X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FClass%2FMOP%2FClass.pm;h=bcdb18de101d2060a81ea37e2e4bded574a6df70;hb=052c2a1a011f60e34ce109efdab03995dcf7bfb5;hp=988c73531af0d5a433209a00ade0670c96220079;hpb=c50c603e0b03ecf8d9ce888b94809240366c1bc0;p=gitmo%2FClass-MOP.git
diff --git a/lib/Class/MOP/Class.pm b/lib/Class/MOP/Class.pm
index 988c735..bcdb18d 100644
--- a/lib/Class/MOP/Class.pm
+++ b/lib/Class/MOP/Class.pm
@@ -9,30 +9,98 @@ use Scalar::Util 'blessed', 'reftype';
use Sub::Name 'subname';
use B 'svref_2object';
-our $VERSION = '0.01';
+our $VERSION = '0.14';
-# Self-introspection
+use Class::MOP::Instance;
-sub meta { $_[0]->initialize($_[0]) }
+# Self-introspection
+
+sub meta { Class::MOP::Class->initialize(blessed($_[0]) || $_[0]) }
# Creation
-{
+#{
# Metaclasses are singletons, so we cache them here.
# there is no need to worry about destruction though
# because they should die only when the program dies.
# After all, do package definitions even get reaped?
- my %METAS;
+ my %METAS;
+
+ # means of accessing all the metaclasses that have
+ # been initialized thus far (for mugwumps obj browser)
+ sub get_all_metaclasses { %METAS }
+ sub get_all_metaclass_instances { values %METAS }
+ sub get_all_metaclass_names { keys %METAS }
+
sub initialize {
- my ($class, $package_name) = @_;
+ 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, @_);
+ }
+
+ # 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";
- $METAS{$package_name} ||= bless {
- '$:pkg' => $package_name,
- '%:attrs' => {}
- } => blessed($class) || $class;
+ || 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 $METAS{$package_name}
+ if exists $METAS{$package_name} && defined $METAS{$package_name};
+ $class = blessed($class) || $class;
+ # now create the metaclass
+ my $meta;
+ if ($class =~ /^Class::MOP::/) {
+ $meta = bless {
+ '$:package' => $package_name,
+ '%:attributes' => {},
+ '$: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 = bless $class->meta->construct_instance(%options) => $class
+ }
+ # and check the metaclass compatibility
+ $meta->check_metaclass_compatability();
+ $METAS{$package_name} = $meta;
}
-}
+
+ sub check_metaclass_compatability {
+ my $self = shift;
+
+ # this is always okay ...
+ return if blessed($self) eq 'Class::MOP::Class';
+
+ my @class_list = $self->class_precedence_list;
+ shift @class_list; # shift off $self->name
+
+ foreach my $class_name (@class_list) {
+ my $meta = $METAS{$class_name} || next;
+ ($self->isa(blessed($meta)))
+ || confess $self->name . "->meta => (" . (blessed($self)) . ")" .
+ " is not compatible with the " .
+ $class_name . "->meta => (" . (blessed($meta)) . ")";
+ }
+ }
+#}
sub create {
my ($class, $package_name, $package_version, %options) = @_;
@@ -44,6 +112,11 @@ sub create {
eval $code;
confess "creation of $package_name failed : $@" if $@;
my $meta = $class->initialize($package_name);
+
+ $meta->add_method('meta' => sub {
+ Class::MOP::Class->initialize(blessed($_[0]) || $_[0]);
+ });
+
$meta->superclasses(@{$options{superclasses}})
if exists $options{superclasses};
# NOTE:
@@ -64,35 +137,92 @@ sub create {
return $meta;
}
-# Instance Construction
+{
+ # NOTE:
+ # this should be sufficient, if you have a
+ # use case where it is not, write a test and
+ # I will change it.
