No, at that point they are in scope. But the problem is, they are referenced within the object (and used in another XS method). Perl thinks they are out of scope after the constructor is called, but this isn't the case here.

Okay. I get what you're saying now -- it would have been a whole lot clearer if you'd provided a full example; or were more precise in your description...

They don't go out of scope in the constructor, not even immediately on return from it. They go out of scope when you reach the end of the block (subroutine or package) in which they were defined (my). Ie. they act exactly like normal perl lexical variables.

You don't want them to act like normal perl variables, because you're storing them inside your XS structure, which perl doesn't know anything about, and so it duly GC's them once their Perl scope comes to an end.

This means I need to increase the reference count and this is the part I don't know how to do in XS. How do I increase the reference count in the constructor, where I get the two objects (and decrease upon destroy).

If my latest guess is correct -- you don't make it easy -- this is less about how to programmically increment and decrement the reference counts, but rather when to do so.

And actually, you seem to have a pretty clear handle on that: You increment it when you first store it into your XS structure; and decrement it a) if you overwrite it with a different value; or b) when you are destroying the structure. (Ie. Add a DESTROY) method for the Call object.

Maybe you already tried this and it didn't work? Gave errors?

The problem is that you are using the T_PTROBJ typemap; and by the time your XS code gets control, the reference has already been unwrapped -- by the XS generated typemap code -- and what you get is not the SV_ref, but the value you put inside it. Which is useful, most times, but not if you need to manipulate the ref counts.

The solution is to move from T_PTROBJ to T_OPAQUE, which means your XS code will be given the svref itself; which will allow you to manipulate the refcount; but also require you to unwrap the reference pointer yourself.

If you posted a working -- or close to working -- version of your code; we could probably show you how to finish it.