How to catch a usefull error message ?
Vincent Vande Vyvre
vincent.vande.vyvre at telenet.be
Tue Apr 23 14:21:17 EDT 2019
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.vyvre at 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;
}
If i do:
try:
tif = ImgProc(123)
except Exception as why:
print(sys.exc_info())
raise
I get:
(<class 'SystemError'>, SystemError("<class '_liboqapy.ImgProc'>
returned a result with an error set",), <traceback object at
0x7f3bcac748c8>)
TypeError: argument 1 must be str, not int
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/home/vincent/oqapy-3/trunk/filters/ui_lenscorrection.py", line
104, in on_main_cursor_changed
self.prepare_preview_process()
File "/home/vincent/oqapy-3/trunk/filters/ui_lenscorrection.py", line
137, in prepare_preview_process
self.main.process_on_preview(params)
File "/home/vincent/oqapy-3/trunk/filters/lenscorrection.py", line
56, in process_on_preview
tif = ImgProc(123)
SystemError: <class '_liboqapy.ImgProc'> returned a result with an error set
--------------------------------------------------------------------------------
Why a SystemError ?
I'm using Python 3.6.7 and 3.7.3
Vincent
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