Re: [boost] Boost.Outcome review - First questions

Subject: Re: [boost] Boost.Outcome review - First questions
From: Peter Dimov (lists_at_[hidden])
Date: 2017-05-24 15:36:48

Niall Douglas wrote:
> > 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.

Equality yes, initializer list no. This works:

#include <vector>
#include <system_error>

template<class T> class result
{
private:

    T t_;

public:

    result( T const& t ): t_( t )
    {
    }

    result( T&& t ): t_( std::move( t ) )
    {
    }

    result( std::error_code const & )
    {
    }
};

int main()
{
    result<std::vector<int>> r{ { 1, 2, 3 } };
}

> But essentially you've just specified Vicente's Expected there.

I don't think I have. Expected has more members.