The problem with delattr (and thus PyObject_DelAttr) arises when you define a __delattr__ method on your class. There is not easy way to then call back into the "normal" python delattr semantics, except by doing object.__delattr__ (which is not optimized by Cython).
Futher, calling PyObject_GenericSetattr(obj, name, NULL) appears to be the proper use, given that it properly follows the descriptor chain and will call __delete__ if obj.name is a descriptor. I would argue that there should be at least some way to pass a NULL pointer in Cython where a PyObject* is expected. On Sun, Feb 13, 2011 at 3:31 PM, Greg Ewing <greg.ew...@canterbury.ac.nz>wrote: > Chris Colbert wrote: > >> I have cython file which is using PyObject_GenericSetAttr >> Now in my script I am using that function to generically delete an >> attribute by passing a NULL as the last value (this is proper way to trigger >> a generic delattr in the Python c-api) >> > > I would have thought the proper way to do that was to use > PyObject_DelAttr, which Pyrex exposes as delattr(). > > I don't think PyObject_GenericSetAttr is even meant to be > called directly -- it's intended for filling the tp_setattr > slot of type objects. > > > This causes a segfault because the NULL is getting increfed via Py_INCREF >> instead of Py_XINCREF. >> > > I would recommend against trying to "fix" this. You got > away with it before because you happened to be passing the > NULL value directly to a function which is expecting it. > But casting NULL to an object reference is not something > that should be encouraged, because in any other context it > would quickly lead to disaster. > > -- > Greg >
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