模板结构中的重载运算符

Question

I have the following scenario: I have a struct template<typename CType, int D> struct Point in which I want to overload the operators < and >. Here comes the catch and the point I am not sure about: I want different implementations of < and > depending on if CType is float/double or int. Right now I'm doing this using typid from typeinfo, but I feel like this is not elegant. How do I go about doing this in a clean way?

Answer 1

Here is one option (using non-member operators):

template<typename CType, int D>
bool operator<( Point<CType, D> const &p1, Point<CType, D> const &p2)
{
    // generic logic
} 

template<int D> bool operator<( Point<float, D> const &p1, Point<float, D> const &p2 )
{
    // logic for float
} 

It might be possible to replace float with an enable_if to make a version that works for all types of a certain type trait (eg have a single specialization for all floating point types).

Answer 2

Live demo link.

#include <iostream>
#include <type_traits>

template <typename CType, int D>
struct Point
{
    template <typename T = CType>
    auto operator<(int t) -> typename std::enable_if<std::is_same<T, int>::value, bool>::type
    {
        std::cout << "int" << std::endl;
        return true;
    }

    template <typename T = CType>
    auto operator<(float t) -> typename std::enable_if<std::is_same<T, float>::value, bool>::type
    {
        std::cout << "float" << std::endl;
        return true;
    }
};

int main()
{
    Point<int, 1> pi;
    Point<float, 1> pf;
    pi < 5;
    pf < 3.14f;
    pi < 3.14f; // forced to apply operator<(int) 
}