On Tue, Dec 10, 2019 at 07:21:13PM -0600, Tim Peters wrote:
> [Tim]
> >> For me, most of the time, it's to have an obvious, uniform way to
> >> spell "non-destructively pick an object from a container (set, dict,
> >> list, deque, heap, tuple, custom tree class, ...)". I don't even have
> >> iterators in mind then, except as an implementation detail.
>
> [Steven]
> > You can't *non-destructively* pick the first (or next, or any) element
> > of an iterator.
>
> Obviously. That's why I wrote "container", and then gave 7 concrete
> examples in case that distinction was too subtle ;-)
It wasn't :-) but we're talking about adding a function to **itertools**
not "container tools", one which will behave subtly different with
containers and iterators. Your use-case ("first item in a container") is
not the same as the semantics "next element of an iterator", even if we
call the second one "first".
[...]
> I'm not at all bothered that for some arguments `first()` mutates
> state and for others it doesn't, no more than I'm bothered that `for x
> in iterable:` may or may not "consume" the iterable.
*shrug*
Okay, but I am. Iterating over an iterable is a very different use-case.
[...]
> While the meaning of `first()` is clear for any iterable argument.
Sorry Tim, I have to disagree. The meaning of `first` is:
return the first element of a sequence or container (in standard
iteration order), OR the *next* element of an iterator
and I don't think that this is even a little bit clear from the name.
--
Steven
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