C api question and determining PyObject type
lallous
I have an a class defined as:
class __object(object):
pass
Now, I call a C function that takes a PyObject* and checks its type:
if (PyString_Check(obj)) ...
if (PySequence_Check(obj)) ....
Before doing the check, I print the passed object with PyObject_Str() and
get:
passed object: <__main__.__object object at 0x040E4050>
However, the C code returns true on the:
if (PySequence_Check(obj)) ....
Why? That is not a sequence?
Please advise.
--
Elias
lallous
class __object(object):
def __getitem__(self, idx):
return getattr(self, idx)
Anyway, now I check like this:
bool PyIsSequenceType(PyObject *obj)
{
if (!PySequence_Check(obj))
return false;
Py_ssize_t sz = PySequence_Size(obj);
if (sz == -1 || PyErr_Occurred() != NULL)
{
PyErr_Clear();
return false;
}
return true;
}
I don't like it, any other suggestions?
--
Elias
"lallous" <lal...@lgwm.org> wrote in message news:hdr80a$vsg$1...@aioe.org...
Gabriel Genellina
> Actually, the object class is defined as:
> class __object(object):
> def __getitem__(self, idx):
> return getattr(self, idx)
>
> Anyway, now I check like this:
>
> bool PyIsSequenceType(PyObject *obj)
> {
> if (!PySequence_Check(obj))
> return false;
> Py_ssize_t sz = PySequence_Size(obj);
> if (sz == -1 || PyErr_Occurred() != NULL)
> {
> PyErr_Clear();
> return false;
> }
> return true;
> }
>
> I don't like it, any other suggestions?
Yes: find another name for the "thing" you're checking for. It's not the
same as a "sequence" in the Python sense.
Perhaps you want to consider your type a mapping? Sequences and mappings
have a lot in common (mappings have length too.) In C you have separate
slots tp_as_sequence, tp_as_mapping; but in Python code, __getitem__ is
used for both meanings (and goes into both set of pointers.) tp_as_mapping
takes precedence over tp_as_sequence.
--
Gabriel Genellina
Gabriel Genellina
> Actually, the object class is defined as:
> class __object(object):
> def __getitem__(self, idx):
> return getattr(self, idx)
>
> Anyway, now I check like this:
>
> bool PyIsSequenceType(PyObject *obj)
> {
> if (!PySequence_Check(obj))
> return false;
> Py_ssize_t sz = PySequence_Size(obj);
> if (sz == -1 || PyErr_Occurred() != NULL)
> {
> PyErr_Clear();
> return false;
> }
> return true;
> }
>
> I don't like it, any other suggestions?
Yes: find another name for the "thing" you're checking for. It's not the