer + || Class::MOP::Immutable->new( + $self, + %Default_Immutable_Options, + @_ + ); + + $self->_set_immutable_transformer($transformer); + + $transformer->make_metaclass_immutable; + } +} + +sub make_mutable { + my $self = shift; + + return if $self->is_mutable; + + $self->immutable_transformer->make_metaclass_mutable; } 1; @@ -1160,478 +1063,493 @@ Class::MOP::Class - Class Meta Object # use this for introspection ... # add a method to Foo ... - Foo->meta->add_method('bar' => sub { ... }) + Foo->meta->add_method( 'bar' => sub {...} ) - # get a list of all the classes searched - # the method dispatcher in the correct order - Foo->meta->class_precedence_list() + # get a list of all the classes searched + # the method dispatcher in the correct order + Foo->meta->class_precedence_list() - # remove a method from Foo - Foo->meta->remove_method('bar'); + # remove a method from Foo + Foo->meta->remove_method('bar'); # or use this to actually create classes ... - Class::MOP::Class->create('Bar' => ( - version => '0.01', - superclasses => [ 'Foo' ], - attributes => [ - Class::MOP:::Attribute->new('$bar'), - Class::MOP:::Attribute->new('$baz'), - ], - methods => { - calculate_bar => sub { ... }, - construct_baz => sub { ... } - } - )); + Class::MOP::Class->create( + 'Bar' => ( + version => '0.01', + superclasses => ['Foo'], + attributes => [ + Class::MOP:: : Attribute->new('$bar'), + Class::MOP:: : Attribute->new('$baz'), + ], + methods => { + calculate_bar => sub {...}, + construct_baz => sub {...} + } + ) + ); =head1 DESCRIPTION -This is the largest and currently most complex part of the Perl 5 -meta-object protocol. It controls the introspection and -manipulation of Perl 5 classes (and it can create them too). The +The Class Protocol is the largest and most complex part of the +Class::MOP meta-object protocol. It controls the introspection and +manipulation of Perl 5 classes, and it can create them as well. The best way to understand what this module can do, is to read the -documentation for each of it's methods. +documentation for each of its methods. =head1 INHERITANCE -B is a subclass of L +C is a subclass of L. =head1 METHODS -=head2 Self Introspection +=head2 Class construction + +These methods all create new C objects. These +objects can represent existing classes, or they can be used to create +new classes from scratch. + +The metaclass object for a given class is a singleton. If you attempt +to create a metaclass for the same class twice, you will just get the +existing object. =over 4 -=item B +=item B<< Class::MOP::Class->create($package_name, %options) >> -This will return a B instance which is related -to this class. Thereby allowing B to actually -introspect itself. +This method creates a new C object with the given +package name. It accepts a number of options. -As with B, B will actually -bootstrap this module by installing a number of attribute meta-objects -into it's metaclass. This will allow this class to reap all the benifits -of the MOP when subclassing it. +=over 8 -=back +=item * version -=head2 Class construction +An optional version number for the newly created package. -These methods will handle creating B objects, -which can be used to both create new classes, and analyze -pre-existing classes. +=item * authority -This module will internally store references to all the instances -you create with these methods, so that they do not need to be -created any more than nessecary. Basically, they are singletons. +An optional authority for the newly created package. -=over 4 +=item * superclasses -=item B ?$version, - authority =E ?$authority, - superclasses =E ?@superclasses, - methods =E ?%methods, - attributes =E ?%attributes)> +An optional array reference of superclass names. -This returns a B object, bringing the specified -C<$package_name> into existence and adding any of the C<$version>, -C<$authority>, C<@superclasses>, C<%methods> and C<%attributes> to -it. +=item * methods -=item B ?@superclasses, - methods =E ?%methods, - attributes =E ?%attributes)> +An optional hash reference of methods for the class. The keys of the +hash reference are method names, and values are subroutine references. -This will create an anonymous class, it works much like C but -it does not need a C<$package_name>. Instead it will create a suitably -unique package name for you to stash things into. +=item * attributes -On very important distinction is that anon classes are destroyed once -the metaclass they are attached to goes out of scope. In the DESTROY -method, the created package will be removed from the symbol table. +An optional array reference of attributes. -It is also worth noting that any instances created with an anon-class -will keep a special reference to the anon-meta which will prevent the -anon-class from going out of scope until all instances of it have also -been destroyed. This however only works for HASH based instance types, -as we use a special reserved slot (C<__MOP__>) to store this. +An attribute can be passed as an existing L +object, I or as a hash