c + +提振，在一类使用thread_group [英] C++ Boost, using thread_group in a class

问题描述

class c
{
public:
    int id;
    boost::thread_group thd;
    c(int id) : id(id) {}
    void operator()()
    {
        thd.create_thread(c(1));
        cout << id << endl;
    }


};

我创建c类。每一类对象，以处理工作创建线程。然而，当我编译这个我得到这个奇怪的消息

I created class c. Each class object creates threads in order to process the work. However I get this weird message when I compile this

：错误C2248：提振:: thread_group :: thread_group：不能访问类中声明私有成员'的boost :: thread_group

: error C2248: 'boost::thread_group::thread_group' : cannot access private member declared in class 'boost::thread_group'

此外，只承担任何递归调用的问题。

Besides, just assume is no recursive calling problems.

推荐答案

的问题是，你的code设置的方式是通过你的对象的副本创建一个新的线程。

The issue is that the way your code is set up is passing a copy of your object to create a new thread.

您所得到的错误，因为升压:: thread_group的拷贝构造函数是私有的，所以你不能复制C类的一个对象。因为默认的拷贝构造函数会尝试所有成员复制无法复制C类的一个对象，它无法复制的boost :: thread_group。因此，编译器错误。

You are getting the error because the copy constructor of boost::thread_group is private, so you cannot copy an object of class c. You cannot copy an object of class c because the default copy constructor tries to copy all members, and it cannot copy boost::thread_group. Thus the compiler error.

经典的解决方案，这将是要么编写自己的拷贝构造函数不尝试复制的boost :: thread_group（如果你真的想每次调用一个唯一的thread_group），或存储的boost :: thread_group的一些指针一种可复制（这将共享组，可能是你想要的）。

The classic solution to this would be to either write your own copy constructor that does not try to copy boost::thread_group(if you actually want one unique thread_group per call) or to store boost::thread_group in a pointer of some kind that can be copied(which would share the group, and is probably what you want).

注意：

它通常是简单的不写你自己的操作符（），只是沿着升压::功能票代替。这与做

It is usually simpler to not write your own operator(), and just pass along boost::functions instead. This would be done with

#include <boost/thread.hpp>
#include <iostream>
using namespace std;
class c
{
public:
    boost::thread_group thd;

    void myFunc(int id)
    {
        boost::function<void(void)> fun = boost::bind(&c::myFunc,this,1);
        thd.create_thread(fun);
        cout << id << endl;
    }


};

请注意，无论是在类C的共享，不管是按值在函数调用不共享过去了。

Note that whatever is in the class c is shared, and whatever is passed by value in the function call is not shared.

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