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Intel Software Development Emulator 1.70 (Default branch)
01-31-2009
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MakeMethods::Emulator::Inheritable(3pm) User Contributed Perl Documentation MakeMethods::Emulator::Inheritable(3pm) NAME
Class::MakeMethods::Emulator::Inheritable - Emulate Class::Inheritable SYNOPSIS
package Stuff; use base qw(Class::MakeMethods::Emulator::Inheritable); # Set up DataFile as inheritable class data. Stuff->mk_classdata('DataFile'); # Declare the location of the data file for this class. Stuff->DataFile('/etc/stuff/data'); DESCRIPTION
This module is an adaptor that provides emulatation of Class::Data::Inheritable by invoking similiar functionality provided by Class::MakeMethods::ClassInherit. The public interface provided by Class::MakeMethods::Emulator::Inheritable is identical to that of Class::Data::Inheritable. Class::Data::Inheritable is for creating accessor/mutators to class data. That is, if you want to store something about your class as a whole (instead of about a single object). This data is then inherited by your subclasses and can be overriden. USAGE
As specified by Class::Data::Inheritable, clients should inherit from this module and then invoke the mk_classdata() method for each class method desired: Class->mk_classdata($data_accessor_name); This is a class method used to declare new class data accessors. A new accessor will be created in the Class using the name from $data_accessor_name. Class->mk_classdata($data_accessor_name, $initial_value); You may also pass a second argument to initialize the value. To facilitate overriding, mk_classdata creates an alias to the accessor, _field_accessor(). So Suitcase() would have an alias _Suitcase_accessor() that does the exact same thing as Suitcase(). This is useful if you want to alter the behavior of a single accessor yet still get the benefits of inheritable class data. For example. sub Suitcase { my($self) = shift; warn "Fashion tragedy" if @_ and $_[0] eq 'Plaid'; $self->_Suitcase_accessor(@_); } COMPATIBILITY
Note that the internal implementation of Class::MakeMethods::ClassInherit does not match that of Class::Data::Inheritable. In particular, Class::Data::Inheritable installs new methods in subclasses when they first initialize their value, while EXAMPLE
The example provided by Class::Data::Inheritable is equally applicable to this emulator. package Pere::Ubu; use base qw(Class::MakeMethods::Emulator::Inheritable); Pere::Ubu->mk_classdata('Suitcase'); will generate the method Suitcase() in the class Pere::Ubu. This new method can be used to get and set a piece of class data. Pere::Ubu->Suitcase('Red'); $suitcase = Pere::Ubu->Suitcase; The interesting part happens when a class inherits from Pere::Ubu: package Raygun; use base qw(Pere::Ubu); # Raygun's suitcase is Red. $suitcase = Raygun->Suitcase; Raygun inherits its Suitcase class data from Pere::Ubu. Inheritance of class data works analgous to method inheritance. As long as Raygun does not "override" its inherited class data (by using Suitcase() to set a new value) it will continue to use whatever is set in Pere::Ubu and inherit further changes: # Both Raygun's and Pere::Ubu's suitcases are now Blue Pere::Ubu->Suitcase('Blue'); However, should Raygun decide to set its own Suitcase() it has now "overridden" Pere::Ubu and is on its own, just like if it had overriden a method: # Raygun has an orange suitcase, Pere::Ubu's is still Blue. Raygun->Suitcase('Orange'); Now that Raygun has overridden Pere::Ubu futher changes by Pere::Ubu no longer effect Raygun. # Raygun still has an orange suitcase, but Pere::Ubu is using Samsonite. Pere::Ubu->Suitcase('Samsonite'); SEE ALSO
See Class::MakeMethods for general information about this distribution. See Class::MakeMethods::Emulator for more about this family of subclasses. See Class::Data::Inheritable for documentation of the original module. See perltootc for a discussion of class data in Perl. See Class::MakeMethods::Standard::Inheritable and Class::MakeMethods::Template::ClassInherit for inheritable data methods. perl v5.10.1 2004-09-06 MakeMethods::Emulator::Inheritable(3pm)