Embedding: Problem with CallObject

Bernhard Herzog bh at intevation.de
Thu Jun 14 11:23:51 CEST 2001


"James Turner" <jamwt at jamwt.com> writes:

> Hello.
> 
> I'm just starting to play with embedding Python in C, and I'm getting a
> huge headache from trying to figure out what's wrong with my code here:
> 
> --test.c--
> #include <Python.h>
> 
> int main(int argc, char** argv)
> {
>     PyObject *str,*mod,*flist,*func,*args;
>     Py_Initialize();
>     str = PyString_FromString("anything");
> 
>     /*Import mod */
>     mod = PyImport_Import(PyString_FromString("one") );

This is a memory leak, because PyString_FromString returns a new
reference. It would probably be easier to use PyImport_ImportModule
because it takes a C string as argument and not a Python string object.

> 
>     flist = PyModule_GetDict(mod);
>     func = PyDict_GetItemString(flist,PyString_FromString("out"));

PyDict_GetItemString takes a char* as the second argument, not a string
object, so it should be:
func = PyDict_GetItemString(flist, "out");

Your version most likely returns NULL causing the segfault later.

>     args = PyTuple_New(1);
>     PyTuple_SetItem(args, 0,str);
> 
>     /* FAILS HERE!! */
>     PyObject_CallObject(func,args);

You should check the return value of PyObject_CallObject and DECREF it.

>     Py_XDECREF(flist);
>     Py_XDECREF(func);

Don't DECREF func because it's a borrowed reference. Likewise for flist.

>     Py_XDECREF(args);
>     Py_XDECREF(mod);
>     Py_XDECREF(str);
> 
>     Py_Finalize();
>     return 0;
> }


HTH,

   Bernhard
-- 
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