[Tim] >>> ... >>> This is a mess :-) [Nick Coghlan] >> I've been trawling through the code a bit, and I don't think it's as bad as >> all that.
[also Nick, but older & wiser ;-)] > Damn, it really is a mess. . . nb_index returns the Pyssize_t directly, Bingo. It's a /conceptual/ mess. Best I can make out, Travis only cared about sequence slicing (not indexing), and then the machinery got hijacked to become a more general "can you faithfully act like an integer?" thing -- but kept a signature that made sense only for the original slicing use (where clipping is fine). > and a whole heap of the code expects errors to be signalled via returning -1 > before > checking PyErr_Occurred(). > > To get it to work without clipping everywhere, wrap_lenfunc (typeobject.c), > _PyEval_SliceIndex (ceval.c), PyNumber_Index (abstract.c) and sequence_repeat > (abstract.c) all had to be modified to recognize PY_SSIZE_T_MIN and > PY_SSIZE_T_MAX as potential error flags (in order to clear the overflow error > for _PyEval_SliceIndex, and in order to propagate the exception for the other > three). > > And using this approach still means that (2**100).__index__() raises an > OverflowError. > > It would probably be cleaner to change the signature of nb_index to return a > PyObject *, Given that the more-general use is what everyone else either wanted, or simply /assumed/, in the original discussions, I expect it would be, although with the understanding that the PyObject * returned must be NULL (in case of error), or a Python int or long. > and let the code that uses it worry about how (or even whether!) > to convert PyLong results to a Py_ssize_t. A utility function or two could help, like one that converted to Py_ssize_t with clipping, and another that did the same but raised OverflowError if Py_ssize_t isn't big enough (and in the latter case a caller would do the usual business of checking for a -1 return and PyErr_Occurred()).. _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
