use strict;
use warnings;
+use Class::MOP::Method::Accessor;
+
use Carp 'confess';
-use Scalar::Util 'blessed';
+use Scalar::Util 'blessed', 'reftype', 'weaken';
-use Class::MOP::Class;
-use Class::MOP::Method;
+our $VERSION = '0.14';
+our $AUTHORITY = 'cpan:STEVAN';
-our $VERSION = '0.01';
+use base 'Class::MOP::Object';
-sub meta { Class::MOP::Class->initialize($_[0]) }
+sub meta {
+ require Class::MOP::Class;
+ Class::MOP::Class->initialize(blessed($_[0]) || $_[0]);
+}
+# NOTE: (meta-circularity)
+# This method will be replaced in the
+# boostrap section of Class::MOP, by
+# a new version which uses the
+# &Class::MOP::Class::construct_instance
+# method to build an attribute meta-object
+# which itself is described with attribute
+# meta-objects.
+# - Ain't meta-circularity grand? :)
sub new {
my $class = shift;
my $name = shift;
(defined $name && $name)
|| confess "You must provide a name for the attribute";
- (!exists $options{reader} && !exists $options{writer})
- || confess "You cannot declare an accessor and reader and/or writer functions"
- if exists $options{accessor};
+
+ $options{init_arg} = $name
+ if not exists $options{init_arg};
+
+ (is_default_a_coderef(\%options))
+ || confess("References are not allowed as default values, you must ".
+ "wrap then in a CODE reference (ex: sub { [] } and not [])")
+ if exists $options{default} && ref $options{default};
bless {
- name => $name,
- accessor => $options{accessor},
- reader => $options{reader},
- writer => $options{writer},
- init_arg => $options{init_arg},
- default => $options{default}
+ '$!name' => $name,
+ '$!accessor' => $options{accessor},
+ '$!reader' => $options{reader},
+ '$!writer' => $options{writer},
+ '$!predicate' => $options{predicate},
+ '$!clearer' => $options{clearer},
+ '$!init_arg' => $options{init_arg},
+ '$!default' => $options{default},
+ # keep a weakened link to the
+ # class we are associated with
+ '$!associated_class' => undef,
+ # and a list of the methods
+ # associated with this attr
+ '@!associated_methods' => [],
} => $class;
}
-sub name { (shift)->{name} }
+# NOTE:
+# this is a primative (and kludgy) clone operation
+# for now, it will be replaced in the Class::MOP
+# bootstrap with a proper one, however we know
+# that this one will work fine for now.
+sub clone {
+ my $self = shift;
+ my %options = @_;
+ (blessed($self))
+ || confess "Can only clone an instance";
+ return bless { %{$self}, %options } => blessed($self);
+}
-sub has_accessor { (shift)->{accessor} ? 1 : 0 }
-sub accessor { (shift)->{accessor} }
+sub initialize_instance_slot {
+ my ($self, $meta_instance, $instance, $params) = @_;
+ my $init_arg = $self->{'$!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)
+ if (!defined $val && defined $self->{'$!default'}) {
+ $val = $self->default($instance);
+ }
+ $meta_instance->set_slot_value($instance, $self->name, $val);
+}
-sub has_reader { (shift)->{reader} ? 1 : 0 }
-sub reader { (shift)->{reader} }
+# NOTE:
+# the next bunch of methods will get bootstrapped
+# away in the Class::MOP bootstrapping section
-sub has_writer { (shift)->{writer} ? 1 : 0 }
-sub writer { (shift)->{writer} }
+sub name { $_[0]->{'$!name'} }
-sub has_init_arg { (shift)->{init_arg} ? 1 : 0 }
-sub init_arg { (shift)->{init_arg} }
+sub associated_class { $_[0]->{'$!associated_class'} }
+sub associated_methods { $_[0]->{'@!associated_methods'} }
-sub has_default { (shift)->{default} ? 1 : 0 }
-sub default { (shift)->{default} }
+sub has_accessor { defined($_[0]->{'$!accessor'}) ? 1 : 0 }
