1Class::MOP::Instance(3)User Contributed Perl DocumentatioCnlass::MOP::Instance(3)
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6 Class::MOP::Instance - Instance Meta Object
7
9 version 2.2014
10
12 The Instance Protocol controls the creation of object instances, and
13 the storage of attribute values in those instances.
14 Using this API directly in your own code violates encapsulation, and we
16 recommend that you use the appropriate APIs in Class::MOP::Class and
17 Class::MOP::Attribute instead. Those APIs in turn call the methods in
18 this class as appropriate.
19 This class also participates in generating inlined code by providing
21 snippets of code to access an object instance.
22
24 Object construction
25 Class::MOP::Instance->new(%options)
26 This method creates a new meta-instance object.
27 It accepts the following keys in %options:
29 • associated_metaclass
31 The Class::MOP::Class object for which instances will be
33 created.
34 • attributes
36 An array reference of Class::MOP::Attribute objects. These
38 are the attributes which can be stored in each instance.
39 Creating and altering instances
41 $metainstance->create_instance
42 This method returns a reference blessed into the associated
43 metaclass's class.
44 The default is to use a hash reference. Subclasses can override
46 this.
47 $metainstance->clone_instance($instance)
49 Given an instance, this method creates a new object by making
50 shallow clone of the original.
51 Introspection
53 $metainstance->associated_metaclass
54 This returns the Class::MOP::Class object associated with the meta-
55 instance object.
56 $metainstance->get_all_slots
58 This returns a list of slot names stored in object instances. In
59 almost all cases, slot names correspond directly attribute names.
60 $metainstance->is_valid_slot($slot_name)
62 This will return true if $slot_name is a valid slot name.
63 $metainstance->get_all_attributes
65 This returns a list of attributes corresponding to the attributes
66 passed to the constructor.
67 Operations on Instance Structures
69 It's important to understand that the meta-instance object is a
70 different entity from the actual instances it creates. For this reason,
71 any operations on the $instance_structure always require that the
72 object instance be passed to the method.
73 $metainstance->get_slot_value($instance_structure, $slot_name)
75 $metainstance->set_slot_value($instance_structure, $slot_name, $value)
76 $metainstance->initialize_slot($instance_structure, $slot_name)
77 $metainstance->deinitialize_slot($instance_structure, $slot_name)
78 $metainstance->initialize_all_slots($instance_structure)
79 $metainstance->deinitialize_all_slots($instance_structure)
80 $metainstance->is_slot_initialized($instance_structure, $slot_name)
81 $metainstance->weaken_slot_value($instance_structure, $slot_name)
82 $metainstance->slot_value_is_weak($instance_structure, $slot_name)
83 $metainstance->strengthen_slot_value($instance_structure, $slot_name)
84 $metainstance->rebless_instance_structure($instance_structure,
85 $new_metaclass)
86 The exact details of what each method does should be fairly obvious
87 from the method name.
88 Inlinable Instance Operations
90 $metainstance->is_inlinable
91 This is a boolean that indicates whether or not slot access
92 operations can be inlined. By default it is true, but subclasses
93 can override this.
94 $metainstance->inline_create_instance($class_variable)
96 This method expects a string that, when inlined, will become a
97 class name. This would literally be something like '$class', not an
98 actual class name.
99 It returns a snippet of code that creates a new object for the
101 class. This is something like " bless {}, $class_name ".
102 $metainstance->inline_get_is_lvalue
104 Returns whether or not "inline_get_slot_value" is a valid lvalue.
105 This can be used to do extra optimizations when generating inlined
106 methods.
107 $metainstance->inline_slot_access($instance_variable, $slot_name)
109 $metainstance->inline_get_slot_value($instance_variable, $slot_name)
110 $metainstance->inline_set_slot_value($instance_variable, $slot_name,
111 $value)
112 $metainstance->inline_initialize_slot($instance_variable, $slot_name)
113 $metainstance->inline_deinitialize_slot($instance_variable, $slot_name)
114 $metainstance->inline_is_slot_initialized($instance_variable,
115 $slot_name)
116 $metainstance->inline_weaken_slot_value($instance_variable, $slot_name)
117 $metainstance->inline_strengthen_slot_value($instance_variable,
118 $slot_name)
119 These methods all expect two arguments. The first is the name of a
120 variable, than when inlined, will represent the object instance.
121 Typically this will be a literal string like '$_[0]'.
122 The second argument is a slot name.
124 The method returns a snippet of code that, when inlined, performs
126 some operation on the instance.
127 $metainstance->inline_rebless_instance_structure($instance_variable,
129 $class_variable)
130 This takes the name of a variable that will, when inlined,
131 represent the object instance, and the name of a variable that will
132 represent the class to rebless into, and returns code to rebless an
133 instance into a class.
134 Introspection
136 Class::MOP::Instance->meta
137 This will return a Class::MOP::Class instance for this class.
138 It should also be noted that Class::MOP will actually bootstrap
140 this module by installing a number of attribute meta-objects into
141 its metaclass.
142
144 • Stevan Little <stevan@cpan.org>
145 • Dave Rolsky <autarch@urth.org>
147 • Jesse Luehrs <doy@cpan.org>
149 • Shawn M Moore <sartak@cpan.org>
151 • יובל קוג'מן (Yuval Kogman) <nothingmuch@woobling.org>
153 • Karen Etheridge <ether@cpan.org>
155 • Florian Ragwitz <rafl@debian.org>
157 • Hans Dieter Pearcey <hdp@cpan.org>
159 • Chris Prather <chris@prather.org>
161 • Matt S Trout <mstrout@cpan.org>
163
165 This software is copyright (c) 2006 by Infinity Interactive, Inc.
166 This is free software; you can redistribute it and/or modify it under
168 the same terms as the Perl 5 programming language system itself.
169perl v5.32.1 2021-01-27 Class::MOP::Instance(3)