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Class::Data::Inheritable(3) User Contributed Perl Documentation Class::Data::Inheritable(3)
NAME
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:
bug-Class-Data-Inheritable AT rt.org
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 v5.16.3 2008-01-25 Class::Data::Inheritable(3)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2024-04-16 10:34 @3.149.234.251 CrawledBy claudebot