+ my $ANON_CLASS_SERIAL = 0;
+
+ sub create_anon_class {
+ my ($class, %options) = @_;
+ my $package_name = 'Class::MOP::Class::__ANON__::SERIAL::' . ++$ANON_CLASS_SERIAL;
+ return $class->create($package_name, '0.00', %options);
+ }
+}
+
+## Attribute readers
+
+# NOTE:
+# 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'} }
+
+# 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 $instance = $class->get_meta_instance->create_instance();
+ foreach my $attr ($class->compute_all_applicable_attributes()) {
+ $attr->initialize_instance_slot($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 $instance = shift;
+ (blessed($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');
+ bless $class->clone_instance($instance, @_) => blessed($instance);
+}
+
+sub clone_instance {
+ my ($class, $instance, %params) = @_;
+ (blessed($instance))
+ || confess "You can only clone instances, \$self is not a blessed instance";
+ my $clone = { %$instance, %params };
+ return $clone;
+}
+
# Informational
-sub name { $_[0]->{'$:pkg'} }
+# &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'};
+ ${$self->get_package_variable('$VERSION')};
}
# Inheritance
@@ -104,7 +234,7 @@ sub superclasses {
my @supers = @_;
@{$self->name . '::ISA'} = @supers;
}
- @{$self->name . '::ISA'};
+ @{$self->name . '::ISA'};
}
sub class_precedence_list {
@@ -114,12 +244,16 @@ 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 {
- $self->initialize($_)->class_precedence_list()
+ # OPTIMIZATION NOTE:
+ # we grab the metaclass from the %METAS
+ # hash here to save the initialize() call
+ # if we can, but it is not always possible
+ ($METAS{$_} || $self->initialize($_))->class_precedence_list()
} $self->superclasses()
);
}
@@ -131,35 +265,115 @@ sub add_method {
(defined $method_name && $method_name)
|| confess "You must define a method name";
# use reftype here to allow for blessed subs ...
- (reftype($method) && reftype($method) eq 'CODE')
+ ('CODE' eq (reftype($method) || ''))
|| confess "Your code block must be a CODE reference";
my $full_method_name = ($self->name . '::' . $method_name);
-
+
+ $method = $self->method_metaclass->wrap($method) unless blessed($method);
+
no strict 'refs';
no warnings 'redefine';
*{$full_method_name} = subname $full_method_name => $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 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 ($method) {
+ # make sure this method even exists ...
+ ($self->find_next_method_by_name($method_name))
+ || confess "The method '$method_name' is not found in the inherience hierarchy for this class";
+ # if so, then create a local which just
+ # calls the next applicable method ...
+ $self->add_method($method_name => sub {
+ $self->find_next_method_by_name($method_name)->(@_);
+ });
+ $method = $self->get_method($method_name);
+ }
+
+ # now make sure we wrap it properly
+ # (if it isnt already)
+ unless ($method->isa('Class::MOP::Method::Wrapped')) {
+ $method = Class::MOP::Method::Wrapped->wrap($method);
+ $self->add_method($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 && $method_name)
+ || confess "You must define a method name";
+ # use reftype here to allow for blessed subs ...
+ ('CODE' eq (reftype($method) || ''))
+ || confess "Your code block must be a CODE reference";
+ my $full_method_name = ($self->name . '::' . $method_name);
+
+ $method = $self->method_metaclass->wrap($method) unless blessed($method);
- no strict 'refs';
- return 0 if !defined(&{$sub_name});
- return 0 if $_find_subroutine_package_name->(\&{$sub_name}) ne $self->name &&
- $_find_subroutine_name->(\&{$sub_name}) ne '__ANON__';
- return 1;
- }
+ no strict 'refs';
+ no warnings 'redefine';
+ *{$full_method_name} = $method;
+}
+sub has_method {
+ my ($self, $method_name) = @_;
+ (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});
+ my $method = \&{$sub_name};
+ return 0 if (svref_2object($method)->GV->STASH->NAME || '') ne $self->name &&
+ (svref_2object($method)->GV->NAME || '') ne '__ANON__';
+
+ # at this point we are relatively sure
+ # it is our method, so we bless/wrap it
+ $self->method_metaclass->wrap($method) unless blessed($method);
+ return 1;
}
sub get_method {
@@ -167,10 +381,10 @@ sub get_method {
(defined $method_name && $method_name)
