NAME
    B::Hooks::OP::Check::EntersubForCV - Invoke callbacks on construction of
    entersub OPs for certain CVs

SYNOPSIS
  From Perl
        sub foo {}

        use B::Hooks::OP::Check::EntersubForCV
            \&foo => sub { warn "entersub for foo() being compiled" };

        foo(); # callback is invoked when this like is compiled

        no B::Hooks::OP::Check::EntersubForCV \&foo;

        foo(); # callback isn't invoked

  From C/XS
        #include "hook_op_check_entersubforcv.h"

        STATIC OP *
        my_callback (pTHX_ OP *op, CV *cv, void *user_data) {
            /* ... */
            return op;
        }

        hook_op_check_id id;

        /* register callback */
        id = hook_op_check_entersubforcv (cv, my_callback, NULL);

        /* unregister */
        hook_op_check_entersubforcv_remove (id);

DESCRIPTION
Perl API
  import / register
        use B::Hooks::OP::Check::EntersubForCV
            \&code => \&handler;

        # or
        my $id = B::Hooks::OP::Check::EntersubForCV::register(\&code => \&handler);

    Register "handler" to be executed when an entersub opcode for the CV
    "code" points to is compiled.

    When using "register" an id that can be used for later removal of the
    handler using "unregister" is returned.

  unimport / unregister
        no B::Hooks::OP::Check::EntersubForCV \&code;

        # or
        B::Hooks::OP::Check::EntersubForCV::unregister($id);

    Stop calling the registered handler for "code" for all entersubs after
    this.

C API
  TYPES
   OP *(*hook_op_check_entersubforcv_cb) (pTHX_ OP *, CV *, void *)
    The type the handlers need to implement.

  FUNCTIONS
   hook_op_check_id hook_op_check_entersubforcv (CV *cv, hook_op_check_entersubforcv_cb cb, void *user_data)
    Register the callback "cb" to be called when an entersub opcode for "cv"
    is compiled. "user_data" will be passed to the callback as the last
    argument.

    Returns an id that can be used to remove the handler using
    "hook_op_check_entersubforcv_remove".

   void *hook_op_check_entersubforcv_remove (hook_op_check_id id)
    Remove a previously registered handler referred to by "id".

    Returns the user data that was associated with the handler.

SEE ALSO
    B::Hooks::OP::Check

AUTHOR
    Florian Ragwitz <rafl@debian.org>

COPYRIGHT AND LICENSE
    Copyright (c) 2008, 2009 Florian Ragwitz

    This module is free software.

    You may distribute this code under the same terms as Perl itself.