+sub has_reader { defined($_[0]->{'$!reader'}) ? 1 : 0 }
+sub has_writer { defined($_[0]->{'$!writer'}) ? 1 : 0 }
+sub has_predicate { defined($_[0]->{'$!predicate'}) ? 1 : 0 }
+sub has_clearer { defined($_[0]->{'$!clearer'}) ? 1 : 0 }
+sub has_init_arg { defined($_[0]->{'$!init_arg'}) ? 1 : 0 }
+sub has_default { defined($_[0]->{'$!default'}) ? 1 : 0 }
-sub install_accessors {
- my ($self, $class) = @_;
- (blessed($class) && $class->isa('Class::MOP::Class'))
- || confess "You must pass a Class::MOP::Class instance (or a subclass)";
-
- if ($self->has_accessor()) {
- $class->add_method($self->accessor() => Class::MOP::Attribute::Accessor->wrap(sub {
- $_[0]->{$self->name} = $_[1] if scalar(@_) == 2;
- $_[0]->{$self->name};
- }));
- }
- else {
- if ($self->has_reader()) {
- $class->add_method($self->reader() => Class::MOP::Attribute::Accessor->wrap(sub {
- $_[0]->{$self->name};
- }));
- }
- if ($self->has_writer()) {
- $class->add_method($self->writer() => Class::MOP::Attribute::Accessor->wrap(sub {
- $_[0]->{$self->name} = $_[1];
- return;
- }));
- }
- }
+sub accessor { $_[0]->{'$!accessor'} }
+sub reader { $_[0]->{'$!reader'} }
+sub writer { $_[0]->{'$!writer'} }
+sub predicate { $_[0]->{'$!predicate'} }
+sub clearer { $_[0]->{'$!clearer'} }
+sub init_arg { $_[0]->{'$!init_arg'} }
+
+# end bootstrapped away method section.
+# (all methods below here are kept intact)
+
+sub get_read_method { $_[0]->reader || $_[0]->accessor }
+sub get_write_method { $_[0]->writer || $_[0]->accessor }
+
+sub is_default_a_coderef {
+ ('CODE' eq (reftype($_[0]->{'$!default'} || $_[0]->{default}) || ''))
+}
+
+sub default {
+ my ($self, $instance) = @_;
+ if (defined $instance && $self->is_default_a_coderef) {
+ # if the default is a CODE ref, then
+ # we pass in the instance and default
+ # can return a value based on that
+ # instance. Somewhat crude, but works.
+ return $self->{'$!default'}->($instance);
+ }
+ $self->{'$!default'};
}
-sub remove_accessors {
+# slots
+
+sub slots { (shift)->name }
+
+# class association
+
+sub attach_to_class {
my ($self, $class) = @_;
(blessed($class) && $class->isa('Class::MOP::Class'))
- || confess "You must pass a Class::MOP::Class instance (or a subclass)";
+ || confess "You must pass a Class::MOP::Class instance (or a subclass)";
+ weaken($self->{'$!associated_class'} = $class);
+}
+
+sub detach_from_class {
+ my $self = shift;
+ $self->{'$!associated_class'} = undef;
+}
+
+# method association
+
+sub associate_method {
+ my ($self, $method) = @_;
+ push @{$self->{'@!associated_methods'}} => $method;
+}
+
+## Slot management
+
+sub set_value {
+ my ($self, $instance, $value) = @_;
+
+ Class::MOP::Class->initialize(blessed($instance))
+ ->get_meta_instance
+ ->set_slot_value($instance, $self->name, $value);
+}
+
+sub get_value {
+ my ($self, $instance) = @_;
+
+ Class::MOP::Class->initialize(blessed($instance))
+ ->get_meta_instance
+ ->get_slot_value($instance, $self->name);
+}
+
+sub has_value {
+ my ($self, $instance) = @_;
+
+ defined Class::MOP::Class->initialize(blessed($instance))
+ ->get_meta_instance
+ ->get_slot_value($instance, $self->name) ? 1 : 0;
+}
+
+sub clear_value {
+ my ($self, $instance) = @_;
- if ($self->has_accessor()) {
- my $method = $class->get_method($self->accessor);
- $class->remove_method($self->accessor)
- if (blessed($method) && $method->isa('Class::MOP::Attribute::Accessor'));
+ Class::MOP::Class->initialize(blessed($instance))
+ ->get_meta_instance
+ ->deinitialize_slot($instance, $self->name);
+}
+
+## load em up ...
