---
name: "Class::Data::Inheritable"
section: "3pm"
platform: "linux"
package: "perl-class-data-inheritable"
version: "0.10-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Class::Data::Inheritable"
---

# Class::Data::Inheritable(3pm)

Inheritable, overridable class data

## 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 overridden.

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 overridden a method:

```
  # Raygun has an orange suitcase, Pere::Ubu's is still Blue.
  Raygun->Suitcase('Orange');
```

Now that Raygun has overridden Pere::Ubu further 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@rt.cpan.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.