base(3p) Perl Programmers Reference Guide base(3p) #

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

NNAAMMEE #

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

SSYYNNOOPPSSIISS #

     package Baz;
     use base qw(Foo Bar);

DDEESSCCRRIIPPTTIIOONN #

 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 _F_o_o_._p_m, but because "Foo" defines a symbol (the "exclaim"
 subroutine), "base" will not die when the "require" fails to load _F_o_o_._p_m.

 "base" will also initialize the fields if one of the base classes has it.
 Multiple inheritance of fields is NNOOTT 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 nnoott called.

DDIIAAGGNNOOSSTTIICCSS #

 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';

HHIISSTTOORRYY #

 This module was introduced with Perl 5.004_04.

CCAAVVEEAATTSS #

 Due to the limitations of the implementation, you must use base _b_e_f_o_r_e
 you declare any of your own fields.

SSEEEE AALLSSOO #

 fields

perl v5.36.3 2019-02-13 base(3p)