Establish an ISA relationship with base classes at compile time

Daftar Isi

NAME
SYNOPSIS
DESCRIPTION
DIAGNOSTICS
HISTORY
CAVEATS
SEE ALSO

NAME

base - Establish an ISA relationship with base classes at compile time

SYNOPSIS

 package Baz;
  use base qw(Foo Bar);

DESCRIPTION

Unless you are using the fields pragma, consider this module discouragedin favor of the lighter-weight parent.

Allows you to both load one or more modules, while setting up inheritance fromthose modules at the same time. Roughly similar in effect to

 package Baz;
  BEGIN {
  require Foo;
  require Bar;
  push @ISA, qw(Foo Bar);
  }

When base tries to require a module, it will not die if it cannot findthe module's file, but will die on any other error. After all this, shouldyour base class be empty, containing no symbols, base will die. This isuseful for inheriting from classes in the same file as yourself but wherethe filename does not match the base module name, like so:

 # in Bar.pm
  package Foo;
  sub exclaim { "I can have such a thing?!" }
 
  package Bar;
  use base "Foo";

There is no Foo.pm, but because Foo defines a symbol (the exclaimsubroutine), base will not die when the require fails to load Foo.pm.

base will also initialize the fields if one of the base classes has it.Multiple inheritance of fields is NOT supported, if two or more base classeseach have inheritable fields the 'base' pragma will croak. See fieldsfor a description of this feature.

The base class' import method is not called.

DIAGNOSTICS

Base class package "%s" is empty.
base.pm was unable to require the base package, because it was notfound in your path.
Class 'Foo' tried to inherit from itself
Attempting to inherit from yourself generates a warning.
```
 package Foo;
  use base 'Foo';
 
```

HISTORY

This module was introduced with Perl 5.004_04.

CAVEATS

Due to the limitations of the implementation, you must usebase before you declare any of your own fields.