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Loading Modules

Peter Otten __peter__ at web.de
Wed Apr 13 12:02:48 EDT 2011 
Cornelius Kölbel wrote:

> I am wondering about loading modules.What is a good way of doing this?
> 
> In my code I got one single function, where I need some functionality
> from a built-in module.

built-in modules are always imported by definition, so you cannot save space 
or time by moving the import statement into the function. You can find the 
true built-in modules with

sys.builtin_module_names

and the modules that may have been imported indirectly by other modules you 
are using with

sys.modules

> Is it a better way to load the module only within the function
>   pro: the function will only be hit every now and then or only with a
> probability of 90%.
>          So in 90% cases the modules will not be loaded. (preserve
> resources)
> 
> What is the balance between speed, resources and code style?

I doubt that you'll save a significant amount of space/time, and you make 
your module's dependencies less obvious.

> Is there a pythonian way for deciding in which case to do what?

The pythonic approach is to measure; run your script with and without the 
tentative optimization and then decide whether the extra complication pays 
off.
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