boost::function | 易学教程

// 忽略警告
#define _SCL_SECURE_NO_WARNINGS
#pragma warning(disable : 4996)
#include <assert.h>
#include <iostream>
#include <boost/bind.hpp>
#include <boost/function.hpp>
#include <boost/ref.hpp>
#include <boost/assign/list_of.hpp>// list_of
using namespace boost;
using namespace std;
#include <algorithm>// for_each

int Plus(int a, int b)
{
return a + b;
}

struct demo
{
   int add(int a, int b)
   {
       return a + b;
   }
   int operator()(int a) const
   {
       return a * a;
   }
};

template<typename T>
struct summary
{
   typedef void result_type;
   T sum;
   summary(T v = T()) :sum(v){}
   void operator()(T const &x)
   {
       sum += x;
       print(sum);
   }
   void print(T num){ cout << num * num << endl; }
};

// 用于回调
void call_back_print(int n)
{
   cout << n << endl;
}
class call_back
{
private:
   typedef boost::function<void(int)> Fun;
   Fun fun;// 到时候用single2代替
   int n;
public:
   call_back(int a) :n(a){}
   template<typename CallBack>
   void accept(CallBack cb)
   {
       fun = cb;// 绑定回调函数
   }
   void run()
   {
       fun(n);// 执行
   }
};

int main()
{
   boost::function<int(int, int)> fun(Plus);// fun(&Plus)也可以,存储函数Plus
   assert(fun);
   cout << fun(2, 4) << endl;

   fun = 0;// 等价fun.clear(); 清空function
   assert(!fun);
   try
   {
       fun(2, 4);
   }
   catch (boost::bad_function_call& e)
   {
       if (fun.empty())cout << "fun is empty!" << endl;// fun is empty!
       cout << e.what() << endl;// call to empty boost::function
   }

boost::function<int(demo&, int, int)> fun1 = boost::bind(&demo::add, _1, _2, _3);// 函数声明时指定绑定类型和函数
cout << fun1(demo(), 4, 5) << endl;// 9

   demo d;
   boost::function<int(int, int)> fun2 = boost::bind(&demo::add, &d, _1, _2);// 在bind时绑定demo的实例和函数
   cout << fun2(4, 5) << endl;// 9

   // 引用
   boost::function<int(int)> fun3 = boost::cref(d);// 包装对象的引用
   cout << fun3(10) << endl;// 100

   vector<int> v = (assign::list_of(1), 2, 3, 4, 5, 6, 7, 8, 9, 10);
   summary<int> s;
   boost::function<void(int const&)> fun4(boost::ref(s));
   for_each(v.begin(), v.end(), fun4);// std 1^2 (1+2)^2 (1+2+3)^2 ...
   cout << s.sum << endl;// 55

   // 回调
   call_back cb(100);
   cb.accept(call_back_print);// 绑定
   cb.run();// 100

cb.accept(boost::bind(&summary<int>::print,s,_1));// 绑定
cb.run();// 10000

   cb.accept(boost::ref(s));// sum = 55
   cb.run();// (55 +100)^2
   return 0;
}

来源：CSDN

作者：ztq小天

链接：https://blog.csdn.net/weixin_38850997/article/details/88419211

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fun函数

int函数