[−][src]Crate enum_future
This crate contains a simple macro for creating Future
-implementing enums containing futures.
It can be used as an alternative to futures::Either
if more than two variants are desired or
if one wants to give them more meaningful names. The enum is generic, in order to allow use
with complicated or unname-able types (combinators, closures, impl Future).
This macro doesn't allow for creating pub
enums, documenting them or deriving any other
trait. This should be fine in most cases, as it's intended to be used mainly in match
expressions returning different futures.
Derive macro would certainly provide more flexibility, but it'd also be more complicated and this simple macro solves my problem. If anyone is interested in contributing proc macro version, I'd be very happy to merge a PR!
This crate is no_std
and pre-2018-compatible, since it doesn't need anything fancy from
neither std
nor 2018 edition.
Example
#[macro_use] extern crate enum_future; use enum_future::futures::future::{Future, ok, err}; fn make_future(input: u64) -> impl Future<Item=bool, Error=&'static str> { enum_future!(Ret, Zero, One, Other); match input { 0 => Ret::Zero(ok(false)), 1 => Ret::One(ok(true)), _ => Ret::Other(err("Invalid input")), } } fn main() { assert_eq!(make_future(42).wait(), Err("Invalid input")); }
Re-exports
pub extern crate futures; |
Macros
enum_future | Creates a generic enum of type |