timeit's environment

[Alex Martelli]

<rurpy at yahoo.com> wrote:

> Why doesn't the following work?  It generates a "NameError: global
> name 'data' is not defined" error.
> 
>   import timeit
> 
>   global data
>   data = [3,8,4,8,6,0,5,7,2,1]
> 
>   env = "global data; x = data"
> 
>   print timeit.Timer('x.sort()', env).timeit()
>   print timeit.Timer('x.sort(cmp=cmp', env).timeit()
> 
> How can I get timeit() to see an external (to it) variable?
> (In the real program 'data' is very expensive to create and
> contains non-reproducable data and the two timeit calls
> must be run on identical objects.

You have to use 'from __main__ import data as x' rather than just say
'global data; x=data', because timeit is a separate module from your
__main__ one.


Alex