How to operate different class just one functionsone

Question

class A {};

class B {};

class C {};

class D {};

//A+B , A+C, B+C , A+D, D+C  namely all of these combinations will be possible just one functions 

Answer 1

template <typename T, typename U>
void foo(const T& pX, const U& pY)
{
    // do stuff
}

This isn't what you want, per se, as it makes a new function for each different combination of T and U, but it is one function template.

---

This prohibits T and U from being the same:

template <bool> struct static_assert {};
template <> struct<true> static_assert {};

#define STATIC_ASSERT(pValue) static_assert<(pValue)>()

// ...

template <typename T, typename U>
struct is_different
{
    static const bool value = true;
};

template <typename T>
struct is_different<T, T>
{
    static const bool value = false;
};

// ...

template <typename T, typename U>
void foo(const T& pX, const U& pY)
{
    STATIC_ASSERT(is_different<T, U>::value);

    // do stuff
}