


Devel::SelfStubbePerl)Programmers ReferenceDevel::SelfStubber(3p)


NAME
       Devel::SelfStubber - generate stubs for a SelfLoading mod-
       ule

SYNOPSIS
       To generate just the stubs:

           use Devel::SelfStubber;
           Devel::SelfStubber->stub('MODULENAME','MY_LIB_DIR');

       or to generate the whole module with stubs inserted cor-
       rectly

           use Devel::SelfStubber;
           $Devel::SelfStubber::JUST_STUBS=0;
           Devel::SelfStubber->stub('MODULENAME','MY_LIB_DIR');

       MODULENAME is the Perl module name, e.g. Devel::SelfStub-
       ber, NOT 'Devel/SelfStubber' or 'Devel/SelfStubber.pm'.

       MY_LIB_DIR defaults to '.' if not present.

DESCRIPTION
       Devel::SelfStubber prints the stubs you need to put in the
       module before the __DATA__ token (or you can get it to
       print the entire module with stubs correctly placed). The
       stubs ensure that if a method is called, it will get
       loaded. They are needed specifically for inherited
       autoloaded methods.

       This is best explained using the following example:

       Assume four classes, A,B,C & D.

       A is the root class, B is a subclass of A, C is a subclass
       of B, and D is another subclass of A.

                               A
                              / \
                             B   D
                            /
                           C

       If D calls an autoloaded method 'foo' which is defined in
       class A, then the method is loaded into class A, then exe-
       cuted. If C then calls method 'foo', and that method was
       reimplemented in class B, but set to be autoloaded, then
       the lookup mechanism never gets to the AUTOLOAD mechanism
       in B because it first finds the method already loaded in
       A, and so erroneously uses that. If the method foo had
       been stubbed in B, then the lookup mechanism would have
       found the stub, and correctly loaded and used the sub from
       B.




1997-11-30                 perl v5.6.1                          1





Devel::SelfStubbePerl)Programmers ReferenceDevel::SelfStubber(3p)


       So, for classes and subclasses to have inheritance cor-
       rectly work with autoloading, you need to ensure stubs are
       loaded.

       The SelfLoader can load stubs automatically at module ini-
       tialization with the statement 'Self-
       Loader->load_stubs()';, but you may wish to avoid having
       the stub loading overhead associated with your initializa-
       tion (though note that the SelfLoader::load_stubs method
       will be called sooner or later - at latest when the first
       sub is being autoloaded). In this case, you can put the
       sub stubs before the __DATA__ token. This can be done man-
       ually, but this module allows automatic generation of the
       stubs.

       By default it just prints the stubs, but you can set the
       global $Devel::SelfStubber::JUST_STUBS to 0 and it will
       print out the entire module with the stubs positioned cor-
       rectly.

       At the very least, this is useful to see what the Self-
       Loader thinks are stubs - in order to ensure future ver-
       sions of the SelfStubber remain in step with the Self-
       Loader, the SelfStubber actually uses the SelfLoader to
       determine which stubs are needed.
































1997-11-30                 perl v5.6.1                          2


