Re: [boost] Outcome v2 is feature complete

11 Jul 2017

      Andrzej Krzemienski wrote:
...
maybe result indeed looks suspicious, but using 
result might come as quite natural:
auto select_first_error(vector v)
  -> result
{
  if (!v.empty())
    return result{in_place_index<0>, v[0]};
  else
    return result{in_place_index<1>, MyErrc::NoFirstElement};
}
Yes, and the next logical step is to look at those magic constants 0 and 1 
and say, hey, why not name these, would help readability.

if( !v.empty() )
{
    return { in_place_value, v[0] };
}
else
{
    return { in_place_error, MyErrc::NoFirstElement };
}

Re the multi-arg constructor, one obvious use case is this:

    return { errno, std::generic_category() };

or

    return { GetLastError(), std::system_category() };

although the main purpose is to forward arguments to custom ECs.

I'm working on a prototype that showcases these but it's not ready yet.

Re: [boost] Outcome v2 is feature complete

Peter Dimov