[Tutor] Fw: Misc question about scoping

[Steven D'Aprano]

On Fri, 4 Jun 2010 09:00:13 am ALAN GAULD quoted Tino Dai who wrote:

> "Tino Dai" <oberoc at gmail.com> wrote
[...]
> >>     I have code that is unpythonic in many places. It works, but
> >> it's ugly. One of those unpythonic places is I'm initializing some
> >> variable such as a list,dict, or whatever outside of if/while/for
> >> in block to use later. So, I'm cleaning those places up.
> >>
> >>      For example, my present code looks like:
> >>      L = []     # Needed or L doesn't exist outside of for loop
> >> below for o in a:
> >>         if o.someAttribute > someConstant:
> >>            L.append(o.someOtherAttribute)
> >>
> >>      .... later in code ....
> >>      <some use of L>


There's nothing unpythonic about that code. For loops existed in Python 
since the very earliest days, which is *at least* 1991, while list 
comprehensions are a newcomer.

But if you insist on a list comprehension, you can re-write the above 
for-loop as:

L = [o.someOtherAttribute for o in a if o.someAttribute > someConstant]



-- 
Steven D'Aprano