On Wednesday, April 24, 2013 10:57:49 PM UTC-7, Chris Angelico wrote: > On Thu, Apr 25, 2013 at 3:49 PM, llanitedave <llanited...@veawb.coop> wrote: > > > Given that > > > > > > s = some static value > > > i = a value incremented during a loop > > > > > > I'm used to comparing them as > > > > > > if i == s: > > > # some code > > > > > > But for some unknown reason I did a switch > > > > > > if s == i: > > > # same code > > > > > > It didn't seem to make any difference at first glance, so I just got to > > wondering -- > > > > It won't make any difference in any sort of sane code. If there's any > > situation in which == is not reflexive, something seriously nasty is > > going on. > > > > > Is there a standard for comparison order? Is there any kind of performance > > difference? Is there even a tradition for one or the other? Are there any > > gotchas? > > > > It's conventional to compare variables to constants, not constants to > > variables (even in C where there's the possibility of mucking up the > > operator, most people still compare variables to constants). I'd > > normally use "i == s" there, treating s as a constant for the purpose > > of the loop. Unless you're deliberately being poetical, language such > > as "Three is the number thou shalt count" is distinctly abnormal, so > > saying "if (5 == i)" is equally awkward. It's nothing major; mostly > > it's like the algebraic convention of putting the more-known elements > > earlier in a term (eg 2πix - 2 is known, 3.14159.... is mostly known, > > i is imaginary but at least it's constant, and x is unknown). > >
Thanks, Chris. That's kind of along the lines of what I was thinking. Visually, the code just looked wrong, and I figure if for no other reasons than readability it's preferable in the traditional way. It's nice to know, though, that the next time dyslexia strikes it's not necessarily a horrible thing. > > > Do I need to get a hobby? > > > > I thought programming WAS a hobby? > I meant a safer, easier, and more mainstream hobby, like base jumping or motorcycle aerobatics or something. -- http://mail.python.org/mailman/listinfo/python-list
