On Sun, 3 Oct 2010 01:17:39 am bob gailer wrote: > I ran dis on a for loop and the equivalent comprehension. > > I was surprised to see almost identical code. > > I had assumed (and now wish for) that a comprehension would be a > primitive written in C and thus much faster!
How could it be? A list comp is syntactic sugar. It needs to perform the same steps as a for-loop, and call an arbitrary Python expression. It's not like map() that takes a function object. Unless you had a separate primitive for every imaginable Python expression -- which is impossible -- list comps need to generate relatively similar code to for-loops because they do relatively similar things. Besides, in recent versions of Python the speed of for-loops is quite good. The bottleneck is rarely the loop itself, but the work you do in the loop or the size of the loop. -- Steven D'Aprano _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
