boost::bind实践2——来自《Beyond the C++ Standard Library ( An Introduction to Boost )》

直接代码：

代码段1：

 #include <iostream>
 #include <string>
 #include <boost/bind/bind.hpp>

 class some_class
 {
 public:
     typedef void result_type;
     void print_string(const std::string& s) const
     {    std::cout << s << '\n';  }
 };
 void print_string(const std::string s)
 {
     std::cout << s << '\n';
 }
 int main()
 {
     boost::bind(&print_string,_1)("Hello func!");  //ok
     some_class sc;
     boost::bind(&some_class::print_string,_1,_2)(sc,"Hello member!"); //ok
     boost::bind(&some_class::print_string,_1,_2)(some_class(),"Hello member!"); //ok
     boost::bind(&some_class::print_string,some_class(),"Hello member!")(); //ok
     boost::bind(&some_class::print_string,some_class(),"Hello member!"); //warning
     std::cout << std::endl;
 }

代码段2：

 #include <iostream>
 #include <string>
 #include <vector>
 #include <algorithm>
 #include <iterator>
 #include <list>

 #include <boost/bind/bind.hpp>

 class personal_info
 {
     friend std::ostream& operator<< (  std::ostream& os,const personal_info& pi);

     std::string name_;
     std::string surname_;
     unsigned int age_;
 public:
     personal_info(    const std::string& n,    const std::string& s,    unsigned int age):name_(n),surname_(s),age_(age) {}
     std::string name() const {    return name_;  }
     std::string surname() const {    return surname_;  }
     unsigned int age() const {    return age_;  }
 };
 std::ostream& operator<<(  std::ostream& os,const personal_info& pi)
 {
     os << pi.name() << ' ' <<    pi.surname() << ' ' << pi.age() << '\n';
     return os;
 }
 class personal_info_age_less_than :  public std::binary_function<  personal_info,personal_info,bool>
 {
 public:
     bool operator()(  const personal_info& p1,const personal_info& p2)
     {
         return p1.age()<p2.age();
     }
 };

 void main()
 {
     std::vector<personal_info> vec;
     vec.push_back(personal_info("Little","John",));
     vec.push_back(personal_info("Friar", "Tuck",));
     vec.push_back(personal_info("Robin", "Hood",));
     std::sort( vec.begin(),  vec.end(),
         boost::bind( std::less<unsigned int>(),
             boost::bind(&personal_info::age,_1),
             boost::bind(&personal_info::age,_2)));

     std::sort(vec.begin(),vec.end(),personal_info_age_less_than());

     std::vector<int> ints;
     ints.push_back();
     ints.push_back();
     ints.push_back();
     ints.push_back();
     //if (i>5 && i<=10) {  // Do something}
     int count=std::count_if( ints.begin(),
         ints.end(),
         boost::bind( std::logical_and<bool>(),
             boost::bind(std::greater<int>(),_1,),
             boost::bind(std::less_equal<int>(),_1,)));
     std::cout << count << '\n';
     std::vector<int>::iterator int_it=std::find_if( ints.begin(),
         ints.end(),
         boost::bind( std::logical_and<bool>(),
             boost::bind(std::greater<int>(),_1,),
             boost::bind(std::less_equal<int>(),_1,)));
     if (int_it!=ints.end())
     {
         std::cout << *int_it << '\n';
     }

     std::list<double> values;
     values.push_back(10.0);
     values.push_back(100.0);
     values.push_back(1000.0);
     //以下语句全部等价
     std::transform( values.begin(), values.end(), values.begin(), boost::bind( std::multiplies<double>(),0.90, boost::bind<double>( std::multiplies<double>(),_1,1.10)));
     std::transform( values.begin(), values.end(), values.begin(), boost::bind( std::multiplies<double>(),0.90, boost::bind( std::multiplies<double>(),_1,1.10)));
     std::transform( values.begin(), values.end(), values.begin(), boost::bind( std::multiplies<double>(),0.90, boost::bind( boost::type<double>(), std::multiplies<double>(),_1,1.10)));
     std::transform( values.begin(), values.end(), values.begin(), boost::bind<double>( std::multiplies<double>(), boost::bind<double>( std::multiplies<double>(),_1,1.10),0.90));

     std::copy( values.begin(),
         values.end(),
         std::ostream_iterator<double>(std::cout,"\n"));

