Getting E back from reactor::poll_evented::PollEvented<E>

[baloo]

my use case is:

• create a socket with a lib
• set socket in non-blocking
• connect the socket
• register socket with tokio (with PollEvented).
• once socket is connected, deregister the socket from tokio.
• mess with the socket (with the lib)
• once mess is done,
• register the socket again with tokio

the PollEvented<E>.deregister signature is deregister(self, handle: &Handle) -> Result<()>, so once my socket is registered with PollEvented I can't have it back.

I'd like deregister to look like this instead:
deregister(self, handle: &Handle) -> Result<E>

[alexcrichton]

Thanks for the report! I think this definitely makes sense to solve in the tokio-rs/tokio-rfcs#3 design!