Guido van Rossum wrote:

The issue here is that asyncio only interprets StopIteration as returning from the generator (with a possible value), while a Trollius coroutine must use "raise Return(<value>)" to specify a return value; this works as long as Return is a subclass of StopIteration, but PEP 479 will break this by replacing the StopIteration with RuntimeError.

I don't understand. If I'm interpreting PEP 479 correctly, in
'x = yield from foo', a StopIteration raised by foo.__next__()
doesn't get turned into a RuntimeError; rather it just stops the
sub-iteration as usual and its value attribute gets assigned to x.

As long as a Trollius coroutine behaves like something implementing
the iterator protocol, it should continue to work fine with
Return as a subclass of StopIteration.

Or is there something non-obvious about Trollius that I'm
missing?

--
Greg
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