I have been looking for a C++ library for futures used via callbacks and
allowing composition like those in Scala or like the ones described at

https://engineering.fb.com/2015/06/19/developer-tools/futures-for-c-11-at-facebook/

I want to use these in a single thread with an event loop around some
select-like call so the std::future is not of much help.

Couldn't find anything readily available, any ideas?

TIA,
-Pavel

On Monday, 29 May 2023 at 06:21:54 UTC+3, Pavel wrote:
> I have been looking for a C++ library for futures used via callbacks and
> allowing composition like those in Scala or like the ones described at
>
> https://engineering.fb.com/2015/06/19/developer-tools/futures-for-c-11-at-facebook/
>
That looks like the mess of async react JavaScript. If someone does it
in C++ then that will likely be as awful.

> I want to use these in a single thread with an event loop around some
> select-like call so the std::future is not of much help.
>
> Couldn't find anything readily available, any ideas?
>
Maybe try boost.asio as it is closest to everything and more that one might
need for asynchronous processing in C++.

Öö Tiib wrote:
> On Monday, 29 May 2023 at 06:21:54 UTC+3, Pavel wrote:
>> I have been looking for a C++ library for futures used via callbacks and
>> allowing composition like those in Scala or like the ones described at
>>
>> https://engineering.fb.com/2015/06/19/developer-tools/futures-for-c-11-at-facebook/
>>
> That looks like the mess of async react JavaScript. If someone does it
> in C++ then that will likely be as awful.
I guess it's a matter of taste.

Reactive stuff has a solid theoretical background beneath it. From my
experience, Scala is the best host language to study it. From that, and
my work projects, I know exactly I would want from C++
implementation.(Although, even in Scala, the separation of concerns
between the asynchronous computation tooling and execution environment
is not strong enough to my taste).

The article I cited above should be good enough to show the fundamental
benefits I am looking for.

>
>> I want to use these in a single thread with an event loop around some
>> select-like call so the std::future is not of much help.
>>
>> Couldn't find anything readily available, any ideas?
>>
> Maybe try boost.asio as it is closest to everything and more that one might
> need for asynchronous processing in C++.
Thanks! Looked thru, they permit using std::future to complete I/O
operation, I did not notice this before. But, again, this is C++
std::future and I want composability and consuming results by handlers
rather than waiting (asio seems to offer the latter; I just never
figured out how to compose the future results conveniently).

Well, no luck so far. Maybe one day I get myself a few days and jot down
something of my own. Unlikely though.

-Pavel

On Mon, 29 May 2023 19:27:35 -0400
Pavel <pauldontspamtolk@removeyourself.dontspam.yahoo> wrote:
>Thanks! Looked thru, they permit using std::future to complete I/O
>operation, I did not notice this before. But, again, this is C++
>std::future and I want composability and consuming results by handlers
>rather than waiting (asio seems to offer the latter; I just never
>figured out how to compose the future results conveniently).

C++ async/future etc is handholding for programmers who find the concept of
creating and managing threads too complicated.