|| confess "You must define a method name";
+ return unless $self->has_method($method_name);
+
no strict 'refs';
- return \&{$self->name . '::' . $method_name}
- if $self->has_method($method_name);
- return; # <- make sure to return undef
+ return \&{$self->name . '::' . $method_name};
}
sub remove_method {
@@ -241,48 +455,85 @@ 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
sub add_attribute {
- my ($self,$attribute) = @_;
- (blessed($attribute) && $attribute->isa('Class::MOP::Attribute'))
- || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
- $attribute->install_accessors($self);
- $self->{'%:attrs'}->{$attribute->name} = $attribute;
+ my $self = shift;
+ # either we have an attribute object already
+ # or we need to create one from the args provided
+ 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)";
+ $attribute->attach_to_class($self);
+ $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);
+ # OPTIMIZATION NOTE:
+ # we used to say `if $self->has_attribute($attribute_name)`
+ # here, but since get_attribute is called so often, we
+ # eliminate the function call here
+ return $self->{'%:attributes'}->{$attribute_name}
+ if exists $self->{'%:attributes'}->{$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;
- $removed_attribute->remove_accessors($self);
+ 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'}};
+ # OPTIMIZATION NOTE:
+ # We don't use get_attribute_map here because
+ # we ask for the attribute list quite often
+ # in compute_all_applicable_attributes, so
+ # eliminating the function call helps
+ keys %{$self->{'%:attributes'}};
}
sub compute_all_applicable_attributes {
@@ -297,20 +548,101 @@ sub compute_all_applicable_attributes {
next if $seen_class{$class};
$seen_class{$class}++;
# fetch the meta-class ...
- my $meta = $self->initialize($class);
+ # OPTIMIZATION NOTE:
+ # we grab the metaclass from the %METAS
+ # hash here to save the initialize() call
+ my $meta = $METAS{$class};
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;
}
+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;
+}
+
+# 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 {
+ my $e;
+ {
+ # NOTE:
+ # We HAVE to localize $@ or all
+ # hell breaks loose. It is not
+ # good, believe me, not good.
+ local $@;
+ eval $sigil . $self->name . '::' . $name;
+ $e = $@ if $@;
+ }
+ confess "Could not create package variable ($variable) because : $e" if $e;
+ }
+}
+
+sub has_package_variable {
+ my ($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 =~ /^(.)(.*)$/);
+ my ($ref, $e);
+ {
+ # NOTE:
+ # We HAVE to localize $@ or all
+ # hell breaks loose. It is not
+ # good, believe me, not good.
+ local $@;
+ $ref = eval '\\' . $sigil . $self->name . '::' . $name;
+ $e = $@ if $@;
+ }
+ confess "Could not get the package variable ($variable) because : $e" if $e;
+ # if we didn't die, then we can return it
+ return $ref;
+}
+
+sub remove_package_variable {
+ my ($self, $variable) = @_;
+ (defined $variable && $variable =~ /^[\$\@\%]/)
+ || confess "variable name does not have a sigil";
+ my ($sigil, $name) = ($variable =~ /^(.)(.*)$/);
+ no strict 'refs';
+ delete ${$self->name . '::'}{$name};
+}
1;
@@ -324,8 +656,43 @@ Class::MOP::Class - Class Meta Object
=head1 SYNOPSIS
+ # assuming that class Foo
+ # has been defined, you can
+
+ # use this for introspection ...
+
+ # add a method to Foo ...
+ Foo->meta->add_method('bar' => sub { ... })
+
+ # get a list of all the classes searched
+ # the method dispatcher in the correct order
+ Foo->meta->class_precedence_list()
+
+ # remove a method from Foo
+ Foo->meta->remove_method('bar');
+
+ # or use this to actually create classes ...
+
+ Class::MOP::Class->create('Bar' => '0.01' => (
+ superclasses => [ 'Foo' ],
+ attributes => [
+ Class::MOP:::Attribute->new('$bar'),
+ Class::MOP:::Attribute->new('$baz'),
+ ],
+ methods => {
+ calculate_bar => sub { ... },
+ construct_baz => sub { ... }
+ }
+ ));
+
=head1 DESCRIPTION
+This is the largest and currently most complex part of the Perl 5
+meta-object protocol. It controls the introspection and
+manipulation of Perl 5 classes (and it can create them too). The
+best way to understand what this module can do, is to read the
+documentation for each of it's methods.
