seanmonstar / futures-compat

A compatibility shim between futures v0.1 and v0.2.

futures-compat

This is a compatibility shim between [futures][] v0.1 and v0.2. It provides implementations that allow a type that implements Future from v0.1 to act as a Future from v0.2, and vice-versa.

Note: Task-local data doesn't really work, and getting it to work would require horrid unsafe hackery. It could probably be done if there was enough demand.

Example

Using a v0.1 Future as v0.2

extern crate futures_compat;
use futures_compat::futures_01::FutureInto02;

let futv01 = some_lib_that_hasnt_upgraded();

let futv02 = futv01.into_02_compat()
    .map(|val| {
        println!("map from v0.2! {:?}", val);
        Ok(())
    });

// spawn in a futures 0.2 executor

Using a v0.2 Future as v0.1

extern crate futures_compat;
use futures_compat::futures_01::FutureInto01;

let futv02 = some_lib_using_the_new_hotness();
let exec = get_my_current_executor();

let futv01 = futv02.into_01_compat(exec)
    .map(|val| {
        println!("map from v0.1! {:?}", val);
        Ok(())
    });

// spawn in a futures 0.1 executor
futv01.wait().unwrap();

futures-compat's Issues

Make futures crate public

You run into a problem if you want to use futures v0.1 and futures v0.2 in the same program: Cargo will only allow you to use one of them because of the name clash (I am talking about futures v0.2, not futures-core v0.2).

You could circumvent this problem if futures-compat would change a single line in lib.rs:

- extern crate futures;
+ pub extern crate futures;

In that case the programmer could use these dependencies for his programm:

[dependencies]
futures-compat = "*"
futures = "0.2.1"

and still use both Future types in the program (including async and await macros):

extern crate futures_compat;
extern crate futures;

use futures_compat::futures::Future as Future1;
use futures::Future as Future2;

Example

An example would really help to get started.

I tried to write an example to convert futures2 to futures1 including async and await macros: https://gist.github.com/manuels/d6a7d33f3a566a62c33cbd77bdf309a8

PS: it could be a little overcomplicated with the __rt module, but I didn't have a better idea to make it work