interactive execution

[Jeff Shannon]

Jive Dadson wrote:
> Yeah.  I got it.
> 
> exec "foo = 555" in globals(), locals() does the trick.

You can do it with your own dicts, too -- but they must already exist, 
exec doesn't create them out of nowhere.

 >>> myglobals = {'a':2, 'b':5}
 >>> mylocals = {'c': 3}
 >>> exec "d = a * b + c" in myglobals, mylocals
 >>> myglobals
{'a': 2, '__builtins__': {...}, 'b': 5}
 >>> mylocals
{'c': 3, 'd': 13}
 >>>

This gives you some control over what the exec'ed statement actually 
sees, as well as what happens with the results.  (But as I mentioned 
before, there is no real security here if you're exec'ing arbitrary 
code -- there's no sandboxing involved, and the exec'ed string *can* 
use that __builtins__ reference (among other things) to do all sorts 
of malicious stuff.)

Jeff Shannon
Technician/Programmer
Credit International