dynamic module import?

[James Stroud]

Lawson Hanson wrote:

> So is there any way to get Python to import the named module
>     without just doing "from dummy import *", because I will
>     not know that the user wants to use the "dummy" module
>     until run-time ... I'm trying to import control data
>     for different run scenarios which will be defined in
>     differently named Python modules which the user will
>     specify at run-time with a command-line option
> 
> And help with this would be most appreciated

For the sake of humanity, I must try to talk you out of this. Well, it's 
not that serious, but dynamic import confuses programs that inspect code 
like py2exe, etc. I think it is likely that you will find the day that 
you regret trying so hard to 'import *' dynamically. A more maintainable 
way is to simply map the command line argument to an import statement 
and keep your namespaces clean:

"""importer_module"""
import sys
import dummy
import bonafide
modules = {"dummy" : dummy, "bonafide" : bonafide}
module = modules[sys.argv[1]]


If you have several modules that themselves might need the conditional 
imports, simply put the import statements in a separate module (e.g. 
"importer_module" and do something like


"""another_module"""
from importer_module import module


If you simply don't want to import a bunch of modules, use an if/then 
statement. In any event, I advise you to not design your code or usage 
around dynamic imports using the __import__() statement or exec().

James



-- 
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095

http://www.jamesstroud.com