NAME
    B::Hooks::OP::Check::StashChange - Invoke callbacks when the stash code
    is being compiled in changes

SYNOPSIS
  From Perl
        package Foo;

        use B::Hooks::OP::Check::StashChange;

        our $id = B::Hooks::OP::Check::StashChange::register(sub {
            my ($new, $old) = @_;
            warn "${old} -> ${new}";
        });

        package Bar; # "Foo -> Bar"

        B::Hooks::OP::Check::StashChange::unregister($Foo::id);

        package Moo; # callback not invoked

  From C/XS
        #include "hooks_op_check_stashchange.h"

        STATIC OP *
        my_callback (pTHX_ OP *op, char *new_stash, char *old_stash, void *user_data) {
            /* ... */
            return op;
        }

        UV id;

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

        /* unregister */
        hook_op_check_stashchange_remove (id);

DESCRIPTION
Perl API
  register
        B::Hooks::OP::Check::

        # or
        my $id = B::Hooks::OP::Check::StashChange::register(\&callback);

    Register "callback" when an opcode is being compiled in a different
    namespace than the previous one.

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

  unregister
        B::Hooks::OP::Check::StashChange::unregister($id);

    Disable the callback referenced by $id.

C API
  TYPES
   OP *(*hook_op_check_stashchange_cb) (pTHX_ OP *op, const char *new_stash, const char *old_stash, void *user_data)
    The type the callbacks need to implement.

  FUNCTIONS
   UV hook_op_check_stashchange (hook_op_check_stashchange_cb cb, void *user_data)
    Register the callback "cb" to be when an opcode is compiled in a
    different namespace than the previous. "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_stashchange_remove".

   void *hook_op_check_stashchange_remove (UV 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 Florian Ragwitz

    This module is free software.

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