reference of options which will be passed +to the attribute metaclass's constructor. -=item B +=back -This initializes and returns returns a B object for -a given a C<$package_name>. If a metaclass already exists for the -package, it simply returns it instead of creating a new one. +=item B<< Class::MOP::Class->create_anon_class(%options) >> -=item B +This method works just like C<< Class::MOP::Class->create >> but it +creates an "anonymous" class. In fact, the class does have a name, but +that name is a unique name generated internally by this module. -This will construct an instance of B, it is -here so that we can actually "tie the knot" for B -to use C once all the bootstrapping is done. This -method is used internally by C and should never be called -from outside of that method really. +It accepts the same C, C, and C +parameters that C accepts. -=item B +Anonymous classes are destroyed once the metaclass they are attached +to goes out of scope, and will be removed from Perl's internal symbol +table. -This method is called as the very last thing in the -C method. This will check that the -metaclass you are creating is compatible with the metaclasses of all -your ancestors. For more inforamtion about metaclass compatibility -see the C section in L. +All instances of an anonymous class keep a special reference to the +metaclass object, which prevents the metaclass from going out of scope +while any instances exist. -=item B +This only works if the instance if based on a hash reference, however. -This will reset the package cache flag for this particular metaclass -it is basically the value of the C -function. This is very rarely needed from outside of C -but in some cases you might want to use it, so it is here. +=item B<< Class::MOP::Class->initialize($package_name, %options) >> -=item B +This method will initialize a C object for the +named package. Unlike C, this method I create a new +class. -Clears the package cache flag to announce to the internals that we need -to rebuild the method map. +The purpose of this method is to retrieve a C +object for introspecting an existing class. -=item B +If an existing C object exists for the named +package, it will be returned, and any options provided will be +ignored! -Registers this class as dependent on its superclasses. +If the object does not yet exist, it will be created. -Only superclasses from which this class inherits attributes will be added. +The valid options that can be passed to this method are +C, C, +C, and C. These are all +optional, and default to the appropriate class in the C +distribution. -=item B +=back -Unregisters this class from its superclasses. +=head2 Object instance construction and cloning -=item B +These methods are all related to creating and/or cloning object +instances. -Reregisters if necessary. +=over 4 + +=item B<< $metaclass->clone_object($instance, %params) >> -=item B $metaclass +This method clones an existing object instance. Any parameters you +provide are will override existing attribute values in the object. -Registers the class as having a meta instance dependent on this class. +This is a convenience method for cloning an object instance, then +blessing it into the appropriate package. -=item B $metaclass +You could implement a clone method in your class, using this method: -Remove the class from the list of dependent classes. + sub clone { + my ($self, %params) = @_; + $self->meta->clone_object($self, %params); + } -=item B +=item B<< $metaclass->rebless_instance($instance, %params) >> -Clears the cached meta instance for this metaclass and all of the registered -classes with dependent meta instances. +This method changes the class of C<$instance> to the metaclass's class. -Called by C and C to recalculate the attribute -slots. +You can only rebless an instance into a subclass of its current +class. If you pass any additional parameters, these will be treated +like constructor parameters and used to initialize the object's +attributes. Any existing attributes that are already set will be +overwritten. -=item B +=item B<< $metaclass->new_object(%params) >> -Used by C. +This method is used to create a new object of the metaclass's +class. Any parameters you provide are used to initialize the +instance's attributes. + +=item B<< $metaclass->instance_metaclass >> + +Returns the class name of the instance metaclass, see +L for more information on the instance +metaclasses. + +=item B<< $metaclass->get_meta_instance >> + +Returns an instance of the C to be used in the +construction of a new instance of the class. =back -=head2 Object instance construction and cloning +=head2 Informational predicates -These methods are B, it is up to you whether you want -to use them or not. +These are a few predicate methods for asking information about the +class itself. =over 4 -=item B +=item B<< $metaclass->is_anon_class >> -Returns the class name of the instance metaclass, see L -for more information on the instance metaclasses. +This returns true if the class was created by calling