boost库 bind/function的使用

Boost::Function 是对函数指针的对象化封装，在概念上与广义上的回调函数类似。相对于函数指针，function除了使用自由函数，还可以使用函数对象，甚至是类的成员函数，这个就很强大了哈

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

using namespace std;

class TestA
{
    public:
        void method()
        {
            cout<<"TestA: method: no arguments"<<endl;
        }

        void method(int a, int b)
        {
            cout<<"TestA: method: with arguments"
                <<"value of a is:"<<a
                <<"value of b is "<<b <<endl;
        }
};

void sum(int a, int b)
{
    int sum = a + b;
    cout<<"sum: "<<sum<<endl;
} 

int main()
{
    boost::function<void()> f;
    TestA test;

    f = boost::bind(&TestA::method, &test);
    f();

    f = boost::bind(&TestA::method, &test, 1, 2);
    f();

    f = boost::bind(&sum, 1, 2);
    f();
}

2. 应用：Thread封装

在实现自定义的线程类时，曾经这么干过：定义虚函数run()，用户自定义的CustomThread::Thread后，自己实现run()函数就OK了。 当时觉得这么做也不错。

现在有了boost::function/boost::bind我们可以这么干：

定义一个线程类：
.h文件

#include <pthread.h>
#include <string>
#include <boost/function.hpp>
#include <boost/bind.hpp>

using namespace std;
class Thread
{
    typedef boost::function<void()> ThreadFun;
    public:
        Thread(const ThreadFun& threadFun,const string& threadName = string());
        pid_t     getThreadId();
        string    getThreadName();
        int       start();

    private:
        static void* startThread(void* thread);

    private:
        pthread_t   m_thread; //线程句柄
        pid_t       m_tid;    //线程ID
        string      m_strThreadName;    //线程名称
        bool        m_bStarted;         //线程是否启动
        ThreadFun   m_func;             //线程处理函数
};

.cpp

#include "thread.h"

Thread::Thread(const Thread::ThreadFun& threadFun, const string& threadName):
m_func(threadFun), m_strThreadName(threadName)
{
}

int Thread::start()
{
    m_tid = pthread_create(&m_thread, NULL, &startThread, this);
    return 0;
}

void* Thread::startThread(void* obj)
{
  Thread* thread = static_cast<Thread*>(obj);
  thread->m_func();
  return NULL;
}

pid_t Thread::getThreadId()
{
    return m_tid;
};

string  Thread::getThreadName()
{
    return m_strThreadName;
}

void ThreadProcess()
{
    int count = 100;
    for (int i = 0; i < count; i++)
    {
        if (i % 10 == 0)
        cout<<"\n";
        cout<<i<<"\t";
    }
}

int main()
{
    boost::function<void()> f;
    f = boost::bind(&ThreadProcess);
        Thread thread(f, "ThreadTest");
        thread.start();
    sleep(1000*1000);
    return 0;
}