phpman > perldoc > Class::MOP::Instance(3pm)

NAME
    Class::MOP::Instance - Instance Meta Object

VERSION
    version 2.2200

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 Class::MOP::Class and 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.

METHODS
  Object construction
    Class::MOP::Instance->new(%options)
        This method creates a new meta-instance object.

        It accepts the following keys in %options:

        *       associated_metaclass

                The Class::MOP::Class object for which instances will be created.

        *       attributes

                An array reference of Class::MOP::Attribute objects. These are the attributes which
                can be stored in each instance.

  Creating and altering instances
    $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.

    $metainstance->clone_instance($instance)
        Given an instance, this method creates a new object by making *shallow* clone of the
        original.

  Introspection
    $metainstance->associated_metaclass
        This returns the Class::MOP::Class object associated with the meta-instance object.

    $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.

    $metainstance->is_valid_slot($slot_name)
        This will return true if $slot_name is a valid slot name.

    $metainstance->get_all_attributes
        This returns a list of attributes corresponding to the attributes passed to the constructor.

  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 $instance_structure always require
    that the object instance be passed to the method.

    $metainstance->get_slot_value($instance_structure, $slot_name)
    $metainstance->set_slot_value($instance_structure, $slot_name, $value)
    $metainstance->initialize_slot($instance_structure, $slot_name)
    $metainstance->deinitialize_slot($instance_structure, $slot_name)
    $metainstance->initialize_all_slots($instance_structure)
    $metainstance->deinitialize_all_slots($instance_structure)
    $metainstance->is_slot_initialized($instance_structure, $slot_name)
    $metainstance->weaken_slot_value($instance_structure, $slot_name)
    $metainstance->slot_value_is_weak($instance_structure, $slot_name)
    $metainstance->strengthen_slot_value($instance_structure, $slot_name)
    $metainstance->rebless_instance_structure($instance_structure, $new_metaclass)
        The exact details of what each method does should be fairly obvious from the method name.

  Inlinable Instance Operations
    $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.

    $metainstance->inline_create_instance($class_variable)
        This method expects a string that, *when inlined*, will become a class name. This would
        literally be something like '$class', not an actual class name.

        It returns a snippet of code that creates a new object for the class. This is something like
        " bless {}, $class_name ".

    $metainstance->inline_get_is_lvalue
        Returns whether or not "inline_get_slot_value" is a valid lvalue. This can be used to do
        extra optimizations when generating inlined methods.

    $metainstance->inline_slot_access($instance_variable, $slot_name)
    $metainstance->inline_get_slot_value($instance_variable, $slot_name)
    $metainstance->inline_set_slot_value($instance_variable, $slot_name, $value)
    $metainstance->inline_initialize_slot($instance_variable, $slot_name)
    $metainstance->inline_deinitialize_slot($instance_variable, $slot_name)
    $metainstance->inline_is_slot_initialized($instance_variable, $slot_name)
    $metainstance->inline_weaken_slot_value($instance_variable, $slot_name)
    $metainstance->inline_strengthen_slot_value($instance_variable, $slot_name)
        These methods all expect two arguments. The first is the name of a variable, than when
        inlined, will represent the object instance. Typically this will be a literal string like
        '$_[0]'.

        The second argument is a slot name.

        The method returns a snippet of code that, when inlined, performs some operation on the
        instance.

    $metainstance->inline_rebless_instance_structure($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.

  Introspection
    Class::MOP::Instance->meta
        This will return a Class::MOP::Class instance for this class.

        It should also be noted that Class::MOP will actually bootstrap this module by installing a
        number of attribute meta-objects into its metaclass.

AUTHORS
    *   Stevan Little <stevan AT cpan.org>

    *   Dave Rolsky <autarch AT urth.org>

    *   Jesse Luehrs <doy AT cpan.org>

    *   Shawn M Moore <sartak AT cpan.org>

    *   יובל קוג'מן (Yuval Kogman) <nothingmuch AT woobling.org>

    *   Karen Etheridge <ether AT cpan.org>

    *   Florian Ragwitz <rafl AT debian.org>

    *   Hans Dieter Pearcey <hdp AT cpan.org>

    *   Chris Prather <chris AT prather.org>

    *   Matt S Trout <mstrout AT cpan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2006 by Infinity Interactive, Inc.

    This is free software; you can redistribute it and/or modify it under the same terms as the Perl
    5 programming language system itself.