Python - how to check if weak reference is still available

Question

Hi all,

I am passing some weakrefs from Python into C++ class, but C++ destructors are actively trying to access the ref when the real object is already dead, obviously it crashes...

Is there any Python C/API approach to find out if Python reference is still alive or any other known workaround for this ?

Thanks

Answer 1

From Python C API documentation:

PyObject* PyWeakref_GetObject(PyObject *ref)
Return value: Borrowed reference.
Return the referenced object from a weak reference, ref. If the referent is no longer live, returns None. New in version 2.2.

Answer 2

If you call PyWeakref_GetObject on the weak reference it should return either Py_None or NULL, I forget which. But you should check if it's returning one of those and that will tell you that the referenced object is no longer alive.