+
+sub accessor_metaclass { 'Class::MOP::Method::Accessor' }
+
+sub process_accessors {
+ my ($self, $type, $accessor, $generate_as_inline_methods) = @_;
+ if (reftype($accessor)) {
+ (reftype($accessor) eq 'HASH')
+ || confess "bad accessor/reader/writer/predicate/clearer format, must be a HASH ref";
+ my ($name, $method) = %{$accessor};
+ $method = $self->accessor_metaclass->wrap($method);
+ $self->associate_method($method);
+ return ($name, $method);
}
else {
- if ($self->has_reader()) {
- my $method = $class->get_method($self->reader);
- $class->remove_method($self->reader)
- if (blessed($method) && $method->isa('Class::MOP::Attribute::Accessor'));
- }
- if ($self->has_writer()) {
- my $method = $class->get_method($self->writer);
- $class->remove_method($self->writer)
- if (blessed($method) && $method->isa('Class::MOP::Attribute::Accessor'));
- }
- }
+ my $inline_me = ($generate_as_inline_methods && $self->associated_class->instance_metaclass->is_inlinable);
+ my $method;
+ eval {
+ $method = $self->accessor_metaclass->new(
+ attribute => $self,
+ is_inline => $inline_me,
+ accessor_type => $type,
+ );
+ };
+ confess "Could not create the '$type' method for " . $self->name . " because : $@" if $@;
+ $self->associate_method($method);
+ return ($accessor, $method);
+ }
}
-package Class::MOP::Attribute::Accessor;
-
-use strict;
-use warnings;
+sub install_accessors {
+ my $self = shift;
+ my $inline = shift;
+ my $class = $self->associated_class;
+
+ $class->add_method(
+ $self->process_accessors('accessor' => $self->accessor(), $inline)
+ ) if $self->has_accessor();
+
+ $class->add_method(
+ $self->process_accessors('reader' => $self->reader(), $inline)
+ ) if $self->has_reader();
+
+ $class->add_method(
+ $self->process_accessors('writer' => $self->writer(), $inline)
+ ) if $self->has_writer();
+
+ $class->add_method(
+ $self->process_accessors('predicate' => $self->predicate(), $inline)
+ ) if $self->has_predicate();
+
+ $class->add_method(
+ $self->process_accessors('clearer' => $self->clearer(), $inline)
+ ) if $self->has_clearer();
+
+ return;
+}
-our $VERSION = '0.01';
+{
+ my $_remove_accessor = sub {
+ my ($accessor, $class) = @_;
+ if (reftype($accessor) && reftype($accessor) eq 'HASH') {
+ ($accessor) = keys %{$accessor};
+ }
+ my $method = $class->get_method($accessor);
+ $class->remove_method($accessor)
+ if (blessed($method) && $method->isa('Class::MOP::Method::Accessor'));
+ };
+
+ sub remove_accessors {
+ my $self = shift;
+ # TODO:
+ # we really need to make sure to remove from the
+ # associates methods here as well. But this is
+ # such a slimly used method, I am not worried
+ # about it right now.
