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 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
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