Brian van den Broek wrote:
> Can it then be further (truly :-) ) said that
>
> if False:
> # thousands of lines of code here
>
> would effect the structure of the function object's bytecode, but not
> its behaviour when run? Or, at most, would cause a performance effect
> due to the bytecode being bloated by thousands of line's worth of code
> that would never get executed?
>
Yes, but that purely an implementation detail.
if 0:
# thousands of lines of code here
has no effect at all on the bytecode, it it optimised out entirely. 'if
False:' is not optimised out in Python 2.4 or earlier, but might be in
later versions.
Now, to really get your brain hurting, see what this one does:
def hurts_my_brain(v):
if 0: # unlike Steve's eg, ensuring that the
global x # nested block is never hit at runtime
x = v
I'll give you a clue, it's not the same as your:
def hurts_my_brain(v):
if False: # unlike Steve's eg, ensuring that the
global x # nested block is never hit at runtime
x = v
So the global statement is a wart which isn't executed at runtime, but
behaves differently when the bytecode it doesn't generate is optimised out.
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