Exec Statement Question

[Carsten Haese]

Victor Subervi wrote:
> Taking out the parenthesis did it! Thanks. Now, you state this is an
> option of last resort. Although this does indeed achieve my desired aim,
> here is a complete example of what I am trying to achieve. The following
> is from 'createTables2.py':
> 
>   for table in tables:
>     try:
>       exec 'from options import %s' % table
>     except:
>       pass
>     try:
>       exec '%s()' % table
>     except:
>       pass

Here's a rough sketch of rewriting that snippet in a way that uses
attribute lookup instead of dynamic code execution:

#---------------------------------------#
import options
for table in tables:
    tablefunc = getattr(options, table)
    tablefunc()
#---------------------------------------#

The main ideas behind this approach are:

1) Rather than importing the functions from the options module piecemeal
into the local namespace, I just import the entire options module as its
own separate namespace.

2) I use getattr on that separate namespace to look up the desired
function object from the options module. I assign the local name
<<tablefunc>> to the resulting function object.

3) I call that function using the local name <<tablefunc>>.

HTH,

--
Carsten Haese
http://informixdb.sourceforge.net