--- /dev/null
+
+package Class::MOP::Instance;
+
+use strict;
+use warnings;
+
+use Scalar::Util 'weaken', 'blessed';
+
+our $VERSION = '0.95';
+$VERSION = eval $VERSION;
+our $AUTHORITY = 'cpan:STEVAN';
+
+use base 'Class::MOP::Object';
+
+sub BUILDARGS {
+ my ($class, @args) = @_;
+
+ if ( @args == 1 ) {
+ unshift @args, "associated_metaclass";
+ } elsif ( @args >= 2 && blessed($args[0]) && $args[0]->isa("Class::MOP::Class") ) {
+ # compat mode
+ my ( $meta, @attrs ) = @args;
+ @args = ( associated_metaclass => $meta, attributes => \@attrs );
+ }
+
+ my %options = @args;
+ # FIXME lazy_build
+ $options{slots} ||= [ map { $_->slots } @{ $options{attributes} || [] } ];
+ $options{slot_hash} = { map { $_ => undef } @{ $options{slots} } }; # FIXME lazy_build
+
+ return \%options;
+}
+
+sub new {
+ my $class = shift;
+ my $options = $class->BUILDARGS(@_);
+
+ # FIXME replace with a proper constructor
+ my $instance = $class->_new(%$options);
+
+ # FIXME weak_ref => 1,
+ weaken($instance->{'associated_metaclass'});
+
+ return $instance;
+}
+
+sub _new {
+ my $class = shift;
+ return Class::MOP::Class->initialize($class)->new_object(@_)
+ if $class ne __PACKAGE__;
+
+ my $params = @_ == 1 ? $_[0] : {@_};
+ return bless {
+ # NOTE:
+ # I am not sure that it makes
+ # sense to pass in the meta
+ # The ideal would be to just
+ # pass in the class name, but
+ # that is placing too much of
+ # an assumption on bless(),
+ # which is *probably* a safe
+ # assumption,.. but you can
+ # never tell <:)
+ 'associated_metaclass' => $params->{associated_metaclass},
+ 'attributes' => $params->{attributes},
+ 'slots' => $params->{slots},
+ 'slot_hash' => $params->{slot_hash},
+ } => $class;
+}
+
+sub _class_name { $_[0]->{_class_name} ||= $_[0]->associated_metaclass->name }
+
+sub associated_metaclass { $_[0]{'associated_metaclass'} }
+
+sub create_instance {
+ my $self = shift;
+ bless {}, $self->_class_name;
+}
+
+sub clone_instance {
+ my ($self, $instance) = @_;
+ bless { %$instance }, $self->_class_name;
+}
+
+# operations on meta instance
+
+sub get_all_slots {
+ my $self = shift;
+ return @{$self->{'slots'}};
+}
+
+sub get_all_attributes {
+ my $self = shift;
+ return @{$self->{attributes}};
+}
+
+sub is_valid_slot {
+ my ($self, $slot_name) = @_;
+ exists $self->{'slot_hash'}->{$slot_name};
+}
+
+# operations on created instances
+
+sub get_slot_value {
+ my ($self, $instance, $slot_name) = @_;
+ $instance->{$slot_name};
+}
+
+sub set_slot_value {
+ my ($self, $instance, $slot_name, $value) = @_;
+ $instance->{$slot_name} = $value;
+}
+
+sub initialize_slot {
+ my ($self, $instance, $slot_name) = @_;
+ return;
+}
+
+sub deinitialize_slot {
+ my ( $self, $instance, $slot_name ) = @_;
+ delete $instance->{$slot_name};
+}
+
+sub initialize_all_slots {
+ my ($self, $instance) = @_;
+ foreach my $slot_name ($self->get_all_slots) {
+ $self->initialize_slot($instance, $slot_name);
+ }
+}
+
+sub deinitialize_all_slots {
+ my ($self, $instance) = @_;
+ foreach my $slot_name ($self->get_all_slots) {
+ $self->deinitialize_slot($instance, $slot_name);
+ }
+}
+
+sub is_slot_initialized {
+ my ($self, $instance, $slot_name, $value) = @_;
+ exists $instance->{$slot_name};
+}
+
+sub weaken_slot_value {
+ my ($self, $instance, $slot_name) = @_;
+ weaken $instance->{$slot_name};
+}
+
+sub strengthen_slot_value {
+ my ($self, $instance, $slot_name) = @_;
+ $self->set_slot_value($instance, $slot_name, $self->get_slot_value($instance, $slot_name));
+}
+
+sub rebless_instance_structure {
+ my ($self, $instance, $metaclass) = @_;
