Duncan Mac-Vicar P.

A new discussion draft of the GNU GPL has been released. Go here to see more. Note the end of the Patents section in the changes guide:

specifically granted to recipients of the covered work under this License[, unless you entered into that arrangement, or that patent license was granted, prior to March 28, 2007].

I heard for first time about the Curiously Recurring Template Pattern when I read the Eigen library webpage. Now I found this example by Bruce Eckel that makes it much clearer:

//: generics/Mixins.cpp
#include
#include
#include
using namespace std;

templateT> class TimeStamped : public T {
  long timeStamp;
public:
  TimeStamped() { timeStamp = time(0); }
  long getStamp() { return timeStamp; }
};

templateT> class SerialNumbered : public T {
  long serialNumber;
  static long counter;
public:
  SerialNumbered() { serialNumber = counter++; }
  long getSerialNumber() { return serialNumber; }
};

// Define and initialize the static storage:
templateT> long SerialNumbered<T>::counter = 1;

int main() {
  TimeStamped<SerialNumbered<string> > mixin1, mixin2;
  mixin1.append(“test string 1″); // A string method
  mixin2.append(“test string 2″);
  cout << mixin1 << ” ” << mixin1.getStamp() << ” ” <<
    mixin1.getSerialNumber() << endl;
  cout << mixin2 << ” ” << mixin2.getStamp() << ” ” <<
    mixin2.getSerialNumber() << endl;
}

The effect you get is basically what you get with Ruby Mixins.