Thread中的函式回撥方法，儲存著以後使用。

#ifndef THREAD_H_
#define THREAD_H_

#include <boost/noncopyable.hpp>
#include <functional>
#include <pthread.h>

class Thread : boost::noncopyable
{
public:
    typedef std::function<void ()> ThreadCallback;

    Thread(ThreadCallback callback);
    ~Thread();
    void
 
 start();
    void join();
    static void *runInThread(void *);

private:
    pthread_t threadId_;
    bool isRunning_;
    ThreadCallback callback_; //回撥函式
};

#endif //THREAD_H_

#include "Thread.h"

Thread::Thread(ThreadCallback callback)
: threadId_(0),
  isRunning_(false),
  callback_(std::move(callback))//move將表示式轉換為右值
 

{

}

Thread::~Thread()
{
    if(isRunning_)
    {
        pthread_detach(threadId_);
    }
}

void Thread::start()
{
    pthread_create(&threadId_, NULL, runInThread, this);
    isRunning_ = true;
}
void Thread::join()
{
    pthread_join(threadId_, NULL);
    isRunning_ = false;
}

void *Thread::runInThread(void
 
 *arg)
{
    Thread *pt = static_cast<Thread*>(arg);
    pt->callback_(); //呼叫回撥函式

    return NULL;
}

(1) 將普通函式作為回撥函式

void foo()
{
    while(1)
    {
        printf("foo\n");
        sleep(1);
    }
}

int main(int argc, char const *argv[])
{
    Thread t(&foo);

    t.start();
    t.join();

    return 0;
}

(2) 類的成員函式作為回撥函式

class Foo
{
public:
    void foo(int i)
    {
        while(1)
        {
            printf("foo %d\n", i++);
            sleep(1);
        }
    }
};


int main(int argc, char const *argv[])
{
    Foo f;
    int i = 34;
    Thread t(bind(&Foo::foo, &f, i));

    t.start();
    t.join();

    return 0;
}

(3) 組合一個新的執行緒類

class Foo
{
public:

    Foo()
    : thread_(bind(&Foo::foo, this))
    {
    }

    void start()
    {
        thread_.start();
        thread_.join();
    }

    void foo()
    {
        while(1)
        {
            printf("foo\n");
            sleep(1);
        }
    }
private:
    Thread thread_;
};

int main(int argc, char const *argv[])
{
    Foo f;
    f.start();

    return 0;
}