[Python-Dev] Inplace operations for PyLong objects

[Manciu, Catalin Gabriel]

> My question is -- how can the interpreter know if it can alter what is 
> supposed to be an immutable in-place? If it's used only internally to a 
> function, the it would be safe, but how to know that?

> -CHB

You can just check the reference count of your object, it's a member of the
PyObject structure which every CPython object contains: ob_refcnt. This will
indicate if your object is referenced by other Python variables or by Python
containers such as lists, tuples, dicts, sets etc.