On 2014年02月18日 14:11, MRAB wrote:
tuple's rich comparison uses PyObject_RichCompareBool(x, y, Py_EQ) to find the first pair of items that is unequal. Then it will test the order of any remaining elements.On 2014年02月18日 13:48, Serhiy Storchaka wrote:18.02.14 10:10, Paul Moore написав(ла):Or alternatively, a "default on None" function - Oracle SQL calls this nvl, so I will too:def nvl(x, dflt): return dflt if x is None else x results = sorted(invoices, key=lambda x: nvl(x.duedate, datetime(MINYEAR,1,1))Or, as was proposed above: results = sorted(invoices, key=lambda x: (x.duedate is not None, x.duedate))That makes me wonder. Why is: None < None unorderable and not False but: (None, ) < (None, ) orderable?
http://hg.python.org/cpython/file/79e5bb0d9b8e/Objects/tupleobject.c#l591 PyObject_RichCompareBool(x, y, Py_EQ) treats identical objects as equal. http://hg.python.org/cpython/file/79e5bb0d9b8e/Objects/object.c#l716 -- Robert Kern "I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco _______________________________________________ Python-Dev mailing list [email protected] https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com