NAME¶
Class::MOP::Instance - Instance Meta Object
VERSION¶
version 2.1213
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.little@iinteractive.com>
- •
- Dave Rolsky <autarch@urth.org>
- •
- Jesse Luehrs <doy@tozt.net>
- •
- Shawn M Moore <code@sartak.org>
- •
- XXXX XXX'XX (Yuval Kogman) <nothingmuch@woobling.org>
- •
- Karen Etheridge <ether@cpan.org>
- •
- Florian Ragwitz <rafl@debian.org>
- •
- Hans Dieter Pearcey <hdp@weftsoar.net>
- •
- Chris Prather <chris@prather.org>
- •
- Matt S Trout <mst@shadowcat.co.uk>
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.