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 <[email protected]>

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

   Copyright (c) 2011, 2012, 2017 Andrew Main (Zefram)

   This module is free software.

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