+ $_remove_accessor->($self->accessor(), $self->associated_class()) if $self->has_accessor();
+ $_remove_accessor->($self->reader(), $self->associated_class()) if $self->has_reader();
+ $_remove_accessor->($self->writer(), $self->associated_class()) if $self->has_writer();
+ $_remove_accessor->($self->predicate(), $self->associated_class()) if $self->has_predicate();
+ $_remove_accessor->($self->clearer(), $self->associated_class()) if $self->has_clearer();
+ return;
+ }
-our @ISA = ('Class::MOP::Method');
+}
1;
=head1 SYNOPSIS
Class::MOP::Attribute->new('$foo' => (
- accessor => 'foo', # dual purpose get/set accessor
- init_arg => '-foo', # class->new will look for a -foo key
- default => 'BAR IS BAZ!' # if no -foo key is provided, use this
+ accessor => 'foo', # dual purpose get/set accessor
+ predicate => 'has_foo' # predicate check for defined-ness
+ init_arg => '-foo', # class->new will look for a -foo key
+ default => 'BAR IS BAZ!' # if no -foo key is provided, use this
));
Class::MOP::Attribute->new('$.bar' => (
- reader => 'bar', # getter
- writer => 'set_bar', # setter
- init_arg => '-bar', # class->new will look for a -bar key
+ reader => 'bar', # getter
+ writer => 'set_bar', # setter
+ predicate => 'has_bar' # predicate check for defined-ness
+ init_arg => ':bar', # class->new will look for a :bar key
# no default value means it is undef
));
=head1 DESCRIPTION
-The Attribute Protocol is almost entirely an invention of this module. This is
-because Perl 5 does not have consistent notion of what is an attribute
-of a class. There are so many ways in which this is done, and very few
-(if any) are discoverable by this module.
+The Attribute Protocol is almost entirely an invention of this module,
+and is completely optional to this MOP. This is because Perl 5 does not
+have consistent notion of what is an attribute of a class. There are
+so many ways in which this is done, and very few (if any) are
+easily discoverable by this module.
So, all that said, this module attempts to inject some order into this
-chaos, by introducing a more consistent approach.
+chaos, by introducing a consistent API which can be used to create
+object attributes.
=head1 METHODS
=over 4
-=item B<new ($name, %accessor_description, $class_initialization_arg, $default_value)>
+=item B<new ($name, ?%options)>
+
+An attribute must (at the very least), have a C<$name>. All other
+C<%options> are contained added as key-value pairs. Acceptable keys
+are as follows:
+
+=over 4
+
+=item I<init_arg>
+
+This should be a string value representing the expected key in
+an initialization hash. For instance, if we have an I<init_arg>
+value of C<-foo>, then the following code will Just Work.
+
+ MyClass->meta->construct_instance(-foo => "Hello There");
+
+In an init_arg is not assigned, it will automatically use the
+value of C<$name>.
+
+=item I<default>
+
+The value of this key is the default value which
+C<Class::MOP::Class::construct_instance> will initialize the
+attribute to.
+
+B<NOTE:>
+If the value is a simple scalar (string or number), then it can
+be just passed as is. However, if you wish to initialize it with
+a HASH or ARRAY ref, then you need to wrap that inside a CODE
+reference, like so:
+
+ Class::MOP::Attribute->new('@foo' => (
+ default => sub { [] },
+ ));
+
+ # or ...
+
+ Class::MOP::Attribute->new('%foo' => (
+ default => sub { {} },
+ ));
+
+If you wish to initialize an attribute with a CODE reference
+itself, then you need to wrap that in a subroutine as well, like
+so:
+
+ Class::MOP::Attribute->new('&foo' => (
+ default => sub { sub { print "Hello World" } },
+ ));
+
+And lastly, if the value of your attribute is dependent upon
+some other aspect of the instance structure, then you can take
+advantage of the fact that when the I<default> value is a CODE
+reference, it is passed the raw (unblessed) instance structure
+as it's only argument. So you can do things like this:
+
+ Class::MOP::Attribute->new('$object_identity' => (
+ default => sub { Scalar::Util::refaddr($_[0]) },
+ ));
+
+This last feature is fairly limited as there is no gurantee of
+the order of attribute initializations, so you cannot perform
+any kind of dependent initializations. However, if this is
+something you need, you could subclass B<Class::MOP::Class> and
+this class to acheive it. However, this is currently left as
+an exercise to the reader :).
