std :: thread，start线程在`this'（从类本身） [英] std::thread, start thread on `this' (from within the class itself)

问题描述

我试图创建一个类，它启动其成员方法之一的线程实例。
当我在主要做：

I'm trying to create a class which starts a thread-instance of a one of its member methods. When I do in main:

test myinstance;
std::thread mythread(myinstance);

然后编译。但使用以下结构：

then things compile. But using the following construction:

#include <stdio.h>
#include <unistd.h>
#include <thread>

class test
{
        std::thread *pt;
public:
        test()
        {
                pt = new std::thread(this);
        }

        void operator()() const
        {
                printf("thread start\n");
                sleep(5);
                printf("thread end\n");
        }
};

int main(int arg, char *argv[])
{
        test ptest;
        sleep(10);

        return 0;
}

我收到以下错误：

folkert @ here：〜$ g ++ -std = c ++ 0x test.cpp在
中包含的文件中/usr/include/c++/4.6/thread:39： 0，
从test.cpp：3：/usr/include/c++/4.6/functional：在成员函数'void std :: _ Bind_result< _Result，_Functor（_Bound_args
...）> :: __call（std :: tuple< _Args ...>&&&&&&&std :: _ Index_tuple< _Indexes
...>，typename std :: _ Bind_result< _Result，_Functor（_Bound_args
... ）> :: __ enable_if_void< _Res> :: type）[with _Res = void，_Args = {}，
int ..._ Indexes = {}，_Result = void，_Functor = test *，_Bound_args =
{}，typename std :: _ Bind_result< _Result，_Functor（_Bound_args
...）> :: __ enable_if_void< _Res> :: type = int]'：
/usr/include/c++/4.6 / functional：1378：24：从
实例化的std :: _ Bind_result< _Result，_Functor（_Bound_args ...）> :: result_type
std :: _ Bind_result< _Result，_Functor（_Bound_args
...）> :: operator（）（_ Args&& ...）[with _Args = {}，_Result = void，
_Functor = test *，_Bound_args = {}，std :: _Bind_result< _Result，_Functor（_Bound_args ...）> :: result_type = void] '/usr/include/c++/4.6/thread:117:13：实例化为'void
std :: thread :: _Impl< _Callable> :: _ M_run（）[with _Callable =
std :: _bind_result]'test.cpp：28：1：从
实例化这里/usr/include/c++/4.6/functional:1287:4：错误：
'（（std :: _ Bind_result *）this） - > std :: _ Bind_result :: _ M_f'不能用作函数

folkert@here:~$ g++ -std=c++0x test.cpp In file included from /usr/include/c++/4.6/thread:39:0, from test.cpp:3: /usr/include/c++/4.6/functional: In member function 'void std::_Bind_result<_Result, _Functor(_Bound_args ...)>::__call(std::tuple<_Args ...>&&, std::_Index_tuple<_Indexes ...>, typename std::_Bind_result<_Result, _Functor(_Bound_args ...)>::__enable_if_void<_Res>::type) [with _Res = void, _Args = {}, int ..._Indexes = {}, _Result = void, _Functor = test*, _Bound_args = {}, typename std::_Bind_result<_Result, _Functor(_Bound_args ...)>::__enable_if_void<_Res>::type = int]': /usr/include/c++/4.6/functional:1378:24: instantiated from 'std::_Bind_result<_Result, _Functor(_Bound_args ...)>::result_type std::_Bind_result<_Result, _Functor(_Bound_args ...)>::operator()(_Args&& ...) [with _Args = {}, _Result = void, _Functor = test*, _Bound_args = {}, std::_Bind_result<_Result, _Functor(_Bound_args ...)>::result_type = void]' /usr/include/c++/4.6/thread:117:13: instantiated from 'void std::thread::_Impl<_Callable>::_M_run() [with _Callable = std::_Bind_result]' test.cpp:28:1: instantiated from here /usr/include/c++/4.6/functional:1287:4: error: '((std::_Bind_result*)this)->std::_Bind_result::_M_f' cannot be used as a function

所以我的猜测是，它不会工作这种方式。
现在的问题是：我怎么能使用std :: thread让一个类启动一个自己方法的线程？

So my guess is that it won't work this way. My question now is: how can I, using std::thread, let a class start a thread of one of its own methods?

推荐答案

std :: thread 的构造函数之一如下所示：

One of std::threads constructors looks like this:

template<typename Callable>
    explicit thread(Callable func);

这需要您传递可调用可以使用 operator（）调用。您传递给 std :: thread 的是不可调用的。

This requires you to pass something that is callable, that means it can be invoked with operator(). What you're passing to your std::thread is not callable.

您不能调用 this 。 此是指向当前对象的指针，不可调用。

You cannot call this. this is a pointer to the current object, it is not callable.

您需要传递成员函数函数添加到你的 std :: thread 构造函数中。

You need pass a member function or other function into your std::thread constructor.

你也可以创建一个函子，可调用。

You could also create a functor and pass that, as that is callable.

编辑：只是注意到确实重载了 operator（），调用它，你做了：

Just noticed have indeed overloaded operator(), to call it, you have do the follwowing:

  test t;
  std::thread my_thread(t); //invokes operator() on test.

//also remove this statement from your ctor:  pt = new std::thread(this);

这篇关于std :: thread，start线程在`this'（从类本身）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！