Python/C API - PyArg_ParseTuple problem ?

Michael Hudson mwh at python.net
Fri Aug 22 20:23:28 CEST 2003


"Poire Williams" <poire.williams at nomore.org> writes:

> Hi, everybody.
> 
> I'm writing a Python binding for a C++ library and I just found something
> that puzzles me.

[snippety]

> If I do this:
> 
> >> s = 'hi'
> >> t = NewType(0, 42, s)
> 
> everything is well... 

Even after a 'del s'?

> Moreover, if I change my C code to something like
> this:
> 
> if (!PyArg_ParseTuple(args, "ii|O", &a, &b, &o)
>     return NULL;
> s = PyString_AsString(o);
> 
> everything's fine again, in both cases...
> 
> I guess it's some kind of twisted reference count thing, and I'm still
> trying to get some minimal C code to reproduce this. Meanwhile, does
> anybody have a clue ?
> 
> Thanks in advance.
> 
> Precisions: I'm running Python 2.2.3 on Linux, and I don't free() the
> buffer retrieved via PyArg_ParseTuple or PyString_AsString :)

No, but I bet you're stuffing it into your data structure somewhere
along the line.  I think you need to copy the string data.

Cheers,
mwh

-- 
  In that case I suggest that to get the correct image you look at
  the screen from inside the monitor whilst standing on your head.  
               -- James Bonfield, http://www.ioccc.org/2000/rince.hint




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