On Tue, 10 Dec 2019 at 00:26, Steven D'Aprano <st...@pearwood.info> wrote:
>
> On Tue, Dec 10, 2019 at 10:54:10AM +1300, Greg Ewing wrote:
>
> > Can you provide any insight into why you think it's better for
> > it never to raise an exception, as opposed to raising something
> > other than StopIteration when the iterator is empty and no
> > default is specified?
>
> Speaking for myself, not Guido, functions which raise are often
> difficult to use, especially if you can't "Look Before You Leap", since
> you have to wrap them in a try...except block to use them.
If the function allows a default to be supplied instead of raising
then you don't need try/except:
val = first(obj) # raises on empty
val = first(obj, default) # gives default on empty
That's how next works and also how first from more-itertools works.
--
Oscar
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