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class::data::inheritable(3) [osx man page]

Class::Data::Inheritable(3)				User Contributed Perl Documentation			       Class::Data::Inheritable(3)

Class::Data::Inheritable - Inheritable, overridable class data SYNOPSIS
package Stuff; use base qw(Class::Data::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'); # Or, all in one shot: Stuff->mk_classdata(DataFile => '/etc/stuff/data'); DESCRIPTION
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. For example: 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. $suitcase = Raygun->Suitcase; Raygun inherits its Suitcase class data from Pere::Ubu. Inheritance of class data works analogous to method inheritance. As long as Raygun does not "override" its inherited class data (by using Suitcase() to set a new value) it will continue to use whatever is set in Pere::Ubu and inherit further changes: # Both Raygun's and Pere::Ubu's suitcases are now Blue Pere::Ubu->Suitcase('Blue'); However, should Raygun decide to set its own Suitcase() it has now "overridden" Pere::Ubu and is on its own, just like if it had overriden a method: # Raygun has an orange suitcase, Pere::Ubu's is still Blue. Raygun->Suitcase('Orange'); Now that Raygun has overridden Pere::Ubu futher changes by Pere::Ubu no longer effect Raygun. # Raygun still has an orange suitcase, but Pere::Ubu is using Samsonite. Pere::Ubu->Suitcase('Samsonite'); Methods mk_classdata Class->mk_classdata($data_accessor_name); Class->mk_classdata($data_accessor_name => $value); 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 $data_accessor_name, and optionally initially setting it to the given value. To facilitate overriding, mk_classdata creates an alias to the accessor, _field_accessor(). So Suitcase() would have an alias _Suitcase_accessor() that does the exact same thing as Suitcase(). This is useful if you want to alter the behavior of a single accessor yet still get the benefits of inheritable class data. For example. sub Suitcase { my($self) = shift; warn "Fashion tragedy" if @_ and $_[0] eq 'Plaid'; $self->_Suitcase_accessor(@_); } AUTHOR
Original code by Damian Conway. Maintained by Michael G Schwern until September 2005. Now maintained by Tony Bowden. BUGS and QUERIES Please direct all correspondence regarding this module to: COPYRIGHT and LICENSE Copyright (c) 2000-2005, Damian Conway and Michael G Schwern. All Rights Reserved. This module is free software. It may be used, redistributed and/or modified under the same terms as Perl itself. SEE ALSO
perltooc has a very elaborate discussion of class data in Perl. perl v5.16.2 2008-01-25 Class::Data::Inheritable(3)

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MakeMethods::Template::Inheritable(3pm) 		User Contributed Perl Documentation		   MakeMethods::Template::Inheritable(3pm)

Class::MakeMethods::Template::Inheritable - Overridable data SYNOPSIS
package MyClass; use Class::MakeMethods( 'Template::Inheritable:scalar' => 'foo' ); # We now have an accessor method for an "inheritable" scalar value MyClass->foo( 'Foozle' ); # Set a class-wide value print MyClass->foo(); # Retrieve class-wide value my $obj = MyClass->new(...); print $obj->foo(); # All instances "inherit" that value... $obj->foo( 'Foible' ); # until you set a value for an instance. print $obj->foo(); # This now finds object-specific value. ... package MySubClass; @ISA = 'MyClass'; print MySubClass->foo(); # Intially same as superclass, MySubClass->foo('Foobar'); # but overridable per subclass, print $subclass_obj->foo(); # and shared by its instances $subclass_obj->foo('Fosil');# until you override them... ... DESCRIPTION
The MakeMethods subclass provides accessor methods that search an inheritance tree to find a value. This allows you to set a shared or default value for a given class, and optionally override it in a subclass. Standard Methods The following methods from Generic should be supported: scalar string string_index (?) number boolean (?) bits (?) array (?) hash (?) tiedhash (?) hash_of_arrays (?) object (?) instance (?) array_of_objects (?) code (?) code_or_scalar (?) See Class::MakeMethods::Template::Generic for the interfaces and behaviors of these method types. The items marked with a * above are specifically defined in this package, whereas the others are formed automatically by the interaction of this package's generic settings with the code templates provided by the Generic superclass. The items marked with a ? above have not been tested sufficiently; please inform the author if they do not function as you would expect. SEE ALSO
See Class::MakeMethods for general information about this distribution. See Class::MakeMethods::Template for more about this family of subclasses. See Class::MakeMethods::Template::Generic for information about the various accessor interfaces subclassed herein. If you just need scalar accessors, see Class::Data::Inheritable for a very elegant and efficient implementation. perl v5.10.1 2004-09-06 MakeMethods::Template::Inheritable(3pm)
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