On Fri, 17 Apr 2009 12:10:59 pm Tennessee Leeuwenburg wrote: > Actually, that's a point. > > If its' the 31st of Jan, then +1 monthdelta will be 28 Feb and > another +1 will be 28 March whereas 31st Jan +2 monthdeltas will be > 31 March. > > That's the kind of thing which really needs to be documented, or I > think people really will make mistakes.
It might be worth noting as an aside, but it should be obvious in the same way that string concatenation is different from numerical addition: 1 + 2 = 2 + 1 '1' + '2' != '2' + '1' > For example, should a monthdelta include a goal-day so that the > example above would go 31 Jan / 28 Feb / 31 March? No, that just adds complexity. Consider floating point addition. If you want to step through a loop while doing addition, you need to be aware of round-off error: >>> x = 0.0 >>> step = 0.001 >>> for i in xrange(1000): ... x += step ... >>> x 1.0000000000000007 The solution isn't to add a "goal" to the plus operator, but to fix your code to use a better algorithm: >>> y = 0.0 >>> for i in xrange(1, 1001): ... y = i*step ... >>> y 1.0 Same with monthdelta. -- Steven D'Aprano _______________________________________________ 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
