1MakeMethods::Emulator::UIsnehrerCiotnatbrlieb(u3t)ed PerMlakDeoMceutmheondtsa:t:iEomnulator::Inheritable(3)
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NAME

6       Class::MakeMethods::Emulator::Inheritable - Emulate Class::Inheritable
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SYNOPSIS

9         package Stuff;
10         use base qw(Class::MakeMethods::Emulator::Inheritable);
11
12         # Set up DataFile as inheritable class data.
13         Stuff->mk_classdata('DataFile');
14
15         # Declare the location of the data file for this class.
16         Stuff->DataFile('/etc/stuff/data');
17

DESCRIPTION

19       This module is an adaptor that provides emulatation of
20       Class::Data::Inheritable by invoking similiar functionality provided by
21       Class::MakeMethods::ClassInherit.
22
23       The public interface provided by Class::MakeMethods::Emulator::Inheri‐
24       table is identical to that of Class::Data::Inheritable.
25
26       Class::Data::Inheritable is for creating accessor/mutators to class
27       data.  That is, if you want to store something about your class as a
28       whole (instead of about a single object).  This data is then inherited
29       by your subclasses and can be overriden.
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USAGE

32       As specified by Class::Data::Inheritable, clients should inherit from
33       this module and then invoke the mk_classdata() method for each class
34       method desired:
35
36         Class->mk_classdata($data_accessor_name);
37
38       This is a class method used to declare new class data accessors.  A new
39       accessor will be created in the Class using the name from $data_acces‐
40       sor_name.
41
42         Class->mk_classdata($data_accessor_name, $initial_value);
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44       You may also pass a second argument to initialize the value.
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46       To facilitate overriding, mk_classdata creates an alias to the acces‐
47       sor, _field_accessor().  So Suitcase() would have an alias _Suit‐
48       case_accessor() that does the exact same thing as Suitcase().  This is
49       useful if you want to alter the behavior of a single accessor yet still
50       get the benefits of inheritable class data.  For example.
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52         sub Suitcase {
53             my($self) = shift;
54             warn "Fashion tragedy" if @_ and $_[0] eq 'Plaid';
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56             $self->_Suitcase_accessor(@_);
57         }
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COMPATIBILITY

60       Note that the internal implementation of Class::MakeMethods::ClassIn‐
61       herit does not match that of Class::Data::Inheritable. In particular,
62       Class::Data::Inheritable installs new methods in subclasses when they
63       first initialize their value, while
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EXAMPLE

66       The example provided by Class::Data::Inheritable is equally applicable
67       to this emulator.
68
69         package Pere::Ubu;
70         use base qw(Class::MakeMethods::Emulator::Inheritable);
71         Pere::Ubu->mk_classdata('Suitcase');
72
73       will generate the method Suitcase() in the class Pere::Ubu.
74
75       This new method can be used to get and set a piece of class data.
76
77         Pere::Ubu->Suitcase('Red');
78         $suitcase = Pere::Ubu->Suitcase;
79
80       The interesting part happens when a class inherits from Pere::Ubu:
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82         package Raygun;
83         use base qw(Pere::Ubu);
84
85         # Raygun's suitcase is Red.
86         $suitcase = Raygun->Suitcase;
87
88       Raygun inherits its Suitcase class data from Pere::Ubu.
89
90       Inheritance of class data works analgous to method inheritance.  As
91       long as Raygun does not "override" its inherited class data (by using
92       Suitcase() to set a new value) it will continue to use whatever is set
93       in Pere::Ubu and inherit further changes:
94
95         # Both Raygun's and Pere::Ubu's suitcases are now Blue
96         Pere::Ubu->Suitcase('Blue');
97
98       However, should Raygun decide to set its own Suitcase() it has now
99       "overridden" Pere::Ubu and is on its own, just like if it had overriden
100       a method:
101
102         # Raygun has an orange suitcase, Pere::Ubu's is still Blue.
103         Raygun->Suitcase('Orange');
104
105       Now that Raygun has overridden Pere::Ubu futher changes by Pere::Ubu no
106       longer effect Raygun.
107
108         # Raygun still has an orange suitcase, but Pere::Ubu is using Samsonite.
109         Pere::Ubu->Suitcase('Samsonite');
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SEE ALSO

112       See Class::MakeMethods for general information about this distribution.
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114       See Class::MakeMethods::Emulator for more about this family of sub‐
115       classes.
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117       See Class::Data::Inheritable for documentation of the original module.
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119       See perltootc for a discussion of class data in Perl.
120
121       See Class::MakeMethods::Standard::Inheritable and Class::MakeMeth‐
122       ods::Template::ClassInherit for inheritable data methods.
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126perl v5.8.8                       2004-09-M0a6keMethods::Emulator::Inheritable(3)
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