If someone comes along with an obviously superior design to both Expected and Outcome, that would be an enormous win.
There's nothing much to improve upon in result/outcome as long as 4/5 of the stuff is thrown out.
template<class T> class result { public:
result(); // T() or error, legitimate fork
result( T const& ); result( T&& );
result( std::error_code const& ) noexcept;
result( result const& ); result( result&& );
result( outcome const& ); //? result( outcome && ); //?
bool has_value() const noexcept; bool has_error() const noexcept;
T value() const; T value() &&;
std::error_code error() const;
explicit operator bool() const noexcept;
void swap( result& ) noexcept; };
That's literally it.
You're missing a few bits of necessary stuff, like equality operators, initialiser list construction and so on. But essentially you've just specified Vicente's Expected there. If you watched my ACCU talk video, when I explain Expected I show the additional member functions over Optional on a second slide and it's only four or five additions. Peter do you think you might be happy if I extended Outcome's Expected implementation to instead be: template<class T, class EC = std::error_code, class E = void> class expected; Now expected<T, EC, E> would exactly mirror outcome/result/option, except with no empty state and with narrow contracts on the observers. Then it would be a perfect alternative to outcome/result/option. Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/