甜瓜 wrote: > Howdy, > I wonder whether python compiler does basic optimizations to .py. > Eg: > t = self.a.b > t.c = ... > t.d = ... > .vs. > self.a.b.c = ... > self.a.b.d = ... > which one is more effective? Since each dot invokes a hash table lookup, > it may be time consuming. If the compiler can do expression folding, then > no manual folding is needed.
It can't do that because of no guarantee can be made that self.a has no side-effects, and consequently doesn't do it. > Again, how about contant calculation? > Eg: > a = 1 + 2 > .vs. > a = 3 > which one is more effective? Does the compiler calculate the result at > compile time? How about constant spreading? Algebraic optimizations aren't done AFAIK - and it's debatable if the mu-secs saved by that would be worth the effort, as if *they* matter, you obviously are in number-crunching mode and should resort to libs such as Numpy to do your work. Diez -- http://mail.python.org/mailman/listinfo/python-list
