pythonic way to optimize access to imported value?

[Neal Norwitz]

On Tue, 12 Nov 2002 20:32:02 -0500, Greg Ewing wrote:

> Bengt Richter wrote:
> 
>>  >>> def mkfoo():
>>  ...     from math import pi
>>  ...     def foo():
>>  ...         return pi
>>  ...     return foo
>>  ...
>> 
>> What would be best Pythonic practice for getting a foo2? It seems like
>> if there were a way to say "do this part once at compile time"
> 
> 
> It's not really compile-time that we want to do it, but module load
> time, or perhaps function definition time.
> 
> One way would be to use a default-argument hack:
> 
>     import math
> 
>     def foo(m = math):
>        return m.pi
> 
> but this has all the usual drawbacks of the default-argument hack.
> 
> This suggests that perhaps there should be a way of getting something
> that is just like a default argument, except that it's not part of the
> argument list. Maybe
> 
>     def foo():
>        const m = math
>        return m.pi
> 
> The "const" statement would be evaluated when the "def" was executed,
> and "m" would appear in the local namespace when the function was
> called.
> 
> Although "const" might not be the best name for it, since it's not
> really a constant, more like a local with an initial value.
 
You can *kinda* do this with 2.1 (at least) and up:

	>>> import math
	>>> def foo(): return foo.pi
	... 
	>>> foo.pi = math.pi
	>>> foo()
	3.1415926535897931

I realize this isn't exactly what you are asking for,
but it is a way that works today.

Neal