[PYTHON MATRIX-SIG] C API questions

[Konrad Hinsen]

> The one part about this discussion I didn't follow was the part about trying
> to make sure Python does not keep a reference to your compiled object. That
> is probably impossible what with traceback stacks and all. Or maybe I didn't
> get it. 

But the traceback stack does not keep its references forever, I hope.
Is there maybe a way to force it to give up a certain reference?

> If you do use PyArray_FromDimsAndData you should just follow the normal
> Python rules for reference counting in your extensions and since the count
> started out at 1 it will never get deleted. But if the pointer points to
> something that might not be there later, this is the wrong Python object to
> model it, IMHO. 

But what other choice do I have? I want to define a general C-level
interface to some of my code, which might actually be Python code.
So I must construct a C wrapper around the Python functions. But a
C function can't make any assumptions about the existence of its
actual parameters after it returns. It might look like:

   double *x = malloc(n*sizeof(double));
   do_some_calculation(x, n);
   free(x);

with

   void do_some_calculation(double *x, int n)
   {
      PyArrayObject *a = PyArray_FromDimsAndData(.., x, n, ..);
      /* call Python function working on a */
   }

In that case I must make sure that no access to the memory pointed
to by x can occur after my C wrapper exits.

Konrad.
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Konrad Hinsen                          | E-Mail: hinsen@ibs.ibs.fr
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