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(3)
perl v5.38.2 2023-11-28 base(3pm)
perl 5.38.2 - Generated Sun Dec 15 13:10:18 CST 2024