C<< +Class::MOP::Class->create_anon_class >>. -=item B +=item B<< $metaclass->is_mutable >> -Returns an instance of L to be used in the construction -of a new instance of the class. +This returns true if the class is still mutable. -=item B +=item B<< $metaclass->is_immutable >> -Called by C if necessary. +This returns true if the class has been made immutable. -=item B +=item B<< $metaclass->is_pristine >> -This is a convience method for creating a new object of the class, and -blessing it into the appropriate package as well. Ideally your class -would call a C this method like so: +A class is I pristine if it has non-inherited attributes or if it +has any generated methods. - sub MyClass::new { - my ($class, %param) = @_; - $class->meta->new_object(%params); - } - -=item B +=back -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. +=head2 Inheritance Relationships -This will construct an 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. +=over 4 -=item B +=item B<< $metaclass->superclasses(@superclasses) >> -This is a convience method for cloning an object instance, then -blessing it into the appropriate package. This method will call -C, which performs a shallow copy of the object, -see that methods documentation for more details. Ideally your -class would call a C this method like so: +This is a read-write accessor which represents the superclass +relationships of the metaclass's class. - sub MyClass::clone { - my ($self, %param) = @_; - $self->meta->clone_object($self, %params); - } +This is basically sugar around getting and setting C<@ISA>. -=item B +=item B<< $metaclass->class_precedence_list >> -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. +This returns a list of all of the class's ancestor classes. The +classes are returned in method dispatch order. -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). +=item B<< $metaclass->linearized_isa >> -As of 0.11, this method will clone the C<$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. +This returns a list based on C but with all +duplicates removed. -=item B +=item B<< $metaclass->subclasses >> -This will change the class of C<$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. +This returns a list of subclasses for this class. =back -=head2 Informational +=head2 Method introspection and creation -These are a few predicate methods for asking information about the class. +These methods allow you to introspect a class's methods, as well as +add, remove, or change methods. + +Determining what is truly a method in a Perl 5 class requires some +heuristics (aka guessing). + +Methods defined outside the package with a fully qualified name (C) will be included. Similarly, methods named +with a fully qualified name using L are also included. + +However, we attempt to ignore imported functions. + +Ultimately, we are using heuristics to determine what truly is a +method in a class, and these heuristics may get the wrong answer in +some edge cases. However, for most "normal" cases the heuristics work +correctly. =over 4 -=item B +=item B<< $metaclass->get_method($method_name) >> -This returns true if the class is a C created anon class. +This will return a L for the specified +C<$method_name>. If the class does not have the specified method, it +returns C -=item B +=item B<< $metaclass->has_method($method_name) >> -This returns true if the class is still mutable. +Returns a boolean indicating whether or not the class defines the +named method. It does not include methods inherited from parent +classes. -=item B +=item B<< $metaclass->get_method_map >> -This returns true if the class has been made immutable. +Returns a hash reference representing the methods defined in this +class. The keys are method names and the values are +L objects. -=item B +=item B<< $metaclass->get_method_list >> -Checks whether the class has any data that will be lost if C is -called. +This will return a list of method I for all methods defined in +this class. -=back +=item B<< $metaclass->get_all_methods >> -=head2 Inheritance Relationships +This will traverse the inheritance hierarchy and return a list of all +the L objects for this class and its parents. -=over 4 +=item B<< $metaclass->find_method_by_name($method_name) >> -=item B +This will return a L for the specified +C<$method_name>. If the class does not have the specified method, it +returns C -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. +Unlike C, this method I look for the named method in +superclasses. -=item B +=item B<< $metaclass->get_all_method_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. +This will return a list of method I for all of this class's +methods, including inherited methods. -=item B +=item B<< $metaclass->find_all_methods_by_name($method_name) >> -This returns a list based on C but with all -duplicates removed. +This method looks for the named method in the class and all of its +parents. It returns every matching method it finds in the inheritance +tree, so it returns a list of methods. -=item B +Each method is returned as a hash