On 15 Mar 2015 at 16:59, Mikael Persson wrote:
Should we use exceptions or return codes ?
I agree with all that you've said on this. It's very true that one of the nice benefits of exceptions is that they allow you to retain the nice functional / expression syntax, that is, instead of having to do each operation on its own line, grabbing the error-code and checking it.
The lightweight non-allocating future<T, E> I proposed here many months ago is functional, returns any unexpected type E you like, and the compiler should completely elide the future code if it isn't necessary. In other words, you write your code with promise-futures, and only if they cross a thread boundary does the compiler actually generate any code for them. I decided against implementing those properly, but AFIO v1.4's afio::future<T> will be non-allocating and lightweight (i.e. elidable by the optimiser). It also will carry either a type T, an error_code or an exception_ptr, so it's a fixed function constexpr variant transport. I'll be donating that afio::future<T> to Boost.Thread v5 probably as lightweight_future<T>. Someone else may decide to turn it into a totally generic solution suitable for replacing future/promise in C++ 17. Or they may not. Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/