Style question for conditional execution
arnodel at gmail.com
Wed Nov 24 21:25:19 CET 2010
Gerald Britton <gerald.britton at gmail.com> writes:
> Writing in Python gives me the luxury of choosing different paradigms
> for similar operations. Lately I've been thinking about a minor
> detail that peaked my interest and am curious what others think:
> Say that I have some function "f" that I will execute if some variable
> "v" evaluates true. Using a classical procedural approach, I might
> if v:
> I might, however, think more in a functional-programming direction.
> Then I might write:
> v and f()
> Interestingly, this second expression compiles smaller (though only by
> a little) in both Python 2.6 and 3.1, which I currently have
> installed. If I had thousands of such expressions, I could boast
> about a measurable difference but practically speaking, it is not
> What I _am_ interested in, however, is feedback from a style perspective.
> What do the rest of you think about this?
> Have you used the second approach and, if so, what was your motivation?
> Is there a good/bad reason to choose one over the other?
I would use the if: form every time but it's interesting that the
"JUMP_FORWARD 0" instruction below doesn't get optimised away.
If it did, both forms would be the same compiled lengths.
>>> def g():
... if v: f()
2 0 LOAD_GLOBAL 0 (v)
3 POP_JUMP_IF_FALSE 16
6 LOAD_GLOBAL 1 (f)
9 CALL_FUNCTION 0
13 JUMP_FORWARD 0 (to 16)
>> 16 LOAD_CONST 0 (None)
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