[Python-ideas] Python-ideas Digest, Vol 131, Issue 106

[Steven D'Aprano]

On Tue, Oct 31, 2017 at 06:02:34PM +1100, Chris Angelico wrote:

> > def single(i):
> >     try:
> >         v =i.next()
> >     except StopIteration:
> >         raise ValueError('No items')
> >     try:
> >         i.next()
> >     except StopIteration:
> >         return v
> >     else:
> >         raise ValueError('More than one item')
> >
> > print single(name for name in('bob','fred') if name=='bob')

Seems like an awfully complicated way to do by hand what Python already 
does for you with sequence unpacking. Why re-invent the wheel?


> Thanks :)
> 
> One small change: If you use next(i) instead of i.next(), your code
> should work on both Py2 and Py3. But other than that, I think it's
> exactly the same as most people would expect of this function.

Not me. As far as I can tell, that's semantically equivalent to:

def single(i):
    result, = i
    return result

apart from slightly different error messages.



-- 
Steve