On Thursday, October 25, 2012 11:06:01 PM UTC-7, Paul Rubin wrote:
> Dan Loewenherz <dloewenh...@gmail.com> writes:
>
> > In this case, profile_id is "None" when the loop breaks. It would be
>
> > much more straightforward (and more Pythonic, IMO), to write:
>
> >
>
> > client = StrictRedis()
>
> > while client.spop("profile_ids") as profile_id:
>
> > print profile_id
>
>
>
> That is pretty loose, in my opinion. If the loop is supposed to return
>
> a string until breaking on None, the break test should explicitly check
>
> for None rather than rely on an implicit bool conversion that will also
>
> test as false on an empty string. Code that handles strings should do
>
> the right thing with the empty string. What you posted relies on an
>
> unstated assumption that the strings that come back are never empty.
>
I think this is a good point. However, I can't think of any situation where I'd
want to work with an empty string (in the applications I've worked with, at
least).
We also don't special case things like this just because x is an empty string.
If this "while EXPR as VAR" thing were to move forward, we shouldn't treat the
truth testing any differently than how we already do. IMO we should write our
applications with the understanding that '' will return False and work with
that.
Here's a workaround BTW. Just have that method return a tuple, and do the truth
testing yourself if you feel it's necessary.
while client.spop("profile_ids") as truthy, profile_id:
if not truthy:
break
print profile_id
Here, client.spop returns a tuple, which will always returns true. We then
extract the first element and run a truth test on it. The function we use is in
charge of determining the truthiness.
Dan
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