Re: [boost] Promise/A+ like javascript in cpp

Subject: Re: [boost] Promise/A+ like javascript in cpp
From: Gavin Lambert (gavinl_at_[hidden])
Date: 2018-07-27 00:50:03

On 26/07/2018 00:15, hawk x wrote:
> Javascript Promise creates a task chain to help develop asynchronized
> application with single thread.
> 
> I did not find a good implement of this kind of "Promise" in c++

std::future::then was proposed for C++17, but didn't make it in.  Boost 
does support it, however, as does an STL that implements the Concurrency 
TS (as std::experimental::future::then).

https://www.boost.org/doc/libs/1_67_0/doc/html/thread/synchronization.html#thread.synchronization.futures.then

Additionally, Boost.Asio supports using coroutines for implementing 
asynchronous tasks, which are even better than a then-chain and read 
even more like plain synchronous code.

https://www.boost.org/doc/libs/1_67_0/doc/html/boost_asio/overview/core/spawn.html

https://www.boost.org/doc/libs/1_67_0/doc/html/boost_asio/example/cpp11/spawn/echo_server.cpp

Currently coroutines are a pure library feature (supported by 
Boost.Context and Boost.Coroutine), but they are expected to be 
supported directly by C++20 compilers, and by C++17 compilers that 
implement the Coroutine TS (VS 2017 already supports co_await, for example).

https://www.boost.org/doc/libs/1_67_0/doc/html/boost_asio/overview/core/coroutines_ts.html

https://www.boost.org/doc/libs/1_67_0/doc/html/boost_asio/examples/cpp17_examples.html