howto load and unload a module

[Peter Hansen]

Guy Robinson wrote:
> Some of these scripts could potentially be quite large. Also the list of 
> scripts could be quite large. So the main reason for unloading modules 
> is to save memory.

Unless you're talking megabytes of bytecode (do a "wc *.pyc" on the 
compiled files and see) it's probably not worth the bother.

Still, assuming the modules are pure Python, and don't do strange things 
like inject references to themselves or their data into other places 
(i.e. other modules, including sys or builtins), it should be possible 
to unload them simply by deleting all references to them, *including* 
manually removing them from sys.modules.

How do you plan to import them?  Using the import statement, or 
__import__, or some other means?  How you do it will determine exactly 
what steps are required to free them up.

Note also that this won't necessarily release any memory back to the 
operating system, and it won't necessarily unload any extension modules 
or other shared libraries that are loaded.  The whole concept of 
"unloading" a module is pretty much undefined in Python, so whatever you 
can get is the best you can expect...

-Peter