+
=head1 METHODS
=head2 Self Introspection
@@ -334,14 +701,37 @@ Class::MOP::Class - Class Meta Object
=item B
-This allows Class::MOP::Class to actually introspect itself.
+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.
+
+=item B
+
+This will return an hash of all the metaclass instances that have
+been cached by B keyed by the package name.
+
+=item B
+
+This will return an array of all the metaclass instances that have
+been cached by B.
+
+=item B
+
+This will return an array of all the metaclass names that have
+been cached by B.
=back
=head2 Class construction
-These methods handle creating Class objects, which can be used to
-both create new classes, and analyze pre-existing ones.
+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
@@ -350,33 +740,117 @@ created any more than nessecary. Basically, they are singletons.
=over 4
=item B ?@superclasses,
- methods => ?%methods,
- attributes => ?%attributes)>
+ superclasses =E ?@superclasses,
+ methods =E ?%methods,
+ attributes =E ?%attributes)>
-This returns the basic Class object, bringing the specified
+This returns a B object, bringing the specified
C<$package_name> into existence and adding any of the
C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes>
to it.
+=item B ?@superclasses,
+ methods =E ?%methods,
+ attributes =E ?%attributes)>
+
+This will create an anonymous class, it works much like C but
+it does not need a C<$package_name>. Instead it will create a suitably
+unique package name for you to stash things into.
+
=item B
-This initializes a Class object for a given a C<$package_name>.
+This initializes and returns returns a B object
+for a given a C<$package_name>.
+
+=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
+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 Instance construction
+=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
+
+=item B
+
+=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) = @_;
+ $class->meta->new_object(%params);
+ }
+
+Of course the ideal place for this would actually be in C
+but that is considered bad style, so we do not do that.
+
=item B
+This method is used to construct an instace structure suitable for
+C-ing into your package of choice. It works in conjunction
+with the Attribute protocol to collect all applicable attributes.
+
This will construct and instance using a HASH ref as storage
(currently only HASH references are supported). This will collect all
-the applicable attribute meta-objects and layout out the fields in the
-HASH ref, it will then initialize them using either use the
-corresponding key in C<%params> or any default value or initializer
-found in the attribute meta-object.
+the applicable attributes and layout out the fields in the HASH ref,
+it will then initialize them using either use the corresponding key
+in C<%params> or any default value or initializer found in the
+attribute meta-object.
+
+=item B
+
+This is a convience method for cloning an object instance, then
+blessing it into the appropriate package. This method will call
+C, which performs a shallow copy of the object,
+see that methods documentation for more details. Ideally your
+class would call a C this method like so:
+
+ sub MyClass::clone {
+ my ($self, %param) = @_;
+ $self->meta->clone_object($self, %params);
+ }
+
+Of course the ideal place for this would actually be in C
+but that is considered bad style, so we do not do that.
+
+=item B
+
+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<$instance> structure shallowly,
+as opposed to the deep cloning implemented in prior versions. After much
+thought, research and discussion, I have decided that anything but basic
+shallow cloning is outside the scope of the meta-object protocol. I
+think Yuval "nothingmuch" Kogman put it best when he said that cloning
+is too I to be part of the MOP.
=back
@@ -386,13 +860,13 @@ found in the attribute meta-object.
=item B
-This is a read-only attribute which returns the package name that
-the Class is stored in.
+This is a read-only attribute which returns the package name for the
+given B instance.
=item B
This is a read-only attribute which returns the C<$VERSION> of the
-package the Class is stored in.
+package for the given B instance.
=back
@@ -403,13 +877,21 @@ package the Class is stored in.
=item B
This is a read-write attribute which represents the superclass
-relationships of this Class. Basically, it can get and set the
-C<@ISA> for you.
+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 the Class's ancestors in the same order
-in which method dispatch will be done.
+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.
=back
@@ -417,21 +899,34 @@ in which method dispatch will be done.