+
+=back
+
+The I<accessor>, I<reader>, I<writer>, I<predicate> and I<clearer> keys can
+contain either; the name of the method and an appropriate default one will be
+generated for you, B<or> a HASH ref containing exactly one key (which will be
+used as the name of the method) and one value, which should contain a CODE
+reference which will be installed as the method itself.
+
+=over 4
+
+=item I<accessor>
+
+The I<accessor> is a standard perl-style read/write accessor. It will
+return the value of the attribute, and if a value is passed as an argument,
+it will assign that value to the attribute.
+
+B<NOTE:>
+This method will properly handle the following code, by assigning an
+C<undef> value to the attribute.
+
+ $object->set_something(undef);
+
+=item I<reader>
+
+This is a basic read-only accessor, it will just return the value of
+the attribute.
+
+=item I<writer>
+
+This is a basic write accessor, it accepts a single argument, and
+assigns that value to the attribute. This method does not intentially
+return a value, however perl will return the result of the last
+expression in the subroutine, which returns in this returning the
+same value that it was passed.
+
+B<NOTE:>
+This method will properly handle the following code, by assigning an
+C<undef> value to the attribute.
+
+ $object->set_something();
+
+=item I<predicate>
+
+This is a basic test to see if the value of the attribute is not
+C<undef>. It will return true (C<1>) if the attribute's value is
+defined, and false (C<0>) otherwise.
+
+=item I<clearer>
+
+This is the a method that will uninitialize the attr, reverting lazy values
+back to their "unfulfilled" state.
+
+=back
+
+=item B<clone (%options)>
+
+=item B<initialize_instance_slot ($instance, $params)>
=back
+=head2 Value management
+
+These methods are basically "backdoors" to the instance, which can be used
+to bypass the regular accessors, but still stay within the context of the MOP.
+
+These methods are not for general use, and should only be used if you really
+know what you are doing.
+
+=over 4
+
+=item B<set_value ($instance, $value)>
+
+Set the value without going through the accessor. Note that this may be done to
+even attributes with just read only accessors.
+
+=item B<get_value ($instance)>
+
+Return the value without going through the accessor. Note that this may be done
+even to attributes with just write only accessors.
+
+=item B<has_value ($instance)>
+
+Returns a boolean indicating if the item in the C<$instance> has a value in it.
+This is basically what the default C<predicate> method calls.
+
+=item B<clear_value ($instance)>
+
+This will clear the value in the C<$instance>. This is basically what the default
+C<clearer> would call. Note that this may be done even if the attirbute does not
+have any associated read, write or clear methods.
+
+=back
+
=head2 Informational
+These are all basic read-only value accessors for the values
+passed into C<new>. I think they are pretty much self-explanitory.
+
=over 4
=item B<name>
=item B<writer>
+=item B<predicate>
+
+=item B<clearer>
+
=item B<init_arg>
-=item B<default>
+=item B<is_default_a_coderef>
+
+=item B<default (?$instance)>
+
+As noted in the documentation for C<new> above, if the I<default>
+value is a CODE reference, this accessor will pass a single additional
+argument C<$instance> into it and return the value.
+
+=item B<slots>
+
+Returns a list of slots required by the attribute. This is usually
+just one, which is the name of the attribute.
+
+=item B<get_read_method>
+
+=item B<get_write_method>
+
+Return the name of a method suitable for reading / writing the value of the
+attribute in the associated class. Suitable for use whether C<reader> and
+C<writer> or C<accessor> was used.
=back
=head2 Informational predicates
+These are all basic predicate methods for the values passed into C<new>.
