---
name: "B::Hooks::OP::Check::EntersubForCV"
section: "3pm"
platform: "linux"
package: "libb-hooks-op-check-entersubforcv-perl"
version: "0.10-3+b2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/B::Hooks::OP::Check::EntersubForCV"
---

# B::Hooks::OP::Check::EntersubForCV(3pm)

Invoke callbacks on construction of entersub OPs for certain CVs

## 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

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.