reference with three keys. The keys +are C, C, and C. The C key has a +L object as its value. -This returns a list of subclasses for this class. +The list of methods is distinct. -=back +=item B<< $metaclass->find_next_method_by_name($method_name) >> -=head2 Methods +This method returns the first method in any superclass matching the +given name. It is effectively the method that C +would dispatch to. -=over 4 +=item B<< $metaclass->add_method($method_name, $method) >> -=item B +This method takes a method name and a subroutine reference, and adds +the method to the class. -Returns a HASH ref of name to L instance mapping -for this class. +The subroutine reference can be a L, and you are +strongly encouraged to pass a meta method object instead of a code +reference. If you do so, that object gets stored as part of the +class's method map directly. If not, the meta information will have to +be recreated later, and may be incorrect. -=item B +If you provide a method object, this method will clone that object if +the object's package name does not match the class name. This lets us +track the original source of any methods added from other classes +(notably Moose roles). -Returns the class name of the method metaclass, see L -for more information on the method metaclasses. +=item B<< $metaclass->remove_method($method_name) >> -=item B +Remove the named method from the class. This method returns the +L object for the method. -Wrap a code ref (C<$attrs{body>) with C. +=back -=item B +=head2 Attribute introspection and creation -This will take a C<$method_name> and CODE reference or meta method -objectand install it into the class's package. +Because Perl 5 does not have a core concept of attributes in classes, +we can only return information about attributes which have been added +via this class's methods. We cannot discover information about +attributes which are defined in terms of "regular" Perl 5 methods. -You are strongly encouraged to pass a meta method object instead of a -code reference. If you do so, that object gets stored as part of the -class's method map, providing more useful information about the method -for introspection. +=over 4 -When you provide a method object, this method will clone that object -if the object's package name does not match the class name. This lets -us track the original source of any methods added from other classes -(notably Moose roles). +=item B<< $metaclass->get_attribute($attribute_name) >> -B: -This does absolutely nothing special to C<$method> -other than use B to make sure it is tagged with the -correct name, and therefore show up correctly in stack traces and -such. +This will return a L for the specified +C<$attribute_name>. If the class does not have the specified +attribute, it returns C -=item B +=item B<< $metaclass->has_attribute($attribute_name) >> -This just provides a simple way to check if the class implements -a specific C<$method_name>. It will I however, attempt to check -if the class inherits the method (use C for that). +Returns a boolean indicating whether or not the class defines the +named attribute. It does not include attributes inherited from parent +classes. -This will correctly handle functions defined outside of the package -that use a fully qualified name (C). +=item B<< $metaclass->get_attribute_map >> -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. +Returns a hash reference representing the attributes defined in this +class. The keys are attribute names and the values are +L objects. -This will attempt to correctly ignore functions imported from other -packages using B. It breaks down if the function imported -is an C<__ANON__> sub (such as with C), which very well -may be a valid method being applied to the class. +=item B<< $metaclass->get_attribute_list >> -In short, this method cannot always be trusted to determine if the -C<$method_name> is actually a method. However, it will DWIM about -90% of the time, so it's a small trade off I think. +This will return a list of attributes I for all attributes +defined in this class. -=item B +=item B<< $metaclass->get_all_attributes >> -This will return a Class::MOP::Method instance related to the specified -C<$method_name>, or return undef if that method does not exist. +This will traverse the inheritance hierarchy and return a list of all +the L objects for this class and its parents. -The Class::MOP::Method is codifiable, so you can use it like a normal -CODE reference, see L for more information. +This method can also be called as C. -=item B +=item B<< $metaclass->find_attribute_by_name($attribute_name) >> -This will return a L instance for the specified -C<$method_name>, or return undef if that method does not exist. +This will return a L for the specified +C<$attribute_name>. If the class does not have the specified +attribute, it returns C -Unlike C this will also look in the superclasses. +Unlike C, this attribute I look for the named +attribute in superclasses. -=item B +=item B<< $metaclass->add_attribute(...) >> -This will attempt to remove a