On Tue, Nov 02, 2010 at 05:28:43PM +0900, Stephen J. Turnbull wrote: > C. Titus Brown writes: > > > p.s. Seriously? I can accept that there's a rational minimalist argument > > for this "feature", > > It is a feature, even if you aren't gonna need it. I want it.<wink> > > Many programmers do know that sets are partially ordered by inclusion, > preordered by size, and (in Python) totally ordered by memory address. > There's nothing wrong with not knowing that -- these are rather > abstract mathematical concepts. But it's very useful that sorted() or > .sort() use <=, and it's very useful that Python so often obeys simple > consistent rules, and it would be quite confusing to those who do > understand that "in Python the set type is partially ordered by > inclusion" if sorted() used some other relation to order collections > of sets. > > It's not so hard to change this:
[ ... ] > If there were an obvious way to compare sets for use in sorting, that > way would very likely be the most useful definition for <=, too. But > there isn't, really (it's pretty obvious that comparing memory > addresses is implausible, but otherwise, there are lots of candidates > that are at least sometimes useful). Do you think otherwise? If so, > what do you propose for the OOWTDI of sorting a collection of sets? I don't have one... > > but arguing that it's somehow the responsibility of a programmer to > > *expect* this seems kind of whack. > > I don't quite agree that everyone should "expect exactly the > implemented behavior", but I do think it's a Python *programmer's* > responsibility to refrain from expecting something else in this case. ...but, as someone who has to figure out how to teach stuff to CSE undergrads (and biology grads) I hate the statement "...any programmer should expect this..." because (unless you're going to disqualify a huge swathe of people from being programmers) it's *just not true*. I don't expect Python to cater to the lowest common denominator but we should be mindful of our audience, too. I think Python has a great advantage in not being too surprising much of the time, which helps quite a bit with learning. I hope people keep that in mind for future features. cheers, --t -- C. Titus Brown, c...@msu.edu _______________________________________________ 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