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). > Do I need to get a hobby? I thought programming WAS a hobby? ChrisA -- http://mail.python.org/mailman/listinfo/python-list
