Passing a memory address (pointer) to an extension?

[Thomas Heller]

Philip Semanchuk schrieb:
> I'm writing a Python extension in C that wraps a function which takes  
> a void * as a parameter. (The function is shmat() which attaches a  
> chunk of shared memory to the process at the address supplied by the  
> caller.) I would like to expose this function to Python, but I don't  
> know how to define the interface.
> 
> Specifically, when calling PyArg_ParseTuple(), what letter should I  
> use to represent the pointer in the format string? The best idea I can  
> come up with is to use a long and then cast it to a void *, but  
> assuming that a long is big enough to store a void * is a shaky  
> assumption. I could use a long long (technically still risky, but  
> practically probably OK) but I'm not sure how widespread long longs are.

I suggest "O!" and a converter function calling PyLong_AsVoidPtr().

Thomas