Re: [boost] Common future base class (was Re: Boost.Fibermini-review September 4-13)

Subject: Re: [boost] Common future base class (was Re: Boost.Fibermini-review September 4-13)
From: Agustín K-ballo Bergé (kaballo86_at_[hidden])
Date: 2015-09-06 14:22:48

On 9/6/2015 1:35 PM, Peter Dimov wrote:
> Hartmut Kaiser wrote:
>
>>     template <typename Future...>
>>         requires(is_future<Future>)...
>>     future<tuple<Future...>> when_all(Future &&... f)
>>     {
>>         (await f)...;
>>         return make_tuple(std::forward<Future>(f)...);
>>     }
>
> I've always found when_any much more interesting than when_all. Is it as
> trivial to implement with await as when_all?
>

The await proposal already deals with heterogeneous futures (awaitable 
types). It comes with traits and customization points on top of which it 
is built. Using `await_suspend` one can attach a callback to an 
awaitable object that fires when the future becomes ready (without 
consuming it). An heterogeneous `when_all` would be built on top of 
`await_suspend`, plain `await` is optimal when one just want the 
semantic of `when_all`. Similarly, an heterogeneous `when_any` would use 
`await_suspend` to attach a callback to all awaitable objects, and the 
first callback to run would make the resulting future ready (potentially 
but not necessarily canceling all other callbacks).

Regards,
-- 
Agustín K-ballo Bergé.-
http://talesofcpp.fusionfenix.com