+
=over 4
=item B<has_accessor>
-Returns true if this attribute uses a get/set accessor, and false
-otherwise
-
=item B<has_reader>
-Returns true if this attribute has a reader, and false otherwise
-
=item B<has_writer>
-Returns true if this attribute has a writer, and false otherwise
+=item B<has_predicate>
-=item B<has_init_arg>
+=item B<has_clearer>
-Returns true if this attribute has a class intialization argument, and
-false otherwise
+=item B<has_init_arg>
=item B<has_default>
-Returns true if this attribute has a default value, and false
-otherwise.
+=back
+
+=head2 Class association
+
+These methods allow you to manage the attributes association with
+the class that contains it. These methods should not be used
+lightly, nor are they very magical, they are mostly used internally
+and by metaclass instances.
+
+=over 4
+
+=item B<associated_class>
+
+This returns the metaclass this attribute is associated with.
+
+=item B<attach_to_class ($class)>
+
+This will store a weaken reference to C<$class> internally. You should
+note that just changing the class assocation will not remove the attribute
+from it's old class, and initialize it (and it's accessors) in the new
+C<$class>. It is up to you to do this manually.
+
+=item B<detach_from_class>
+
+This will remove the weakened reference to the class. It does B<not>
+remove the attribute itself from the class (or remove it's accessors),
+you must do that yourself if you want too. Actually if that is what
+you want to do, you should probably be looking at
+L<Class::MOP::Class::remove_attribute> instead.
=back
=over 4
-=item B<install_accessors ($class)>
+=item B<accessor_metaclass>
+
+Accessors are generated by an accessor metaclass, which is usually
+a subclass of C<Class::MOP::Method::Accessor>. This method returns
+the name of the accessor metaclass that this attribute uses.
+
+=item B<associate_method ($method)>
+
+This will associate a C<$method> with the given attribute which is
+used internally by the accessor generator.
+
+=item B<associated_methods>
+
+This will return the list of methods which have been associated with
+the C<associate_method> methods.
+
+=item B<install_accessors>
This allows the attribute to generate and install code for it's own
-accessor methods. This is called by C<Class::MOP::Class::add_attribute>.
+I<accessor/reader/writer/predicate> methods. This is called by
+C<Class::MOP::Class::add_attribute>.
-=item B<remove_accessors ($class)>
+This method will call C<process_accessors> for each of the possible
+method types (accessor, reader, writer & predicate).
+
+=item B<process_accessors ($type, $value)>
+
+This takes a C<$type> (accessor, reader, writer or predicate), and
+a C<$value> (the value passed into the constructor for each of the
+different types). It will then either generate the method itself
+(using the C<generate_*_method> methods listed below) or it will
+use the custom method passed through the constructor.
+
+=item B<remove_accessors>
This allows the attribute to remove the method for it's own
-accessor. This is called by C<Class::MOP::Class::remove_attribute>.
+I<accessor/reader/writer/predicate/clearer>. This is called by
+C<Class::MOP::Class::remove_attribute>.
+
+NOTE: This does not currently remove methods from the list returned
+by C<associated_methods>, that is on the TODO list.
=back
=item B<meta>
+This will return a B<Class::MOP::Class> instance which is related
+to this class.
+
+It should also be noted that B<Class::MOP> will actually bootstrap
+this module by installing a number of attribute meta-objects into
+it's metaclass. This will allow this class to reap all the benifits
+of the MOP when subclassing it.
+
=back
-=head1 AUTHOR
+=head1 AUTHORS
+
+Stevan Little E<lt>stevan@iinteractive.comE<gt>
-Stevan Little E<gt>stevan@iinteractive.comE<lt>
+Yuval Kogman E<lt>nothingmuch@woobling.comE<gt>
=head1 COPYRIGHT AND LICENSE
-Copyright 2006 by Infinity Interactive, Inc.
+Copyright 2006, 2007 by Infinity Interactive, Inc.
L<http://www.iinteractive.com>
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
-=cut
\ No newline at end of file
+=cut
+
+
projects / gitmo/Class-MOP.git / blobdiff