SystemError: new style getargs format but argument is not a tuple

[zefciu]

I am trying to embed a c function in my python script for a first time.
When I try to call it I get an error

SystemError: new style getargs format but argument is not a tuple

Guido said on some mailing list, that it is probably an effect of the
lack of METH_VARARGS in the functions' array, but it's ok in my source
code. Here is the full code:

#include <python2.4/Python.h>

static PyObject * mandelpixel(PyO bject *self, PyObject *args)
{
double z_real = 0, z_imag = 0, z_real2 = 0, z_imag2 = 0, c_real,
c_imag, bailoutsquare;
int iteration_numbe r;
register int i;
PyObject coord;
if (!PyArg_ParseTu ple(args, "Oid", &coord, &iteration_numb er,
&bailoutsquare) )
return NULL;
if (!PyArg_ParseTu ple(&coord, "dd", &c_real, &c_imag))
return NULL;

for(i = 1; i <= iteration_numbe r; i++)
{
z_imag = 2 * z_real * z_imag + c_imag;
z_real = z_real2 - z_imag2 + c_real;
z_real2 = z_real * z_real;
z_imag2 = z_imag * z_imag;
if (z_real2 + z_imag2 bailoutsquare)
return Py_BuildValue(" i", i);
}
return Py_BuildValue(" i", 0);
}

static PyMethodDef MandelcMethods[] =
{
{
"mandelpixe l", mandelpixel, METH_VARARGS, "check the pixel for
Mandelbrot set"
},
{
NULL, NULL, 0, NULL
}
};

PyMODINIT_FUNC initmandelc(voi d)
{
(void) Py_InitModule ("mandelc", MandelcMethods) ;
}

int main(int argc, char **argv)
{
Py_SetProgramNa me(argv[0]);
Py_Initialize() ;
initmandelc();
return 0;
}

Greets
zefciu

[Thinker]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

zefciu wrote:

I am trying to embed a c function in my python script for a first
time. When I try to call it I get an error

SystemError: new style getargs format but argument is not a tuple

Guido said on some mailing list, that it is probably an effect of
the lack of METH_VARARGS in the functions' array, but it's ok in my
source code. Here is the full code:

#include <python2.4/Python.h>

static PyObject * mandelpixel(PyO bject *self, PyObject *args) {
double z_real = 0, z_imag = 0, z_real2 = 0, z_imag2 = 0, c_real,
c_imag, bailoutsquare; int iteration_numbe r; register int i;
PyObject coord; if (!PyArg_ParseTu ple(args, "Oid", &coord,
&iteration_numb er, &bailoutsquare) ) return NULL; if
(!PyArg_ParseTu ple(&coord, "dd", &c_real, &c_imag)) return NULL;

Is coord always tuple?

- --
Thinker Li - th*****@branda. to th********@gmai l.com
http://heaven.branda.to/~thinker/GinGin_CGI.py
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (FreeBSD)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFF4wQB1LD UVnWfY8gRAtWsAK CavY85KUtoppRSj 0uQTeVnmLu5UwCg yfk1
0c5fkRgKaejDja1 YWdKkaTg=
=vMjd
-----END PGP SIGNATURE-----

[zefciu]

Thinker wrote:

zefciu wrote:

>>I am trying to embed a c function in my python script for a first
time. When I try to call it I get an error

SystemError : new style getargs format but argument is not a tuple

Guido said on some mailing list, that it is probably an effect of
the lack of METH_VARARGS in the functions' array, but it's ok in my
source code. Here is the full code:

Is coord always tuple?

Yes it is. The script launches it with tuple and two numeric arguments.
On the other hand when I try it in interactive mode with
mandelpixel((1, 1), 1, 1) it segfaults, which I completely don't understand.

zefciu

[Thinker]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

zefciu wrote:

I am trying to embed a c function in my python script for a first
time. When I try to call it I get an error

SystemError: new style getargs format but argument is not a tuple

Guido said on some mailing list, that it is probably an effect of
the lack of METH_VARARGS in the functions' array, but it's ok in my
source code. Here is the full code:

#include <python2.4/Python.h>

static PyObject * mandelpixel(PyO bject *self, PyObject *args) {
double z_real = 0, z_imag = 0, z_real2 = 0, z_imag2 = 0, c_real,
c_imag, bailoutsquare; int iteration_numbe r; register int i;
PyObject coord;

It should be "PyObject *coord;" .
Maybe, it is what is wrong with your program!

- --
Thinker Li - th*****@branda. to th********@gmai l.com
http://heaven.branda.to/~thinker/GinGin_CGI.py
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (FreeBSD)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFF4xDz1LD UVnWfY8gRAmAAAJ 9FJPqGyeI0Inxrc vdNXHtGMXWK1wCg 570r
z3hcYDsjmqRp4Bn pEFjbDy0=
=REQM
-----END PGP SIGNATURE-----

[zefciu]

Thinker wrote:

It should be "PyObject *coord;" .
Maybe, it is what is wrong with your program!

