Using multiple templates with the same class in C++ - c++

Question

I have the following code in C++ -
template <class T>
class TempClass {
T value;
public:
TempClass(T item)
{
value = item;
}
T getValue()
{
return value;
}
};
int main()
{
TempClass<string>* String =
new TempClass<string>("Rin>Sakura");
cout << "Output Values: " << String->getValue()
<< "\n";
class TempClass<int>* integer = new TempClass<int>(9);
cout << "Output Values: " << integer->getValue();
}
What I would like to do is use multiple templates with the above class TempClass. I know one way of doing this is by using
template <class T1, class T2>
, but if I do that then all instances of the class must have 2 template arguments. What I want to do is something more like :
if (flag)
//initialize an instance of TempClass with one template
TempClass<string> s("haha");
else
//initialize an instance of TempClass with 2 templates.
TempClass<string, int> s("haha", 5);
Is there a way to do this without using another new class?

Answer 1

You can use a variadic template and an std::tuple to hold values of distinct types. Minimal example:
template<class... Ts>
class TempClass {
using Tuple = std::tuple<Ts...>;
Tuple values;
public:
TempClass(Ts... items) : values{items...} {}
template<std::size_t index>
std::tuple_element_t<index, Tuple> getValue() const {
return std::get<index>(values);
}
};
int main() {
TempClass<int, std::string, double> tc1{0, "string", 20.19};
std::cout << tc1.getValue<2>(); // Output: 20.19
}
std::tuple_element_t is available only since C++14. In C+11 you should be more verbose: typename std::tuple_element<index, Tuple>::type.