17 Class::MOP - A Meta Object Protocol for Perl 5
25 This module is an attempt to create a meta object protocol for the
26 Perl 5 object system. It makes no attempt to change the behavior or
27 characteristics of the Perl 5 object system, only to create a
28 protocol for it's manipulation and introspection.
30 That said, it does attempt to create the tools for building a rich
31 set of extensions to the Perl 5 object system. Every attempt has been
32 made for these tools to keep to the spirit of the Perl 5 object
33 system that we all know and love.
35 =head2 Who is this module for?
37 This module is specifically for anyone who has ever created or
38 wanted to create a module for the Class:: namespace. The tools which
39 this module will provide will hopefully make it easier to do more
40 complex things with Perl 5 classes by removing such barriers as
41 the need to hack the symbol tables, or understand the fine details
46 The protocol is divided into 3 main sub-protocols:
50 =item The Class protocol
52 This provides a means of manipulating and introspecting a Perl 5
53 class. It handles all of symbol table hacking for you, and provides
54 a rich set of methods that go beyond simple package introspection.
56 =item The Attribute protocol
58 This provides a consistent represenation for an attribute of a
59 Perl 5 class. Since there are so many ways to create and handle
60 atttributes in Perl 5 OO, this attempts to provide as much of a
61 unified approach as possible, while giving the freedom and
62 flexibility to subclass for specialization.
64 =item The Method protocol
66 This provides a means of manipulating and introspecting methods in
67 the Perl 5 object system. As with attributes, there are many ways to
68 approach this topic, so we try to keep it pretty basic, while still
69 making it possible to extend the system in many ways.
73 What follows is a more detailed documentation on each specific sub
76 =head2 The Class protocol
80 These methods handle creating Class objects, which can be used to
81 both create new classes, and analyze pre-existing ones.
83 Class::MOP will internally store weakened references to all the
84 instances you create with these methods, so that they do not need
85 to be created any more than nessecary.
89 =item B<create ($package_name, ?@superclasses, ?%methods, ?%attributes)>
91 This returns the basic Class object, bringing the specified
92 C<$package_name> into existence and adding any of the
93 C<@superclasses>, C<%methods> and C<%attributes> to it.
95 =item B<load ($package_name)>
97 This returns the basic Class object, after examining the given
98 C<$package_name> and attempting to discover it's components (the
99 methods, attributes and superclasses).
101 B<NOTE>: This method makes every attempt to ignore subroutines
102 which have been exported by other packages into this one.
104 =item B<initialize ($package_name, @superclasses, %methods, %attributes)>
106 This creates the actual Class object given a C<$package_name>,
107 an array of C<@superclasses>, a hash of C<%methods> and a hash
108 of C<%attributes>. This method is used by both C<load> and
111 This method also stores the Class object for you inside Class::MOP.
121 This is a read-only attribute which returns the package name that
122 the Class is stored in.
126 This is a read-only attribute which returns the C<$VERSION> of the
127 package the Class is stored in.
131 =head3 Inheritance Relationships
135 =item C<superclasses (?@superclasses)>
137 This is a read-write attribute which represents the superclass
138 relationships of this Class. Basically, it can get and set the
141 =item C<class_precendence_list>
143 This computes the a list of the Class's ancestors in the same order
144 in which method dispatch will be done.
152 =item C<add_method ($method_name, $method)>
154 This will take a C<$method_name> and CODE reference to that
155 C<$method> and install it into the Class.
157 B<NOTE> : This does absolutely nothing special to C<$method>
158 other than use B<Sub::Name> to make sure it is tagged with the
159 correct name, and therefore show up correctly in stack traces and
162 =item C<has_method ($method_name)>
164 This just provides a simple way to check if the Class implements
165 a specific C<$method_name>. It will I<not> however, attempt to check
166 if the class inherits the method.
168 =item C<get_method ($method_name)>
170 This will return a CODE reference of the specified C<$method_name>,
171 or return undef if that method does not exist.
173 =item C<remove_method ($method_name)>
175 This will attempt to remove a given C<$method_name> from the Class.
176 It will return the CODE reference that it has removed, and will
177 attempt to use B<Sub::Name> to clear the methods associated name.
179 =item C<get_method_list>
181 This will return a list of method names for all I<locally> defined
182 methods. It does B<not> provide a list of all applicable methods,
183 including any inherited ones. If you want a list of all applicable
184 methods, use the C<compute_all_applicable_methods> method.
186 =item C<compute_all_applicable_methods>
188 This will return a list of all the methods names this Class will
189 support, taking into account inheritance. The list will be a list of
190 HASH references, each one containing the following information; method
191 name, the name of the class in which the method lives and a CODE reference
192 for the actual method.
194 =item C<find_all_methods_by_name ($method_name)>
196 This will traverse the inheritence hierarchy and locate all methods
197 with a given C<$method_name>. Similar to C<compute_all_applicable_methods>
198 it returns a list of HASH references with the following information;
199 method name (which will always be the same as C<$method_name>), the name of
200 the class in which the method lives and a CODE reference for the actual method.
206 It should be noted that since there is no one consistent way to define the
207 attributes of a class in Perl 5. These methods can only work with the
208 information given, and can not easily discover information on their own.
230 =item "The Art of the Meta Object Protocol"
238 Stevan Little E<gt>stevan@iinteractive.comE<lt>
240 =head1 COPYRIGHT AND LICENSE
242 Copyright 2006 by Infinity Interactive, Inc.
244 L<http://www.iinteractive.com>
246 This library is free software; you can redistribute it and/or modify
247 it under the same terms as Perl itself.