Should it? The gcc shows me a warning then:

warning: 'coord' is used uninitialized in this function

and during the execution I get the same error *plus* a segfault.

zefciu

[Thinker]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

zefciu wrote:

Thinker wrote:

>It should be "PyObject *coord;" . Maybe, it is what is wrong with
your program!

Should it? The gcc shows me a warning then:

warning: 'coord' is used uninitialized in this function

and during the execution I get the same error *plus* a segfault.

zefciu

Yes! Please refer http://docs.python.org/api/arg-parsing.html#l2h-210
And your second PyArg_ParseTupl e() call, should not make a reference
on coord.
It should be PyArg_ParseTupl e(coord, ...) since you declare coord as a
pointer.
You can add some printf() to throw out messages to make sure where the
program stop at.
If you can compile the module with debug information and use gdb to
backtrace dump file,
it would be useful.

- --
Thinker Li - th*****@branda. to th********@gmai l.com
http://heaven.branda.to/~thinker/GinGin_CGI.py
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (FreeBSD)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFF4xaG1LD UVnWfY8gRAsW7AK C7D3oZ8p8iWVFcB vkiVwMSrG1oNwCg 36ym
e1Fa0AO3KzSD5Fc Ys0LK7P4=
=kYLW
-----END PGP SIGNATURE-----

[zefciu]

Thinker wrote:

You can add some printf() to throw out messages to make sure where the
program stop at.
If you can compile the module with debug information and use gdb to
backtrace dump file,
it would be useful.

Did it. The arguments are parsed, but the coord tuple isn't. But can
PyArg_ParseTupl e be used to tuples other than function arguments? If
not, what should I use?

zefciu

[Thinker]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

zefciu wrote:

Thinker wrote:

>You can add some printf() to throw out messages to make sure
where the program stop at. If you can compile the module with
debug information and use gdb to backtrace dump file, it would be
useful.

Did it. The arguments are parsed, but the coord tuple isn't. But
can PyArg_ParseTupl e be used to tuples other than function
arguments? If not, what should I use?

Since PyArg_ParseTupl e() is supposed to parse arguments, I recommand you
to use PyTuple_GetItem () or PyTuple_GET_ITE M(). You can find more
functions
at http://docs.python.org/api/genindex.html .

- --
Thinker Li - th*****@branda. to th********@gmai l.com
http://heaven.branda.to/~thinker/GinGin_CGI.py
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (FreeBSD)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFF4xyq1LD UVnWfY8gRAilNAK DFTKwahXpuxFImh R57Yw5efAGP1wCf R/qU
o774g2YB5gMBLrU a9YltDSQ=
=/tWC
-----END PGP SIGNATURE-----

[zefciu]

Thinker wrote:

Since PyArg_ParseTupl e() is supposed to parse arguments, I recommand you
to use PyTuple_GetItem () or PyTuple_GET_ITE M().

Ok. Now I do it this way:

c_real = PyFloat_AsDoubl e(PyTuple_GetIt em(coord,0));
c_imag = PyFloat_AsDoubl e(PyTuple_GetIt em(coord,1));

And it worked... once. The problem is really funny - in the interactive
the function fails every second time.

>>mandelpixel(( 1.5, 1.5), 9, 2.2)

args parsed
coord parsed
ii3

>>mandelpixel(( 1.5, 1.5), 9, 2.2)

TypeError: bad argument type for built-in operation

>>mandelpixel(( 1.5, 1.5), 9, 2.2)

args parsed
coord parsed
ii3

>>mandelpixel(( 1.5, 1.5), 9, 2.2)

TypeError: bad argument type for built-in operation

etcaetera.... (the "args parsed" "coord parsed" and "i" are effect of
printfs in the code, as you see when it fails, it doesn't even manage to
parse the arguments.

zefciu

[Thinker]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

zefciu wrote:

Thinker wrote:

>Since PyArg_ParseTupl e() is supposed to parse arguments, I
recommand you to use PyTuple_GetItem () or PyTuple_GET_ITE M().

Ok. Now I do it this way:

c_real = PyFloat_AsDoubl e(PyTuple_GetIt em(coord,0)); c_imag =
PyFloat_AsDoubl e(PyTuple_GetIt em(coord,1));

And it worked... once. The problem is really funny - in the
interactive the function fails every second time.

>>>mandelpixel( (1.5, 1.5), 9, 2.2)

args parsed coord parsed ii3

>>>mandelpixel( (1.5, 1.5), 9, 2.2)

TypeError: bad argument type for built-in operation

I guess it is caused by ill handling reference count of coord.
You should call Py_INCREF() to get a reference since it is borrowed
from PyArg_ParseTupl e().
You can find more information at http://docs.python.org/ext/refcounts.html

- --
Thinker Li - th*****@branda. to th********@gmai l.com
http://heaven.branda.to/~thinker/GinGin_CGI.py
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (FreeBSD)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFF4yuP1LD UVnWfY8gRAqOmAJ 0SaIwpnRk/GZYm2Z5nnC7xH7E YKwCgjz8o
0Z/S7i5PULQMeAFI7U/Cy5I=
=4C3l
-----END PGP SIGNATURE-----