I guess I knew the whole “you can’t use next on iterables” in the sense that I’ve never tried it.
I TIL’d about the default value for next.
All ‘next’ does is call ‘next’, which is part of the spec for ‘iterator’s.
Iterables return iterators when ‘iter’ is called on them. So they don’t need to support ‘next’ natively, their corresponding iterator does that.
Exactly what I wanted to say. I understand teaching by example, but this is more like teaching by trial and error…
Yea, it is losing the forest for the trees. Next should be taught as part of iterators and for loops. It makes sense there. It doesn’t really stand on its own much.
To be honest, I’m not sure why it is a built in function… I feel like saying that python calls the ‘next’ function of your class when iterating is enough. But maybe I’m missing something.
The
defaulthandling is pretty important.What I find more interesting are 1. the two-argument form of
iter, and 2. the__getitem__auto-implementation that causes there to be two incompatible definitions ofIterable.(btw your comments are using accidental formatting; use backticks:
__next__)
