Function futures_test_sink::from_iter

pub fn from_iter<Item, FI, SSI, E>(
    poll_fallback: FI, 
    start_send_fallback: SSI
) -> impl Sink<Item, Error = E> where
    FI: Iterator<Item = Poll<Result<(), E>>> + Unpin,
    SSI: Iterator<Item = Result<(), E>> + Unpin,
    E: Unpin,
    Item: Unpin, 

This method allows to create Sink from iterators.

Any time you call poll_ready, poll_flush or push_close the next method will be called on poll_fallback iterator. If iterator return Poll::Pending the cx.waker().clone().wake() will be additionally called. Where cx is std::task::Context passed to poll_ready, poll_flush or poll_close function.

Any time you call start_send the inner implementation will discard item and return unwrapped item that start_send_fallback iterator return.

Panics

If poll_fallback or start_send_fallback iterator has no more elements. To prevent this use cycle method.