Apache::Symbol - Things for symbol things

SYNOPSIS

        use Apache::Symbol ();

        @ISA = qw(Apache::Symbol);

DESCRIPTION

       perlsub/Constant Functions says:

        If you redefine a subroutine which was eligible for inlining you'll get
        a mandatory warning.  (You can use this warning to tell whether or not a
        particular subroutine is considered constant.)  The warning is
        considered severe enough not to be optional because previously compiled
        invocations of the function will still be using the old value of the
        function.

       mandatory warning means there is _no_ way to avoid this
       warning no matter what tricks you pull in Perl.  This is
       bogus for us mod_perl users when restarting the server
       with PerlFreshRestart on or when Apache::StatINC pulls in
       a module that has changed on disk.

       You can, however, pull some tricks with XS to avoid this
       warning, Apache::Symbol::undef does just that.

ARGUMENTS

       `undef_functions' takes two arguments: `skip' and
       `only_undef_exports'.

       `skip' is a regular expression indicating the function
       names to skip.

       Use the `only_undef_exports' flag to undef only those
       functions which are listed in `@EXPORT', `@EXPORT_OK',
       `%EXPORT_TAGS', or `@EXPORT_EXTRAS'.  `@EXPORT_EXTRAS' is
       not used by the Exporter, it is only exists to communicate
       with `undef_functions'.

       As a special case, if none of the EXPORT variables are
       defined ignore `only_undef_exports'.  This takes care of
       trivial modules that don't use the Exporter.

ARGUMENTS

       `undef_functions' takes two arguments: `skip' and
       `only_undef_exports'.

       `skip' is a regular expression indicating the function
       names to skip.

       Use the `only_undef_exports' flag to undef only those
       not used by the Exporter, it is only exists to communicate
       with `undef_functions'.

       As a special case, if none of the EXPORT variables are
       defined ignore `only_undef_exports'.  This takes care of
       trivial modules that don't use the Exporter.

PLAYERS

       This module and the undefining of functions is optional,
       if you wish to have this functionality enabled, there are
       one or more switches you need to know about.

       PerlRestartHandler
           Apache::Symbol defines a PerlRestartHandler which can
           be useful in conjuction with `PerlFreshRestart On' as
           it will avoid subroutine redefinition messages.  Con-
           figure like so:

            PerlRestartHandler Apache::Symbol

       Apache::Registry
           By placing the SYNOPSIS bit in you script,
           Apache::Registry will undefine subroutines in your
           script before it is re-compiled to avoid "subroutine
           re-defined" warnings.

       Apache::StatINC
           See Apache::StatINC's docs.

       APACHE_SYMBOL_UNIVERSAL
           If this environment variable is true when Symbol.pm is
           compiled, it will define UNIVERSAL::undef_functions,
           which means all classes will inherit Apache::Sym-
           bol::undef_functions.

       Others
           Module such as HTML::Embperl and Apache::ePerl who
           compile and script cache scripts ala Apache::Registry
           style can use `undef_functions' with this bit of code:

               if($package->can('undef_functions')) {
                   $package->undef_functions;
               }

           Where `$package' is the name of the package in which
           the script is being re-compiled.

SEE ALSO

       perlsub(1), Devel::Symdump(3)

AUTHOR