When to free memory for C wrapper?

Java and Swing codecraig at gmail.com
Thu Oct 13 15:47:06 CEST 2005

One other thing, I was reading about Py_DECREF...and I see it says

"A safe approach is to always use the generic operations (functions
whose name begins with "PyObject_", "PyNumber_", "PySequence_" or
"PyMapping_"). These operations always increment the reference count of
the object they return. This leaves the caller with the responsibility
to call Py_DECREF() when they are done with the result; this soon
becomes second nature."
URL: http://www.python.org/doc/api/refcounts.html

So does that mean before my C wrapper function exits, or returns I
should Py_DECREF any PyObject's I have?  For example, in my previous
post in this thread..I would have to Py_DECREF(data) right?

What if in my wrapper I had

static PyObject *wrap_doStuff(...) {
    PyObject *pyResult;


    pyResult = PyString_FromString(...);

   return pyResult;

Is PyResult going to be de-referenced or handled automaticlly by python
in some way?  Or, do I need to somehow call Py_DECREF(pyResult)
somewhere..if so, where/when?


Java and Swing wrote:
> I have been posting lately about writing a C wrapper so Python can
> access my C functions.
> In my wrapper function I have something like...
> static PyObject *wrap_doStuff(PyObject *self, PyObject *args) {
>     PyObject *data;
>     char *result;
>     long *d;
>     PyArg_ParseTuple(args, "O:wrap_doStuff", &data);
>     d = get_long_array(data);
>     result = doStuff(d);
>     return PyString_FromString(result);
> }
> Now, do I need to use PyMem_Free to free up the "PyObject *data"?
> Thanks.

More information about the Python-list mailing list