[Brian van den Broek]
<SNIP setup of how I was wondering if I was making things too complicated with:>
import datetime def is_leap_year(year): '''-> boolean
Returns True or False as year is, or is not, a leap year. ''' is_leap = True try: datetime.date(year, 2, 29) except ValueError: is_leap = False return is_leap
Kent Johnson said unto the world upon 2004-12-15 20:16: > I would write > def is_leap_year(year): > try: > datetime.date(year, 2, 29) > return True > except ValueError: > return False
Not an adherent of the "only one exit point" doctrine then, hey? I spent a while a few weeks ago with a bug in a function that happened because I'd not noticed that I had two return statements, so I'm leery of this at the moment. (I concede if the function was long enough to hide that from me, it was probably too long.) I also like the conceptual purity of one way in and one way out. But, in my code above, that is indeed purchased at the cost of the ugly and a bit anomalous assignment of True.
Tim Peters said unto the world upon 2004-12-15 23:14:
So far as leap years go, the obvious difference is that February has 29 days in leap years, but only 28 otherwise. You exploit that above by checking whether trying to construct "February 29th" raises an exception. That's fine. At least an equally good way is to note that the difference between March 1 and Februrary 28 is 2 days only in a leap year, so:
from datetime import date, timedelta def isleap(year): return (date(3, 1, year) - date(2, 28, year)).days == 2
<SNIP 2 other ways of similar style>
def isleap(year): return (date(year+1, 1, 1) - date(year, 1, 1)).days == 366
IOW, if you can think of one way to do it with a Boolean expression, it's common to think of more. And, of course, that's the kind of practice that makes it feel natural, over time.
4 ways all shorter than mine; well, thank goodness I wasn't asking about this in Perl ;-)
Thanks for the examples. Pretty and concise often go together, but they seem not to be want to be seen with me. Implausible though my posting history may make it sound, I've done a fair bit of work in set theory and math. logic. While my proofs work, they are almost never pretty or concise. Seems like my code has similar tendencies. I appreciate the pushes in a better direction.
At least I won't be stuck for things to do when it comes time to refactor!
Thanks to both,
Brian vdB _______________________________________________ Tutor maillist - [EMAIL PROTECTED] http://mail.python.org/mailman/listinfo/tutor