=over 4
+=item B
+
=item B
This will take a C<$method_name> and CODE reference to that
-C<$method> and install it into the Class.
+C<$method> and install it into the class's package.
-B : This does absolutely nothing special to C<$method>
+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
+This just provides a simple way to check if the class implements
a specific C<$method_name>. It will I however, attempt to check
-if the class inherits the method.
+if the class inherits the method (use C for that).
This will correctly handle functions defined outside of the package
that use a fully qualified name (C).
@@ -449,7 +944,7 @@ may be a valid method being applied to the class.
In short, this method cannot always be trusted to determine if the
C<$method_name> is actually a method. However, it will DWIM about
-90% of the time, so it's a small trade off IMO.
+90% of the time, so it's a small trade off I think.
=item B
@@ -458,7 +953,7 @@ or return undef if that method does not exist.
=item B
-This will attempt to remove a given C<$method_name> from the Class.
+This will attempt to remove a given C<$method_name> from the class.
It will return the CODE reference that it has removed, and will
attempt to use B to clear the methods associated name.
@@ -471,8 +966,8 @@ methods, use the C method.
=item B
-This will return a list of all the methods names this Class will
-support, taking into account inheritance. The list will be a list of
+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.
@@ -491,6 +986,110 @@ 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<$code> can or cannot do.
+
=back
=head2 Attributes
@@ -498,22 +1097,32 @@ once, and in the correct order.
It should be noted that since there is no one consistent way to define
the attributes of a class in Perl 5. These methods can only work with
the information given, and can not easily discover information on
-their own.
+their own. See L for more details.
=over 4
+=item B
+
+=item B
+
=item B
-This stores a C<$attribute_meta_object> in the Class object and
-associates it with the C<$attribute_name>. Unlike methods, attributes
-within the MOP are stored as meta-information only. They will be used
-later to construct instances from (see C above).
+This stores a C<$attribute_meta_object> in the B
+instance associated with the given class, and associates it with
+the C<$attribute_name>. Unlike methods, attributes within the MOP
+are stored as meta-information only. They will be used later to
+construct instances from (see C above).
More details about the attribute meta-objects can be found in the
-L section of this document.
+L or the L
+section.
+
+It should be noted that any accessor, reader/writer or predicate
+methods which the C<$attribute_meta_object> has will be installed
+into the class at this time.
=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<$attribute_name> and returns a boolean.
=item B
@@ -526,10 +1135,18 @@ if none is found, it will return undef.
This will remove the attribute meta-object stored at
C<$attribute_name>, then return the removed attribute meta-object.
-B Removing an attribute will only affect future instances of
+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<$attribute_name>
+has will be removed from the class at this time. This B make
+these attributes somewhat inaccessable in previously created
+instances. But if you are crazy enough to do this at runtime, then
+you are crazy enough to deal with something like this :).
+
=item B
This returns a list of attribute names which are defined in the local
@@ -538,17 +1155,56 @@ use the C method.
=item B
-This will traverse the inheritance heirachy and return a list of HASH
-references for all the applicable attributes for this class. The HASH
-references will contain the following information; the attribute name,
-the class which the attribute is associated with and the actual
-attribute meta-object.
+This will traverse the inheritance heirachy and return a list of all
+the applicable attributes for this class. It does not construct a
+HASH reference like C because all
+that same information is discoverable through the attribute
+meta-object itself.
+
+=item B
+
+This method will traverse the inheritance heirachy and find the
+first attribute whose name matches C<$attr_name>, then return it.
+It will return undef if nothing is found.
+
+=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
+
+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<$variable_name>
+implies.
+
+=item B
+
+This will return a reference to the package variable in
+C<$variable_name>.
+
+=item B
+
+Returns true (C<1>) if there is a package variable defined for
+C<$variable_name>, and false (C<0>) otherwise.
+
+=item B
+
+This will attempt to remove the package variable at C<$variable_name>.
=back
=head1 AUTHOR
-Stevan Little Estevan@iinteractive.comE
+Stevan Little Estevan@iinteractive.comE
=head1 COPYRIGHT AND LICENSE
@@ -559,4 +1215,4 @@ 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
+=cutchistian
\ No newline at end of file