---
name: "Class::MakeMethods::Emulator::Inheritable"
section: "3pm"
platform: "linux"
package: "libclass-makemethods-perl"
version: "1.01-7"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Class::MakeMethods::Emulator::Inheritable"
---

# Class::MakeMethods::Emulator::Inheritable(3pm)

Emulate Class::Inheritable

## 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 similar 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 overridden.

## 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 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');
```

## 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.