OnJava8-Examples/generics/Mixins.cpp

// 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
*/