class data
{
public:
data(int d) : d_(d)
{
}
public:
data& operator + (data& d)
{
cout << "operator + (data& d)" << endl;
this->d_ += d.d_;
return *this;
}
const data& operator + (const data& d) const
{
cout << "operator + (const data& d)" << endl;
return *this;
}
data&& operator + (data&& d)
{
cout << "operator + (data&& d)" << endl;
return std::move(*this);
}
const data&& operator + (const data&& d) const
{
cout << "operator + (const data&& d)" << endl;
return std::move(*this);
}
private:
int d_;
};
template <typename T1, typename T2>
T1 add(T1&& t1, T2&& t2)
{
return std::forward<T1>(t1) + std::forward<T2>(t2);
{
public:
data(int d) : d_(d)
{
}
public:
data& operator + (data& d)
{
cout << "operator + (data& d)" << endl;
this->d_ += d.d_;
return *this;
}
const data& operator + (const data& d) const
{
cout << "operator + (const data& d)" << endl;
return *this;
}
data&& operator + (data&& d)
{
cout << "operator + (data&& d)" << endl;
return std::move(*this);
}
const data&& operator + (const data&& d) const
{
cout << "operator + (const data&& d)" << endl;
return std::move(*this);
}
private:
int d_;
};
template <typename T1, typename T2>
T1 add(T1&& t1, T2&& t2)
{
return std::forward<T1>(t1) + std::forward<T2>(t2);
}
int main()
{
// pass lvalue to lvalue reference on data object
data lvalue(1);
add(lvalue, lvalue);
// pass const lvalue to const lvalue reference on const data object
const data const_lvalue(2);
add(const_lvalue, const_lvalue);
// pass rvalue to const rvalue reference on const data object
add(data(3), data(3));
// pass const rvalue to const rvalue reference on const data object
add(p(), p());
}