base(3pm) [redhat man page]

base(3pm)						 Perl Programmers Reference Guide						 base(3pm)

NAME

       base - Establish IS-A relationship with base class at compile time

SYNOPSIS

	   package Baz;
	   use base qw(Foo Bar);

DESCRIPTION

       Roughly similar in effect to

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

       Will also initialize the %FIELDS hash if one of the base classes has it.  Multiple inheritance of %FIELDS is not supported.  The 'base'
       pragma will croak if multiple base classes have a %FIELDS hash.	See fields for a description of this feature.

       When strict 'vars' is in scope base also let you assign to @ISA without having to declare @ISA with the 'vars' pragma first.

       If any of the base classes are not loaded yet, base silently "require"s them.  Whether to "require" a base class package is determined by
       the absence of a global $VERSION in the base package.  If $VERSION is not detected even after loading it, <base> will define $VERSION in
       the base package, setting it to the string "-1, set by base.pm".

HISTORY

       This module was introduced with Perl 5.004_04.

SEE ALSO

       fields

perl v5.8.0							    2002-06-01								 base(3pm)

base(3pm)						 Perl Programmers Reference Guide						 base(3pm)

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 discouraged in favor of the lighter-weight "parent".

       Allows you to both load one or more modules, while setting up inheritance from those 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 find the module's file, but will die on any other error.  After all
       this, should your base class be empty, containing no symbols, "base" will die. This is useful for inheriting from classes in the same file
       as yourself but where the 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 "exclaim" subroutine), "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 classes each have inheritable fields the 'base' pragma will croak. See fields for 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 not found 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 use base before you declare any of your own fields.

SEE ALSO

       fields

perl v5.16.3							    2013-03-04								 base(3pm)