Function expectedValueOrThrow

source/MRPython/MRPython.h:237–250

// Like `e.value()`, but throws using `throwExceptionFromExpected` (which is better, because it allows Python to see the proper error message), and also supports `T == void`.
template <typename T>
[[nodiscard]] decltype(auto) expectedValueOrThrow( T&& e )
{
    if ( e )
    {
        if constexpr ( std::is_void_v<typename std::remove_cvref_t<T>::value_type> )
            return;
        else
            return *std::forward<T>( e );
    }
    else
    {
        throwExceptionFromExpected( e.error() );
    }
}

template<typename R, typename E, typename... Args>
auto decorateExpected( std::function<Expected<R, E>( Args... )>&& f ) -> std::function<R( Args... )>