NAME
    Sub::Op - Install subroutines as opcodes.

VERSION
    Version 0.02

SYNOPSIS
    In your XS file :

        #include "sub_op.h"

        STATIC OP *scalar_util_reftype(pTHX) {
         dSP;
         dMARK;
         SV *sv = POPs;
         if (SvMAGICAL(sv))
          mg_get(sv);
         if (SvROK(sv))
          PUSHs(sv_reftype(SvRV(sv), 0));
         else
          PUSHs(&PL_sv_undef);
         RETURN;
        }

        MODULE = Scalar::Util::Ops       PACKAGE = Scalar::Util::Ops

        BOOT:
        {
         sub_op_config_t c;
         c.name    = "reftype";
         c.namelen = sizeof("reftype")-1;
         c.pp      = scalar_util_reftype;
         c.check   = 0;
         c.ud      = NULL;
         sub_op_register(aTHX_ &c);
        }

    In your Perl module file :

        package Scalar::Util::Ops;

        use strict;
        use warnings;

        our ($VERSION, @ISA);

        use Sub::Op; # Before loading our own shared library

        BEGIN {
         $VERSION = '0.01';
         require DynaLoader;
         push @ISA, 'DynaLoader';
         __PACKAGE__->bootstrap($VERSION);
        }

        sub import   { Sub::Op::enable(reftype => scalar caller) }

        sub unimport { Sub::Op::disable(reftype => scalar caller) }

        1;

    In your Makefile.PL :

        use ExtUtils::Depends;

        my $ed = ExtUtils::Depends->new('Scalar::Util::Ops' => 'Sub::Op');

        WriteMakefile(
         $ed->get_makefile_vars,
         ...
        );

DESCRIPTION
    This module provides a C and Perl API for replacing subroutine calls by
    custom opcodes. This has two main advantages :

    *   it gets rid of the overhead of a normal subroutine call ;

    *   there's no symbol table entry defined for the subroutine.

    Subroutine calls with and without parenthesis are handled. Ampersand
    calls are not replaced, and as such will still allow to call a
    subroutine with same name defined earlier. This may or may not be
    considered as a bug, but it gives the same semantics as Perl keywords,
    so I believe it's reasonable.

    When B and B::Deparse are loaded, they get automatically monkeypatched
    so that introspecting modules like B::Concise and B::Deparse still
    produce a valid output.

C API
  "sub_op_config_t"
    A typedef'd struct that configures how Sub::Op should handle a given
    subroutine name. It has the following members :

    *   "const char *name"

        The name of the subroutine you want to replace. Allowed to be
        static.

    *   "STRLEN namelen"

        "name"'s length, in bytes.

    *   "Perl_ppaddr_t pp"

        The pp function that will be called instead of the subroutine.
        "Perl_ppaddr_t" is a typedef'd function pointer defined by perl as :

            typedef OP *(*Perl_ppaddr_t)(pTHX);

    *   "sub_op_check_t check"

        An optional callback that will be called each time a call to "name"
        is replaced. You can use it to attach extra info to those ops (e.g.
        with a pointer table) or to perform more optimizations to the
        optree. "sub_op_check_t" is a typedef'd function pointer defined by
        :

            typedef OP *(*sub_op_check_t)(pTHX_ OP *, void *);

    *   "void *ud"

        An optional user data passed to the "check" callback.

  "void sub_op_register(pTHX_ const sub_op_config_t *c)"
    Registers a name and its configuration into Sub::Op. The caller is
    responsible for allocating and freeing the "sub_op_config_t" object. No
    pointer to it or to its members is kept.

PERL API
  "enable $name, [ $pkg ]"
    Enable the replacement with a custom opcode of calls to the $name
    subroutine of the $pkg package in the current lexical scope. A pp
    callback must have been registered for $name by calling the C function
    "sub_op_register" in the XS section of your module.

    When $pkg is not set, it defaults to the caller package.

  "disable $name, [ $pkg ]"
    Disable the replacement for calls to $name in the package $pkg.

    When $pkg is not set, it defaults to the caller package.

EXAMPLES
    See the t/Sub-Op-LexicalSub directory that implements a complete
    example.

CAVEATS
    Preexistent definitions of a sub whose name is handled by Sub::Op are
    restored at the end of the lexical scope in which the module is used.
    But if you define a sub in the scope of action of Sub::Op with a name
    that is currently being replaced, the new declaration will be
    obliterated at the scope end.

    Function calls without parenthesis inside an "eval STRING" in the scope
    of the pragma won't be replaced. I know a few ways of fixing this, but
    I've not yet decided on which.

DEPENDENCIES
    perl 5.10.

    Variable::Magic, B::Hooks::EndOfScope.

    ExtUtils::Depends.

SEE ALSO
    subs::auto.

    B::Hooks::XSUB::CallAsOp provides a C API to declare XSUBs that
    effectively call a specific PP function. Thus, it allows you to write
    XSUBs with the PP stack conventions used for implementing perl core
    keywords. There's no opcode replacement and no parsing hacks.

    B::Hooks::OP::Check::EntersubForCV.

AUTHOR
    Vincent Pit, "<perl at profvince.com>", <http://www.profvince.com>.

    You can contact me by mail or on "irc.perl.org" (vincent).

BUGS
    Please report any bugs or feature requests to "bug-sub-op at
    rt.cpan.org", or through the web interface at
    <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Sub-Op>. I will be
    notified, and then you'll automatically be notified of progress on your
    bug as I make changes.

SUPPORT
    You can find documentation for this module with the perldoc command.

        perldoc Sub::Op

    Tests code coverage report is available at
    <http://www.profvince.com/perl/cover/Sub-Op>.

COPYRIGHT & LICENSE
    Copyright 2010 Vincent Pit, all rights reserved.

    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

