Le 23/04/19 à 21:48, MRAB a écrit :
On 2019-04-23 19:21, Vincent Vande Vyvre wrote:
Le 23/04/19 à 19:23, Chris Angelico a écrit :
On Wed, Apr 24, 2019 at 3:18 AM Vincent Vande Vyvre
<vincent.vande.vy...@telenet.be> wrote:
Hi,
In a CPython lib I have an _init() method wich take one argument, a
file
name.
char *fname;
if (!PyArg_ParseTuple(args, "s", &fname))
return NULL;
So, if I instanciate my object with a bad argument I've a good error
message:
tif = ImgProc(123)
TypeError: argument 1 must be str, not int
(followed by the traceback)
But if I do:
try:
tif = ImgProc(123)
except Exception as why:
print("Error:", why)
I get just:
Error: <class '_liboqapy.ImgProc'> returned a result with an error set
It looks like there's an internal problem in the C function. Are you
sure it's hitting the PyArg_ParseTuple and then immediately returning
NULL? Post a bit more of your code; this error looks like something is
leaving an error state but then carrying on with the code.
ChrisA
Into the lib:
static int
ImgProc_init(ImgProc *self, PyObject *args, PyObject *kwds)
{
PyObject *tmp;
char *fname;
if (!PyArg_ParseTuple(args, "s", &fname))
return NULL;
tmp = self->src;
self->src = PyUnicode_FromString(fname);
Py_XDECREF(tmp);
return 0;
}
[snip]
That function returns an int.
If PyArg_ParseTuple fails, your function returns NULL, which is cast
to an int, 0.
If PyArg_ParseTuple succeeds, your function returns 0.
Either way, it returns 0.
So how does the caller know whether the function was successful? Does
it check PyErr_Occurred?
No, the caller is in a block try-except for that.
The exact question here is why without a try-except I've the good one
error and not in a try-except.
The /return 0;/ is usual in a /Foo_init()/ function.
Vincent
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