Any example to use __anext__ ?

[bachue]

I just noticed the signature of __anext__ is fn __anext__(<self>) -> Option<object> or IterANextOutput. I don't know how to use it when I have an instance of futures::stream::TryStream, is there any example about it ? Thanks.

[bachue]

I think there's a wrong design here, __anext__ are forced to return IterANextOutput, which is an enum and actually it's the same as IterNextOutput. Without Future, I have no idea whether the Iterator should yield or return, impl Future<Output=IterNextOutput> would be better.

[davidhewitt]

@bachue the lack of Future is deliberate for now; the question of integrating runtimes between Python and Rust is complex and for the moment PyO3 is waiting for better understanding of the solution space before trying to cover this (see #1632).

With apologies I don't think we have an example for __anext__ in the guide yet, however you can see one in our test suite here:

pyo3/tests/test_proto_methods.rs

Line 745 in 510c126

fn __anext__(&mut self) -> Option<Py<OnceFuture>> {