/* The following code example is taken from the book * "C++ Templates - The Complete Guide" * by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002 * * (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002. * Permission to copy, use, modify, sell and distribute this software * is granted provided this copyright notice appears in all copies. * This software is provided "as is" without express or implied * warranty, and with no claim as to its suitability for any purpose. */#include "forwardparam.hpp"#include "functionptrt.hpp"template<typename RT, typename P1 = void,                       typename P2 = void,                      typename P3 = void>class FunctionPtr {  private:    typedef typename FunctionPtrT<RT,P1,P2,P3>::Type FuncPtr;    // the encapsulated pointer:    FuncPtr fptr;  public:    // to fit in our framework:    enum { NumParams = FunctionPtrT<RT,P1,P2,P3>::NumParams };    typedef RT ReturnT;    typedef P1 Param1T;    typedef P2 Param2T;    typedef P3 Param3T;    // constructor:    FunctionPtr(FuncPtr ptr)     : fptr(ptr) {    }    // ``function calls'':    RT operator()() {        return fptr();    }    RT operator()(typename ForwardParamT<P1>::Type a1) {        return fptr(a1);    }    RT operator()(typename ForwardParamT<P1>::Type a1,                  typename ForwardParamT<P2>::Type a2) {        return fptr(a1, a2);    }    RT operator()(typename ForwardParamT<P1>::Type a1,                  typename ForwardParamT<P2>::Type a2,                  typename ForwardParamT<P2>::Type a3) {        return fptr(a1, a2, a3);    }};