How to avoid this kind of repetition

I have code similar to this:

#include <string>

class A{
public:
    std::string &get(){
        return s;
    }

    const std::string &get() const{
        return s;
    }

    std::string &get_def(std::string &def){
        return ! s.empty() ? s : def;
    }

    // I know this might return temporary
    const std::string &get_def(const std::string &def) const{
        return ! s.empty() ? s : def;
    }

private:
    std::string s = "Hello";
};

I am wondering is there easy way to avoid code repetition in get() functions?