// spec.cpp - demonstrate class templates

// class pair is now specialized for ints (in a silly way)
// member function left is now specialized for doubles

#include <iostream.h>

//----< generic pair class >-----------------------------------

template <class L, class R> class pair {
  public:
    pair(const L& larg, const R&  rarg) : lft(larg), rgt(rarg) { }
       L  left() const; // { return lft; }
       R right() const { return rgt; }
    void  left(const L& larg) { lft = larg; }
    void right(const R& rarg) { rgt = rarg; }
  private:
    L lft;
    R rgt;
};

//----< specialized pair class for ints >----------------------

class pair<int,int> {
  public:
    pair<int,int> (const int& larg, const int&  rarg)
                                    : lft(larg), rgt(rarg) {
      cout << "  specialized constr for int\n"; }
       int  left() const { return lft; }
       int right() const { return rgt; }
    void  left(const int& larg) { lft = larg; }
    void right(const int& rarg) { rgt = rarg; }
  private:
    int lft;
    int rgt;
};

//----< generic left member function >-------------------------

template<class L, class R>
L pair<L,R>::left() const { return lft; }


//----< specialized left member function for doubles >---------

double pair<double,double>::left() const {
            cout << "  specialized left for doubles\n"; return lft;
}

//----< generic function returning pairs >---------------------

pair<int,double> funct(int x, double y) {

  pair<int,double> temp(2*x,x+y);
  return temp;
}
/**/
//----< test stub for specialized template based class >-------

void main() {

  cout << "Demonstrating Template Classes - pair<L,R>\n"
       << "==========================================\n\n";
  int x = 3; double y = 5.555;

//  pair<int,double> myPair;    compiler won't generate default
//                              ctor because another ctor was
//                              defined.  See Stroustrup, pg 570
//  myPair = funct(x,y);        So this doesn't work

  cout << "  funct returned myPair("
       << funct(x,y).left()
       << ", "
       << funct(x,y).right()
       << ")" << endl<< endl;
  pair<int,int>       myInts(2,3);      myInts.left();
  pair<double,double> myDbls(2.5,3.5);  myDbls.left();
}