//: C10:InnerClassIdiom.cpp

// Example of the "inner class" idiom.

#include <iostream>

#include <string>

using namespace std;

class Poingable {

public:

  virtual void poing() = ;

};

void callPoing(Poingable& p) {

  p.poing();

}

class Bingable {

public:

  virtual void bing() = ;

};

void callBing(Bingable& b) {

  b.bing();

}

class Outer {

  string name;

  // Define one inner class:

  class Inner1;

  friend class Outer::Inner1;

  class Inner1 : public Poingable {

    Outer* parent;

  public:

    Inner1(Outer* p) : parent(p) {}

    void poing() {

      cout << "poing called for "

        << parent->name << endl;

      // Acesses data in the outer class object

    }

  } inner1;

  // Define a second inner class:

  class Inner2;

  friend class Outer::Inner2;

  class Inner2 : public Bingable {

    Outer* parent;

  public:

    Inner2(Outer* p) : parent(p) {}

    void bing() {

      cout << "bing called for "

        << parent->name << endl;

    }

  } inner2;

public:

  Outer(const string& nm)

  : name(nm), inner1(this), inner2(this) {}

  // Return reference to interfaces

  // implemented by the inner classes:

  operator Poingable&() { return inner1; }

  operator Bingable&() { return inner2; }

};

int main() {

  Outer x("Ping Pong");

  // Like upcasting to multiple base types!:

  callPoing(x);

  callBing(x);

} ///:~