2016-08-15: C++ traits

#include <stdio.h>

template <typename T>
struct TraitsHelper {
     static const bool isPointer = false;
};

template <typename T>
struct TraitsHelper<T*> {
     static const bool isPointer = true;
};

template<typename T>
class Test
{
public:
    void Func()
    {
        if(TraitsHelper<T>::isPointer)
        {
            printf("TypeParm is pointer\n");
        }
        else
        {
            printf("TypeParm not pointer\n");
        }
    }
};

template <typename T>
struct computer_traits {
     typedef T param_type;
};

template <>
struct computer_traits<int> {
     typedef int param_type;
};
template <>
struct computer_traits<float> {
     typedef float param_type;
};

template<typename T>
class Computer
{
public:
    typedef T num_type;
    typedef typename computer_traits<num_type>::param_type traits_type;
    traits_type Add(traits_type a, traits_type b)
    {
        return a+b;
    }
};

int main()
{
    Test<int> intTest;
    intTest.Func();

    Test<int*> pointerTest;
    pointerTest.Func();

    Computer<float> computerFloat;
    printf("float add = %f\n", computerFloat.Add(3.2, 5.0));

    Computer<int> computerInt;
    printf("float add = %d\n", computerInt.Add(3.2, 5.0));

    return 0;
}

参考资料

http://www.cnblogs.com/youthlion/archive/2011/12/01/2255618.html

http://blog.csdn.net/my_business/article/details/7891687

http://www.cnblogs.com/pugang/archive/2012/10/17/2727378.html