本来想好好写写C++ Traits的，刚刚接到interview的通知，先贴代码，改天再议。
/*
* cpp_traits.cpp
*
* Created on: 2010-4-26
* Author: volnet@tom.com
*/
#include <iostream>
// kinds of types for overloading.
struct undefined_type {};
struct int32_type {};
struct int64_type {};
// typedef some has_trivial_* for difference types.
template <class T>
struct type_traits {
typedef undefined_type has_trivial_type;
};
// define the partial specialization functions.
template <>
struct type_traits<int> {
typedef int32_type has_trivial_type;
};
template <>
struct type_traits<long> {
typedef int64_type has_trivial_type;
};
// the dispatcher method for all kinds of types.
template <class T>
void type_detect(T& p){
typedef typename type_traits<T>::has_trivial_type trivial_type;
type_detect(p, trivial_type());
}
// define the functions for dispatching.
template <class T>
void type_detect(T& p, undefined_type) {
std::cout << p;
std::cout << " // It's a undefined type, we have NOT found the dispatcher function." << std::endl;
}
template <class T>
void type_detect(T& p, int32_type) {
std::cout << p;
std::cout << " // It's a int32" << std::endl;
}
template <class T>
void type_detect(T& p, int64_type) {
std::cout << p;
std::cout << " // It's a int64" << std::endl;
}
int main(void) {
int int32num = 2010;
type_detect(int32num);
long int64num = 2010L;
type_detect(int64num);
std::string str = "2010";
type_detect(str);
std::cout << "-------end of program." << std::endl;
return EXIT_SUCCESS;
}