// generics/Mixins.cpp // (c)2020 MindView LLC: see Copyright.txt // We make no guarantees that this code is fit for any purpose. // Visit http://OnJava8.com for more book information. #include <string> #include <ctime> #include <iostream> using namespace std; template<class T> class TimeStamped : public T { long timeStamp; public: TimeStamped() { timeStamp = time(0); } long getStamp() { return timeStamp; } }; template<class T> class SerialNumbered : public T { long serialNumber; static long counter; public: SerialNumbered() { serialNumber = counter++; } long getSerialNumber() { return serialNumber; } }; // Define and initialize the static storage: template<class T> long SerialNumbered<T>::counter = 1; class Basic { string value; public: void set(string val) { value = val; } string get() { return value; } }; int main() { TimeStamped<SerialNumbered<Basic>> mixin1, mixin2; mixin1.set("test string 1"); mixin2.set("test string 2"); cout << mixin1.get() << " " << mixin1.getStamp() << " " << mixin1.getSerialNumber() << endl; cout << mixin2.get() << " " << mixin2.getStamp() << " " << mixin2.getSerialNumber() << endl; } /* Output: test string 1 1452987605 1 test string 2 1452987605 2 */