given C<$method_name> from the class. -It will return the L instance that it has removed, -and will attempt to use B to clear the methods associated -name. +This method accepts either an existing L +object, or parameters suitable for passing to that class's C +method. -=item B +The attribute provided will be added to the class. -This will 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. +Any accessor methods defined by the attribute will be added to the +class when the attribute is added. -=item B +If an attribute of the same name already exists, the old attribute +will be removed first. -This will traverse the inheritance heirachy and return a list of all -the applicable L objects for this class. +=item B<< $metaclass->remove_attribute($attribute_name) >> -=item B +This will remove the named attribute from the class, and +L object. -Deprecated. +Removing an attribute also removes any accessor methods defined by the +attribute. -This method returns a list of hashes describing the all the methods of the -class. +However, note that removing an attribute will only affect I +object instances created for this class, not existing instances. + +=item B<< $metaclass->attribute_metaclass >> + +Returns the class name of the attribute metaclass for this class. By +default, this is L. for more information on + +=back + +=head2 Class Immutability + +Making a class immutable "freezes" the class definition. You can no +longer call methods which alter the class, such as adding or removing +methods or attributes. -Use L, which is easier/better/faster. This method predates -L. +Making a class immutable lets us optimize the class by inlining some +methods, and also allows us to optimize some methods on the metaclass +object itself. -=item B +The immutabilization system in L takes much greater advantage +of the inlining features than Class::MOP itself does. -This will traverse the inheritance heirachy and return a list of all the -applicable method names for this class. Duplicate names are removed, but the -order the methods come out is not defined. +=over 4 + +=item B<< $metaclass->make_immutable(%options) >> -=item B +This method will create an immutable transformer and uses it to make +the class and its metaclass object immutable. -This will traverse the inheritence hierarchy and locate all methods -with a given C<$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. +Details of how immutabilization works are in L +documentation. -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<< $metaclass->make_mutable >> -=item B +Calling this method reverse the immutabilization transformation. -This will return the first method to match a given C<$method_name> in -the superclasses, this is basically equivalent to calling -C, but it can be dispatched at runtime. +=item B<< $metaclass->immutable_transformer >> -=item B +If the class has been made immutable previously, this returns the +L object that was created to do the +transformation. -B: This method is now deprecated. Just use C -instead. +If the class was never made immutable, this method will die. =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. +Method modifiers are hooks which allow a method to be wrapped with +I, I and I method modifiers. Every time a +method is called, it's modifiers are also called. + +A class can modify its own methods, as well as methods defined in +parent classes. =head3 How method modifiers work? -Method modifiers work by wrapping the original method and then replacing -it in the 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: +Method modifiers work by wrapping the original method and then +replacing it in the class's symbol table. The wrappers will handle +calling all the modifiers in the appropriate order and preserving the +calling context for the original method. + +The return values of C and C modifiers are +ignored. This is because their purpose is B to filter the input +and output of the primary method (this is done with an I +modifier). + +This may seem like an odd restriction to some, but doing this allows +for simple code to be added at the beginning or end of a method call +without altering the function of the wrapped method or placing any +extra responsibility on the code of the modifier. + +Of course if you have more complex needs, you can use the C +modifier which allows you to change both the parameters passed to the +wrapped method, as well as its return value. + +Before and around modifiers are called in last-defined-first-called +order, while after modifiers are called in first-defined-first-called +order. So the call tree might looks something like this: before 2 before 1 @@ -1643,22 +1561,17 @@ the call tree might looks something like this: 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. +Of course there is a performance cost associated with method +modifiers, but we have made every effort to make that cost directly +proportional to the number of modifier features you utilize. The wrapping method does it's best to B do as much work as it absolutely needs to. In order