/* 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 <iostream>class SortTracer {  private:    int value;                // integer value to be sorted    int generation;           // generation of this tracer    static long n_created;    // number of constructor calls    static long n_destroyed;  // number of destructor calls    static long n_assigned;   // number of assignments    static long n_compared;   // number of comparisons    static long n_max_live;   // maximum of existing objects    // recompute maximum of existing objects    static void update_max_live() {        if (n_created-n_destroyed > n_max_live) {            n_max_live = n_created-n_destroyed;        }    }  public:    static long creations() {         return n_created;     }    static long destructions() {         return n_destroyed;     }    static long assignments() {         return n_assigned;     }    static long comparisons() {         return n_compared;     }    static long max_live() {         return n_max_live;     }  public:    // constructor    SortTracer (int v = 0) : value(v), generation(1) {        ++n_created;        update_max_live();        std::cerr << "SortTracer #" << n_created                  << ", created generation " << generation                  << " (total: " << n_created - n_destroyed                  << ")\n";    }       // copy constructor    SortTracer (SortTracer const& b)      : value(b.value), generation(b.generation+1) {        ++n_created;        update_max_live();        std::cerr << "SortTracer #" << n_created                  << ", copied as generation " << generation                  << " (total: " << n_created - n_destroyed                  << ")\n";    }    // destructor    ~SortTracer() {        ++n_destroyed;        update_max_live();        std::cerr << "SortTracer generation " << generation                  << " destroyed (total: "                   << n_created - n_destroyed << ")\n";    }    // assignment    SortTracer& operator= (SortTracer const& b) {        ++n_assigned;        std::cerr << "SortTracer assignment #" << n_assigned                   << " (generation " << generation                  << " = " << b.generation                   << ")\n";        value = b.value;        return *this;    }    // comparison    friend bool operator < (SortTracer const& a,                             SortTracer const& b) {        ++n_compared;        std::cerr << "SortTracer comparison #" << n_compared                   << " (generation " << a.generation                  << " < " << b.generation                   << ")\n";        return a.value < b.value;    }    int val() const {         return value;    }};