use Scalar::Util 'blessed', 'reftype';
use Sub::Name 'subname';
use B 'svref_2object';
-use Clone ();
-our $VERSION = '0.04';
+our $VERSION = '0.14';
+
+use Class::MOP::Instance;
# Self-introspection
# 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 = 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;
+ (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, @_);
}
my $package_name = $options{':package'};
(defined $package_name && $package_name)
|| confess "You must pass a package name";
- return $METAS{$package_name} if exists $METAS{$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 $meta;
'$:package' => $package_name,
'%:attributes' => {},
'$:attribute_metaclass' => $options{':attribute_metaclass'} || 'Class::MOP::Attribute',
- '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method',
+ '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method',
+ '$:instance_metaclass' => $options{':instance_metaclass'} || 'Class::MOP::Instance',
} => $class;
}
else {
shift @class_list; # shift off $self->name
foreach my $class_name (@class_list) {
- my $meta = $METAS{$class_name};
+ 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) = @_;
return $meta;
}
+{
+ # 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:
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
# which will deal with the singletons
return $class->construct_class_instance(@_)
if $class->name->isa('Class::MOP::Class');
- bless $class->construct_instance(@_) => $class->name;
+ return $class->construct_instance(@_);
}
sub construct_instance {
my ($class, %params) = @_;
- my $instance = {};
+ my $instance = $class->get_meta_instance->create_instance();
foreach my $attr ($class->compute_all_applicable_attributes()) {
- my $init_arg = $attr->init_arg();
- # 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;
+ $attr->initialize_instance_slot($instance, \%params);
}
return $instance;
}
+sub get_meta_instance {
+ my $class = shift;
+ $class->{':instance_meta_object_cache'} ||= $class->instance_metaclass->new($class);
+}
+
sub clone_object {
my $class = shift;
my $instance = shift;
my ($class, $instance, %params) = @_;
(blessed($instance))
|| confess "You can only clone instances, \$self is not a blessed instance";
- # NOTE:
- # This will deep clone, which might
- # not be what you always want. So
- # the best thing is to write a more
- # controled &clone method locally
- # in the class (see Class::MOP)
- my $clone = Clone::clone($instance);
- foreach my $attr ($class->compute_all_applicable_attributes()) {
- my $init_arg = $attr->init_arg();
- # try to fetch the init arg from the %params ...
- $clone->{$attr->name} = $params{$init_arg}
- if exists $params{$init_arg};
- }
+ my $clone = { %$instance, %params };
return $clone;
}
sub version {
my $self = shift;
- no strict 'refs';
- ${$self->name . '::VERSION'};
+ ${$self->get_package_variable('$VERSION')};
}
# Inheritance
my @supers = @_;
@{$self->name . '::ISA'} = @supers;
}
- @{$self->name . '::ISA'};
+ @{$self->name . '::ISA'};
}
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()
);
}
(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;
}
+{
+ 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 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' => $method_modifier);
+ }
+
+ sub add_around_method_modifier {
+ my ($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 && $method_name)
|| confess "You must define a method name";
# use reftype here to allow for blessed subs ...
- (reftype($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);
+ 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} = $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 ($self, $method_name) = @_;
+ (defined $method_name && $method_name)
+ || confess "You must define a method name";
- sub has_method {
- my ($self, $method_name) = @_;
- (defined $method_name && $method_name)
- || confess "You must define a method name";
+ my $sub_name = ($self->name . '::' . $method_name);
- my $sub_name = ($self->name . '::' . $method_name);
-
- no strict 'refs';
- return 0 if !defined(&{$sub_name});
- return 0 if $_find_subroutine_package_name->(\&{$sub_name}) ne $self->name &&
- $_find_subroutine_name->(\&{$sub_name}) ne '__ANON__';
- return 1;
- }
-
+ 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 {
(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 {
next if $seen_class{$class};
$seen_class{$class}++;
# fetch the meta-class ...
- my $meta = $self->initialize($class);;
+ my $meta = $self->initialize($class);
push @methods => {
name => $method_name,
class => $class,
} 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
($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();
+ $attribute->install_accessors();
$self->get_attribute_map->{$attribute->name} = $attribute;
}
my ($self, $attribute_name) = @_;
(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);
+ # 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 {
(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;
}
sub get_attribute_list {
my $self = shift;
- keys %{$self->get_attribute_map};
+ # 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 {
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}++;
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 {
*{$self->name . '::' . $name} = $initial_value;
}
else {
- eval $sigil . $self->name . '::' . $name;
- confess "Could not create package variable ($variable) because : $@" if $@;
+ 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;
}
}
(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 $@;
+ my ($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
- # NOTE:
- # this is not ideal, better suggestions are welcome
- eval '\\' . $sigil . $self->name . '::' . $name;
+ return $ref;
}
sub remove_package_variable {
=head1 SYNOPSIS
+ # assuming that class Foo
+ # has been defined, you can
+
# use this for introspection ...
# add a method to Foo ...
into it's metaclass. This will allow this class to reap all the benifits
of the MOP when subclassing it.