to do this we have moved some of the performance costs to set-up time, where they are easier to amortize. -All this said, my benchmarks have indicated the following: +All this said, our benchmarks have indicated the following: simple wrapper with no modifiers 100% slower simple wrapper with simple before modifier 400% slower @@ -1667,158 +1580,60 @@ All this said, my benchmarks have indicated the following: 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 -their own. See L for more details. +comes with some cost. To put things in perspective, just doing a +simple C which does nothing but extract the name of the +method called and return it costs about 400% over a normal method +call. =over 4 -=item B +=item B<< $metaclass->add_before_method_modifier($method_name, $code) >> -Returns the class name of the attribute metaclass, see L -for more information on the attribute metaclasses. +This wraps the specified method with the supplied subroutine +reference. The modifier will be called as a method itself, and will +receive the same arguments as are passed to the method. -=item B +When the modifier exits, the wrapped method will be called. -This returns a HASH ref of name to attribute meta-object mapping. +The return value of the modifier will be ignored. -=item B +=item B<< $metaclass->add_after_method_modifier($method_name, $code) >> -This stores the C<$attribute_meta_object> (or creates one from the -C<$attribute_name> and C<%attribute_spec>) in the B -instance associated with the given class. Unlike methods, attributes -within the MOP are stored as meta-information only. They will be used -later to construct instances from (see C above). -More details about the attribute meta-objects can be found in the -L or the L -section. +This wraps the specified method with the supplied subroutine +reference. The modifier will be called as a method itself, and will +receive the same arguments as are passed to the method. -It should be noted that any accessor, reader/writer or predicate -methods which the C<$attribute_meta_object> has will be installed -into the class at this time. +When the wrapped methods exits, the modifier will be called. -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. +The return value of the modifier will be ignored. -=item B +=item B<< $metaclass->add_around_method_modifier($method_name, $code) >> -Checks to see if this class has an attribute by the name of -C<$attribute_name> and returns a boolean. +This wraps the specified method with the supplied subroutine +reference. -=item B +The first argument passed to the modifier will be a subroutine +reference to the wrapped method. The second argument is the object, +and after that come any arguments passed when the method is called. -Returns the attribute meta-object associated with C<$attribute_name>, -if none is found, it will return undef. +The around modifier can choose to call the original method, as well as +what arguments to pass if it does so. -=item B - -This will remove the attribute meta-object stored at -C<$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 -any existing instances of the class. - -It should be noted that any accessor, reader/writer or predicate -methods which the attribute meta-object stored at C<$attribute_name> -has will be removed from the class at this time. This B make -these attributes somewhat inaccessable in previously created -instances. But if you are crazy enough to do this at runtime, then -you are crazy enough to deal with something like this :). - -=item B - -This returns a list of attribute names which are defined in the local -class. If you want a list of all applicable attributes for a class, -use the C method. - -=item B - -=item B - -This will traverse the inheritance heirachy and return a list of all -the applicable L objects for this class. - -C is an alias for consistency with C. - -=item B - -This method will traverse the inheritance heirachy and find the -first attribute whose name matches C<$attr_name>, then return it. -It will return undef if nothing is found. +The return value of the modifier is what will be seen by the caller. =back -=head2 Class Immutability +=head2 Introspection =over 4 -=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 - -This method will reverse tranforamtion upon the class which -made it immutable. - -=item B - -Return a transformer suitable for making this class immutable or, if this -class is immutable, the transformer used to make it immutable. - -=item B - -If the class is immutable, return the options used to make it immutable. +=item B<< Class::MOP::Class->meta >> -=item B +This will return a L instance for this class. -Create a transformer suitable for making this class immutable +It should also be noted that L will actually bootstrap +this module by installing a number of attribute meta-objects into its +metaclass. =back @@ -1828,7 +1643,7 @@ Stevan Little Estevan@iinteractive.comE =head1 COPYRIGHT AND LICENSE -Copyright 2006-2008 by Infinity Interactive, Inc. +Copyright 2006-2009 by Infinity Interactive, Inc. L