pub fn poll_fn<T, E, F>(f: F) -> PollFn<F>
Expand description
Creates a new stream wrapping around a function returning Poll
.
Polling the returned stream delegates to the wrapped function.
ยงExamples
use futures::prelude::*;
use futures::stream::poll_fn;
let mut counter = 1usize;
let read_stream = poll_fn(move |_| -> Poll<Option<String>, std::io::Error> {
if counter == 0 { return Ok(Async::Ready(None)); }
counter -= 1;
Ok(Async::Ready(Some("Hello, World!".to_owned())))
});