Steven D'Aprano <[EMAIL PROTECTED]> writes:
> On Sat, 04 Oct 2008 17:07:14 +0200, Martin Geisler wrote:
>
>> A somewhat related question: do I pay a performance penalty when I
>> let a function define an inner function like this:
>>
>> def foo():
>>
>> def bar()
>> ...
>>
>> bar()
>>
>> compared to just defining it once outside:
>>
>> def bar():
>> ...
>>
>> def foo():
>> ...
>> bar()
>>
>> I'm thinking that each execution of the first foo could spend a
>> little time defining a new bar each time, or is that not how things
>> work?
>>
>> I realize that defining bar as an inner function has the advantage of
>> being able to see variables in the namespace of foo.
>
> That is the main advantage, followed by reducing namespace pollution,
> but yes there is a very small performance penalty.
>
>
>>>> def outer(x):
> ... return x+1
> ...
>>>> def func(x):
> ... return outer(x+1)
> ...
>>>>
>>>> def func2(x):
> ... def inner(x):
> ... return x+1
> ... return inner(x+1)
> ...
>>>> assert func(37) == func2(37)
>>>> from timeit import Timer
>>>> t1 = Timer('func(23)', 'from __main__ import func')
>>>> t2 = Timer('func2(23)', 'from __main__ import func2')
>>>> t1.repeat()
> [1.5711719989776611, 0.82663798332214355, 0.82708191871643066]
>>>> t2.repeat()
> [1.8273210525512695, 1.1913230419158936, 1.1786220073699951]Very interesting, thanks for measuring this! -- Martin Geisler VIFF (Virtual Ideal Functionality Framework) brings easy and efficient SMPC (Secure Multi-Party Computation) to Python. See: http://viff.dk/.
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