On Thu, Mar 9, 2017, at 18:43, Erik wrote: > Hi. > > I'm looking at stuff proposed over on Python-Ideas, and I'd appreciate > some pointers as to the basics of how C-level objects are generally > compared in Python 3. > > The issue is related to the performance of PyObject_RichCompare. I got > to the point where I was trying to work out what was the _alternative_ > to RichCompare. If a comparison is not "rich", then what is it? There's > a tp_richcompare slot in the type structure, but I haven't noticed > anything else obvious for simple comparison (In 2.x days - which I have > more experience with - __cmp__ was a thing which now seems to be gone. I > understand the Python-level changes with sort(..., key=foo) but I've not > looked at the underlying C implementation until now).
In 2.x the C version of __cmp__ was tp_compare (and it existed even in python 0.9.1, which had neither dunder methods nor tp_richcompare). I assume that the "rich compare" name was retained in Python 3 for the same reason that other names like PyLongObject, PyUnicodeObject were (not PyStringObject, though, presumably because they don't want people to unintentionally create a bytes-only API as a result of a lazy porting process). Maybe Python 4000 can alias it to tp_compare (PyIntObject, PyStringObject) and Python 5000 can get rid of the current names. It's "rich" because it knows which of the object-level methods (less than, greater than, etc) is being called, whereas tp_compare/__cmp__ did not. _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
