Re: [boost] Futures

Subject: Re: [boost] Futures
From: Niall Douglas (s_sourceforge_at_[hidden])
Date: 2015-01-20 19:24:14

On 16 Jan 2015 at 18:07, Gavin Lambert wrote:

> > 1. They tie your code into "future islands" which are fundamentally
> > incommensurate with all code which doesn't use the same future as
> > your code. Try mixing code using boost::future and std::future for
> > example, it's a nightmare of too easy to be racy and unmaintainable
> > mess code. If Compute provided a boost::compute::future, it would yet
> > another new future island, and I'm not sure that's wise design.
> 
> Is there somewhere I can read up some more on this issue?

I can't think of anywhere except this thread really. I guess anyone 
who has tried mashing together different types of futures knows what 
a future island is immediately.

> Perhaps I have not put enough thought into it, but it seems like it 
> should be trivial to create a wrapper to convert a std::future into a 
> boost::future or the reverse.  (It's slightly less trivial if you want 
> to use a mixture of futures and shared_futures, but it should still be 
> manageable.)

Indeed a wrapper is trivial. The problem is where library A uses 
boost::future and library B uses std::future and your code has to 
work with both. In case you think that probably okay for open source 
libraries, imagine mixing up a precompiled binaries compiled against 
different MSVCRT.DLL where "std::future" isn't the same thing.

A codebase I currently work with uses both types of future in the 
same codebase. We use std::async to work around it a lot 
unfortunately.

Niall

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