+
+ # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
+ bless $_[1], $metaclass->name;
+}
+
+sub is_dependent_on_superclasses {
+ return; # for meta instances that require updates on inherited slot changes
+}
+
+# inlinable operation snippets
+
+sub is_inlinable { 1 }
+
+sub inline_create_instance {
+ my ($self, $class_variable) = @_;
+ 'bless {} => ' . $class_variable;
+}
+
+sub inline_slot_access {
+ my ($self, $instance, $slot_name) = @_;
+ sprintf q[%s->{"%s"}], $instance, quotemeta($slot_name);
+}
+
+sub inline_get_slot_value {
+ my ($self, $instance, $slot_name) = @_;
+ $self->inline_slot_access($instance, $slot_name);
+}
+
+sub inline_set_slot_value {
+ my ($self, $instance, $slot_name, $value) = @_;
+ $self->inline_slot_access($instance, $slot_name) . " = $value",
+}
+
+sub inline_initialize_slot {
+ my ($self, $instance, $slot_name) = @_;
+ return '';
+}
+
+sub inline_deinitialize_slot {
+ my ($self, $instance, $slot_name) = @_;
+ "delete " . $self->inline_slot_access($instance, $slot_name);
+}
+sub inline_is_slot_initialized {
+ my ($self, $instance, $slot_name) = @_;
+ "exists " . $self->inline_slot_access($instance, $slot_name);
+}
+
+sub inline_weaken_slot_value {
+ my ($self, $instance, $slot_name) = @_;
+ sprintf "Scalar::Util::weaken( %s )", $self->inline_slot_access($instance, $slot_name);
+}
+
+sub inline_strengthen_slot_value {
+ my ($self, $instance, $slot_name) = @_;
+ $self->inline_set_slot_value($instance, $slot_name, $self->inline_slot_access($instance, $slot_name));
+}
+
+sub inline_rebless_instance_structure {
+ my ($self, $instance, $class_variable) = @_;
+ "bless $instance => $class_variable";
+}
+
+1;
+
+__END__
+
+=pod
+
+=head1 NAME
+
+Class::MOP::Instance - Instance Meta Object
+
+=head1 DESCRIPTION
+
+The Instance Protocol controls the creation of object instances, and
+the storage of attribute values in those instances.
+
+Using this API directly in your own code violates encapsulation, and
+we recommend that you use the appropriate APIs in L<Class::MOP::Class>
+and L<Class::MOP::Attribute> instead. Those APIs in turn call the
+methods in this class as appropriate.
+
+This class also participates in generating inlined code by providing
+snippets of code to access an object instance.
+
+=head1 METHODS
+
+=head2 Object construction
+
+=over 4
+
+=item B<< Class::MOP::Instance->new(%options) >>
+
+This method creates a new meta-instance object.
+
+It accepts the following keys in C<%options>:
+
+=over 8
+
+=item * associated_metaclass
+
+The L<Class::MOP::Class> object for which instances will be created.
+
+=item * attributes
+
+An array reference of L<Class::MOP::Attribute> objects. These are the
+attributes which can be stored in each instance.
+
+=back
+
+=back
+
+=head2 Creating and altering instances
+
+=over 4
+
+=item B<< $metainstance->create_instance >>
+
+This method returns a reference blessed into the associated
+metaclass's class.
+
+The default is to use a hash reference. Subclasses can override this.
+
+=item B<< $metainstance->clone_instance($instance) >>
+
+Given an instance, this method creates a new object by making
+I<shallow> clone of the original.
+
+=back
+
+=head2 Introspection
+
+=over 4
+
+=item B<< $metainstance->associated_metaclass >>
+
+This returns the L<Class::MOP::Class> object associated with the
+meta-instance object.
+
+=item B<< $metainstance->get_all_slots >>
+
+This returns a list of slot names stored in object instances. In
+almost all cases, slot names correspond directly attribute names.
