John Machin wrote: > thebjorn wrote: [...] > > You give a good argument that the concept of a month is fuzzy > > Sorry, I can't imagine where you got "fuzzy" from. Perhaps you mean > some other word. The concept is capable of being expressed precisely.
and the second to last date in January plus a month is..? > > > Sorry, I don't understand. Why are you speechless? What would I want to > > > use the calendar module for? Apart from the leap() function and the > > > table of days in a month, the calendar module doesn't have any of the > > > functionality that one would expect in a general-purpose date class. > > > > Well, I thought replacing a 4 line function with 31 lines, 13 of which > > duplicated functionality in the standard library was overkill. > > I think you missed the point that the lines I quoted were straight out > of a self-contained library that existed (in C as well as Python) way > before the datetime module was a gleam in Fred & the timbot's eyes. I'm guessing you missed that I was looking for a method in the stdlib to do this, and failing that an idiomatic solution... > Even if I had noticed a leap year function in the calendar module, I > would probably not have used it. The Python version of the module was > just a stopgap while I fiddled with getting a C extension going. The C > leap year function doesn't have any of that modulo stuff in it. I'm sure it doesn't. You might want to look at the assembly your C compiler produces for a modulo-power-of-2 operation... > > I came up with this yesterday which seems sufficient? > > > > def yeardiff(a, b): > > y = a.year - b.year > > if (a.month, a.day) < (b.month, b.day): # tuple comparison > > y -= 1 > > return y > > At least it doesn't blow up when b is leapyear-02-29. It just gives the > wrong answer when a is nonleapyear-02-28. E.g. it gives 0 years > difference from 1992-02-29 to 1993-02-28 instead of 1. I believe you're mistaken (but feel free to correct me), my grandmother is born on Feb 29 and a quick call to my dad verified that they celebrated it the day after the 28th (unless Mar 1 was a Monday ;-). http://timeanddate.com/date/duration.html also seem to agree with my current understanding, just as a datapoint if nothing else. -- bjorn -- http://mail.python.org/mailman/listinfo/python-list
