Setting a C-structure from Python

[Armin Steinhoff]

In article <396F6449.F2E63F85 at seatech.fau.edu>, Benoit says...
>
>
>Armin wrote:
>--------------------------------------------------------------
>
> I have changed your code in the following way:
>
> static PyObject * test_setstruct(PyObject * self, PyObject * args) {
> //PyObject * string_from_python;
>
> char * string_from_python;
> int len;
>
> // if (!PyArg_ParseTuple(args,"S",&string_from_python)) return NULL;
> if (!PyArg_ParseTuple(args,"s#",&string_from_python, &len)) return NULL;
>
> // example= (examplestruct *) PyString_AsString(string_from_python);
>example= (examplestruct *) string_from_python;
>
> // Py_DECREF(string_from_python);
> print_struct();
>
> Py_INCREF(Py_None);
> return Py_None;
> }
> ----------------------------------------------------
>
>Ok it works too! You convert the PythonString in a C string representation
>right away with PyArgs_ParseTuple.
>
>
>
>Now, I changed the test_getstruct function in the same way..
>
>static PyObject * test_getstruct(PyObject * self, PyObject * args)
>{
> if (!PyArg_ParseTuple(args,"")) return NULL;
                             ^^ ???

> return Py_BuildValue("s",(char *)exampleptr);
                        ^             ^
                       "s#"      exampleptr, len);

 ... then it should work :-)

Greetings

Armin

BTW ... remove in the qnx_send procedure the Py_BuildValue() call ... its
garbage. ( 'qnxmodule' )


>}
>
>
>Yes.. it was too easy : it doesn't work :
>    Traceback (innermost last):
>      File "<stdin>", line 1, in ?
>      File
>"//1/old_home/bdupire/Alpha/morpheus/Python-1.5.2/Lib/my_prog/structure.py",
>line 24, in ?
>       a =struct.unpack(fmt,rec)
>struct.error: unpack str size does not match format
>
>So my question is the following: how to tell Py_BuildValue about the size of
>the structure and the number of bytes to grab ?
>