Class BoundValueRefBase

tests/catch.hpp:7007–7009

        virtual auto isFlag() const -> bool { return false; }
    };
    struct BoundValueRefBase : BoundRef {
        virtual auto setValue( std::string const &arg ) -> ParserResult = 0;
    };
    struct BoundFlagRefBase : BoundRef {
        virtual auto setFlag( bool flag ) -> ParserResult = 0;
        virtual auto isFlag() const -> bool { return true; }