|  | Home | Libraries | People | FAQ | More | 
            Return a string
            pointer if this is a string, else return nullptr
          
string const* if_string() const;
            If this->kind() == kind::string,
            returns a pointer to the underlying object. Otherwise, returns nullptr.
          
The return value is used in both a boolean context and to assign a variable:
if( auto p = jv.if_string() ) return *p;
Constant.
No-throw guarantee.