Devel::SelfStubber

Devel::SelfStubber(3)  Perl Programmers Reference Guide  Devel::SelfStubber(3)



NAME
       Devel::SelfStubber - generate stubs for a SelfLoading module

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 correctly

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

       MODULENAME is the Perl module name, e.g. Devel::SelfStubber, 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 executed. 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.

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

       The SelfLoader can load stubs automatically at module initialization
       with the statement 'SelfLoader->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 manually, 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 correctly.

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



perl v5.8.6                       2001-09-21             Devel::SelfStubber(3)