/* 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. */template <typename FO1, typename FO2>class Composer : private FO1, private FO2 {  public:    // constructor: initialize function objects    Composer(FO1 f1, FO2 f2)      : FO1(f1), FO2(f2) {    }    // ``function call'': nested call of function objects    double operator() (double v) {        return FO2::operator()(FO1::operator()(v));    }};