Should we raise something like "'int' object is not an asynchronous iterable", instead of "'async for' requires an object with __aiter__ method, got int"?


>>> foo().send(None)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in foo
TypeError: 'async for' requires an object with __aiter__ method, got int


>>> for i in 1: pass
...
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'int' object is not iterable

Did you get multiple complaints about this? The existing error doesn't seem so bad.

IMHO the current message is clear enough.

I saw this reddit thread: https://www.reddit.com/r/Python/comments/3ewnwq/async_function_as_generator_for_async_for/ where people are struggling with understanding how 'async for' works.  Which led me to check what error messages we raise when we pass a wrong object to it.  Turns out the message is fine, but different from what we raise on iter(1) etc.

In tandem with an "asynchronous iterable" glossary entry, that could be a nice improvement.

Even without such a change the first hit for "python asynchronous iterable" is PEP 492, so it will get folks pointed in the right direction.

Do what you think is best.