+
+=item B<< $metainstance->is_valid_slot($slot_name) >>
+
+This will return true if C<$slot_name> is a valid slot name.
+
+=item B<< $metainstance->get_all_attributes >>
+
+This returns a list of attributes corresponding to the attributes
+passed to the constructor.
+
+=back
+
+=head2 Operations on Instance Structures
+
+It's important to understand that the meta-instance object is a
+different entity from the actual instances it creates. For this
+reason, any operations on the C<$instance_structure> always require
+that the object instance be passed to the method.
+
+=over 4
+
+=item B<< $metainstance->get_slot_value($instance_structure, $slot_name) >>
+
+=item B<< $metainstance->set_slot_value($instance_structure, $slot_name, $value) >>
+
+=item B<< $metainstance->initialize_slot($instance_structure, $slot_name) >>
+
+=item B<< $metainstance->deinitialize_slot($instance_structure, $slot_name) >>
+
+=item B<< $metainstance->initialize_all_slots($instance_structure) >>
+
+=item B<< $metainstance->deinitialize_all_slots($instance_structure) >>
+
+=item B<< $metainstance->is_slot_initialized($instance_structure, $slot_name) >>
+
+=item B<< $metainstance->weaken_slot_value($instance_structure, $slot_name) >>
+
+=item B<< $metainstance->strengthen_slot_value($instance_structure, $slot_name) >>
+
+=item B<< $metainstance->rebless_instance_structure($instance_structure, $new_metaclass) >>
+
+The exact details of what each method does should be fairly obvious
+from the method name.
+
+=back
+
+=head2 Inlinable Instance Operations
+
+=over 4
+
+=item B<< $metainstance->is_inlinable >>
+
+This is a boolean that indicates whether or not slot access operations
+can be inlined. By default it is true, but subclasses can override
+this.
+
+=item B<< $metainstance->inline_create_instance($class_variable) >>
+
+This method expects a string that, I<when inlined>, will become a
+class name. This would literally be something like C<'$class'>, not an
+actual class name.
+
+It returns a snippet of code that creates a new object for the
+class. This is something like C< bless {}, $class_name >.
+
+=item B<< $metainstance->inline_slot_access($instance_variable, $slot_name) >>
+
+=item B<< $metainstance->inline_get_slot_value($instance_variable, $slot_name) >>
+
+=item B<< $metainstance->inline_set_slot_value($instance_variable, $slot_name, $value) >>
+
+=item B<< $metainstance->inline_initialize_slot($instance_variable, $slot_name) >>
+
+=item B<< $metainstance->inline_deinitialize_slot($instance_variable, $slot_name) >>
+
+=item B<< $metainstance->inline_is_slot_initialized($instance_variable, $slot_name) >>
+
+=item B<< $metainstance->inline_weaken_slot_value($instance_variable, $slot_name) >>
+
+=item B<< $metainstance->inline_strengthen_slot_value($instance_variable, $slot_name) >>
+
+These methods all expect two arguments. The first is the name of a
+variable, than when inlined, will represent the object
+instance. Typically this will be a literal string like C<'$_[0]'>.
+
+The second argument is a slot name.
+
+The method returns a snippet of code that, when inlined, performs some
+operation on the instance.
+
+=item B<< $metainstance->inline_rebless_instance_structure($instance_variable, $class_variable) >>
+
+This takes the name of a variable that will, when inlined, represent the object
+instance, and the name of a variable that will represent the class to rebless
+into, and returns code to rebless an instance into a class.
+
+=back
+
+=head2 Introspection
+
+=over 4
+
+=item B<< Class::MOP::Instance->meta >>
+
+This will return a L<Class::MOP::Class> instance for this class.
+
+It should also be noted that L<Class::MOP> will actually bootstrap
+this module by installing a number of attribute meta-objects into its
+metaclass.
+
+=back
+
+=head1 AUTHORS
+
+Yuval Kogman E<lt>nothingmuch@woobling.comE<gt>
+
+Stevan Little E<lt>stevan@iinteractive.comE<gt>
+
+=head1 COPYRIGHT AND LICENSE
+
+Copyright 2006-2009 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
+
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