Hardening enviroment by overloading __import__?

[Steve Juranich]

If this is a FAQ, please let me know where the answer is.

I have in some code an 'eval', which I hate, but it's the shortest
path to where I need to get at this point.  I thought that one way I
could harden the enviroment against malicious code would be to
temporarily disable the import statement by overloading __import__,
but I tried what seemed obvious to me, and it didn't work.

What I want do do is something like this:

def __import__(*args, **kwargs):
    raise ImportError, 'Not so fast, bucko!'

eval(potentially_dangerous_string)

del __import__ # To get the builtin behavior back.

Am I barking up the wrong tree with __import__?? Where should I look
for this answer?

Thanks.
-- 
Steve Juranich
Tucson, AZ
USA