/* 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 fo1;  // first/inner function object to call    FO2 fo2;  // second/outer function object to call  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(fo1(v));    }};