Going on what you're doing here I suppose you want have weak references. Take a look at Scalar::Util's weaken() function.

How can I weaken reference ($copy in example above) if i don't know about it existence? Is it possible to obtain all references that refer to specified object?

How do you know there are references then?

Please explain why you'd want to do this, because you're trying to do something that you'd normally never want to do, and perl is in fact designed to stop you doing this.

Any way, if i had to, I'd probably resort to Tie::Scalar to fake a reference and return weak-references whenever someone tries to copy it*). Very non-intuitive, slow and confusing, but at least sort of portable. Also, that way you could throw some stack-traces to STDERR to see where the **** your references get copied.

*) now that I think about it, I'm not even sure that would work.

"What should it profit a man, if he should win a flame war, yet lose his cool?"

Btw, what's the reason you are trying to do this? This smells like a bug in your application design to me.

---

Ordinary morality is for ordinary people. -- Aleister Crowley

Consult sv.c about the arenas. This is where everything perl manages is managed. You'll write some C which can be used by the visit() function. That function can find your SV heads where SvANY() == your pointer. I'd guess you'd zero the refcount and call sv_clear on it then. I've included a copy of a simple function that uses visit() just so you can see how short and easy this can be.

    visit(do_report_used, 0, 0);

static void
do_report_used(pTHX_ SV *sv)
{
    if (SvTYPE(sv) != SVTYPEMASK) {
        PerlIO_printf(Perl_debug_log, "****\n");
        sv_dump(sv);
    }
}
[download]

Except that isn't part of the Perl API and is subject to change, so it's not to be recommended. Also, visit() is a static function which can't be used outside of sv.c, and who's prototype has changed between 5.8.0 and 5.8.8.

To answer the OP: no, there's no official way to achieve this.

Dave.

It's still a better way to accomplish this dubious goal than other ways. At least this way the infrastructure for walking this stuff is getting used. Now the OP can expect breakage between versions of perl...

⠤⠤ ⠙⠊⠕⠞⠁⠇⠑⠧⠊

There is Devel::FindRef, but even its documentation says This is a quick hack only. As the others already said, there is no official way.