+=item B<get_all_metaclasses>
+
+This will return an hash of all the metaclass instances that have
+been cached by B<Class::MOP::Class> keyed by the package name.
+
+=item B<get_all_metaclass_instances>
+
+This will return an array of all the metaclass instances that have
+been cached by B<Class::MOP::Class>.
+
+=item B<get_all_metaclass_names>
+
+This will return an array of all the metaclass names that have
+been cached by B<Class::MOP::Class>.
+
=back
=head2 Class construction
C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes>
to it.
+=item B<create_anon_class (superclasses =E<gt> ?@superclasses,
+ methods =E<gt> ?%methods,
+ attributes =E<gt> ?%attributes)>
+
+This will create an anonymous class, it works much like C<create> but
+it does not need a C<$package_name>. Instead it will create a suitably
+unique package name for you to stash things into.
+
=item B<initialize ($package_name)>
This initializes and returns returns a B<Class::MOP::Class> object
=over 4
+=item B<instance_metaclass>
+
+=item B<get_meta_instance>
+
=item B<new_object (%params)>
This is a convience method for creating a new object of the class, and
=item B<clone_object ($instance, %params)>
This is a convience method for cloning an object instance, then
-blessing it into the appropriate package. Ideally your class
-would call a C<clone> this method like so:
+blessing it into the appropriate package. This method will call
+C<clone_instance>, which performs a shallow copy of the object,
+see that methods documentation for more details. Ideally your
+class would call a C<clone> this method like so:
sub MyClass::clone {
my ($self, %param) = @_;
=item B<clone_instance($instance, %params)>
This method is a compliment of C<construct_instance> (which means if
-you override C<construct_instance>, you need to override this one too).
+you override C<construct_instance>, you need to override this one too),
+and clones the instance shallowly.
+
+The cloned structure returned is (like with C<construct_instance>) an
+unC<bless>ed HASH reference, it is your responsibility to then bless
+this cloned structure into the right class (which C<clone_object> will
+do for you).
-This method will clone the C<$instance> structure created by the
-C<construct_instance> method, and apply any C<%params> passed to it
-to change the attribute values. The structure returned is (like with
-C<construct_instance>) an unC<bless>ed 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<$instance> structure shallowly,
+as opposed to the deep cloning implemented in prior versions. After much
+thought, research and discussion, I have decided that anything but basic
+shallow cloning is outside the scope of the meta-object protocol. I
+think Yuval "nothingmuch" Kogman put it best when he said that cloning
+is too I<context-specific> to be part of the MOP.
=back
initialization and destruction where you only want the method called
once, and in the correct order.
+=item B<find_next_method_by_name ($method_name)>
+
+This will return the first method to match a given C<$method_name> in
+the superclasses, this is basically equivalent to calling
+C<SUPER::$method_name>, 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<before>, I<after> and I<around> 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<before> and I<after> modifiers are ignored. This is
+because thier purpose is B<not> to filter the input and output of the
+primary method (this is done with an I<around> 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<around> 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<InstanceCountingClass>, F<Perl6Attribute>,
+F<AttributesWithHistory> and F<C3MethodDispatchOrder>. 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<only> 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<AUTOLOAD> 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<add_before_method_modifier ($method_name, $code)>
+
+This will wrap the method at C<$method_name> and the supplied C<$code>
+will be passed the C<@_> arguments, and called before the original
+method is called. As specified above, the return value of the I<before>
+method modifiers is ignored, and it's ability to modify C<@_> is
+fairly limited. If you need to do either of these things, use an
+C<around> method modifier.
+
+=item B<add_after_method_modifier ($method_name, $code)>
+
+This will wrap the method at C<$method_name> so that the original
+method will be called, it's return values stashed, and then the
+supplied C<$code> will be passed the C<@_> arguments, and called.
+As specified above, the return value of the I<after> method
+modifiers is ignored, and it cannot modify the return values of
+the original method. If you need to do either of these things, use an
+C<around> method modifier.
+
+=item B<add_around_method_modifier ($method_name, $code)>
+
+This will wrap the method at C<$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<$code> can or cannot do.
+
=back
=head2 Attributes
that same information is discoverable through the attribute
meta-object itself.
+=item B<find_attribute_by_name ($attr_name)>
+
+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
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
projects / gitmo/Class-MOP.git / blobdiff