exec and locals

[Steven D'Aprano]

On Wed, 26 Feb 2014 23:20:10 -0500, Dave Angel wrote:

> Before I would use exec,  I'd look hard at either generating a
>  source file to import,  

Yes, I went through the process of pulling out the code into a separate 
module, but that just made more complexity and was pretty nasty. If the 
function was stand-alone, it might have worked, but it needed access to 
other code in the module, so there were circular dependencies.


> or using a preprocessor. 

I don't think that it's easier/better to write a custom Python 
preprocessor and run the entire module through it, just to avoid a three-
line call to exec.

Guys, I know that exec is kinda dangerous and newbies should be 
discouraged from throwing every string they see at it, but this isn't my 
second day Python programming, and it's not an accident that Python 
supports the dynamic compilation and execution of source code at runtime. 
It's a deliberate language feature. We're allowed to use it :-)


> And if this code was
>  to be installed,  make the version choice or the preprocess step happen
>  at install time.

Completely inappropriate in my case. This is a module which can be called 
from multiple versions of Python from a single installation.


-- 
Steven