Object construction

Class::MOP::Instance->new(%options)

This method creates a new meta-instance object.

It accepts the following keys in %options:

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.