 }

代码段3：

 #include <iostream>
 #include <string>

 #include <boost/bind/bind.hpp>

 class tracer
 {
 public:
     tracer() {    std::cout << "tracer::tracer()\n";  }
     tracer(const tracer& other) {    std::cout << "tracer::tracer(const tracer& other)\n";  }
     tracer& operator=(const tracer& other) {    std::cout <<      "tracer& tracer::operator=(const tracer& other)\n";    return *this;  }
     ~tracer() {    std::cout << "tracer::~tracer()\n";  }
     void print(const std::string& s) const {    std::cout << s << '\n';  }
 };

 void main()
 {
     tracer t;
     //boost::bind(&tracer::print, t, _1)(std::string("I'm called on a copy of t\n"));
     //boost::bind(&tracer::print, &t, _1)(std::string("I'm called on a copy of t\n"));
     //boost::bind(&tracer::print, boost::ref(t), _1)(std::string("I'm called on a copy of t\n"));
     //boost::bind(&tracer::print, boost::cref(t), _1)(std::string("I'm called on a copy of t\n"));
     boost::bind(&tracer::print, _1, _2)(&t, std::string("I'm called on a copy of t\n"));
 }

代码段4：

 #include <iostream>
 #include <string>
 #include <map>
 #include <algorithm>
 #include <iterator>

 #include <boost/bind/bind.hpp>

 void print_string(const std::string& s) {  std::cout << s << '\n';}
 void print_string2(const std::map<int,std::string>::value_type& s) {  std::cout << s.second << '\n';}
 void print_string3(const int& i) {  std::cout << i << '\n';}

 void main()
 {
     std::map<int,std::string> my_map;
     my_map[]="Boost";
     my_map[]="Bind";

     std::for_each( my_map.begin(),
         my_map.end(),
         boost::bind(&print_string,
         boost::bind( &std::map<int,std::string>::value_type::second,_1)));
     std::for_each( my_map.begin(),
         my_map.end(),
         boost::bind(&print_string2, _1));
     std::for_each( my_map.begin(),
         my_map.end(),
         boost::bind(&print_string3,
         boost::bind( &std::map<int,std::string>::value_type::first,_1)));
     //std::for_each( my_map.begin(),
     //    my_map.end(),
     //    boost::bind(&print_string, _1)(&std::map<int,std::string>::value_type::second)); //error

 }

代码段5：

 #include <iostream>
 #include <string>
 #include <map>
 #include <vector>
 #include <algorithm>

 #include <boost/bind/bind.hpp>

 class print_size
 {
     typedef std::map<std::string,std::vector<int> > map_type;
 public:
     typedef void result_type;
     result_type operator()(std::ostream& os, const map_type::value_type& x) const
     {
         os << x.second.size() << '\n';
     }
     result_type operator()(std::ostream& os, const map_type& x) const //no use
     {
         map_type::const_iterator iter = x.begin();
         os << iter->second.size() << '\n';
     }
 };

 int main()
 {
     typedef std::map<std::string,std::vector<int> > map_type;
     map_type m;
     m["Strange?"].push_back();
     m["Strange?"].push_back();
     m["Strange?"].push_back();
     m["Weird?"].push_back();
     m["Weird?"].push_back();
     std::for_each(m.begin(),m.end(), boost::bind(print_size(),boost::ref(std::cout),_1));
 }

代码段6：

 /*其它练习：boost::bind返回值*/

 #include <iostream>
 #include <string>
 #include <map>
 #include <vector>
 #include <algorithm>

 #include <boost/bind/bind.hpp>

 int TestAdd(int a, int b)
 {
     std::cout << "function inside" << std::endl;
     return a+b;
 }

 void main()
 {
     int ret = boost::bind(&TestAdd, _1, _2)(, );
     std::cout << "function outside ret = " << ret << std::endl;
 }

以上代码段全部通过VS2010 update1编译运行。