执行类的成员函数 [英] Executing a member function of a class

问题描述

我试图以一种方式实验C ++ 11线程，它接受一个类的成员函数作为参数到线程构造函数，如下面的第20行标记的第一个代码片段所示。类定义在第二个代码段中给出。当这个代码编译时，我得到一堆错误显示在第三个片段。任何人都可以告诉我我做错了什么？感谢。

SNIPPET 1：主题初始化（main_app.cpp）

  #include< thread> 
 #includeServiceRegistrar.hpp
 
 #define SERVER_TYPE 100065 
 #define SERVER_INST_LOWER 1 
 #define SERVER_INST_UPPER 2 
 #define TIMEOUT 500000 
 
 int main（）
 {
 ServiceRegistrar sr1（SERVER_TYPE，TIMEOUT，SERVER_INST_LOWER，SERVER_INST_LOWER）; 
 / * LINE 20是以下* / 
 std :: thread t（& ServiceRegistrar :: subscribe2TopologyServer，sr1）; 
 t.join（）; 
 sr1.publishForSRs（）; 
 
} 
  

SNIPPET 2：类别定义

  class ServiceRegistrar 
 {
 public：
 ServiceRegistrar（int serverType，int serverTimeOut，int serverInstanceLower，int serverInstanceUpper）
：mServerType（serverType），
 mServerTimeOut（serverTimeOut），
 mServerInstanceLower（serverInstanceLower），
 mServerInstanceUpper（serverInstanceUpper）
 {} 
 
 void subscribe2TopologyServer（）; 
 void publishForSRs（）; 
 void publishForServices（）; 
 
 private：
 int mServerType; 
 int mServerTimeOut; 
 int mServerInstanceLower; 
 int mServerInstanceUpper; 
}; 
  

SNIPPET 3：编译输出

  $ g ++ -g -c -Wall -std = c ++ 11 main_app.cpp -pthread 
在/ usr / include / c ++ / 4.7 / ratio：38：0，
来自/usr/include/c++/4.7/chrono:38，
来自/usr/include/c++/4.7/thread:38, 
来自main_app .cpp：8：
 /usr/include/c++/4.7/type_traits：在实例化'struct std :: _ Result_of_impl< false，false，std :: _ Mem_fn< void（ServiceRegistrar :: *）（）> ，ServiceRegistrar>'：
 /usr/include/c++/4.7/type_traits:1857:12：required from'class std :: result_of< std :: _ Mem_fn< void（ServiceRegistrar :: *）（）> ServiceRegistrar）>'
 /usr/include/c++/4.7/functional:1563:61：需要从'struct std :: _ Bind_simple< std :: _ Mem_fn< void（ServiceRegistrar :: *）（）> ServiceRegistrar）>'
 /usr/include/c++/4.7/thread:133:9：需要从'std :: thread :: thread（_Callable&&&&& ...）[with _Callable = void（ServiceRegistrar :: *）（）; _Args = {ServiceRegistrar&}]'
 main_app.cpp：20：64：从这里需要
 /usr/include/c++/4.7/type_traits:1834:9：错误： （std :: _ Mem_fn< void（ServiceRegistrar :: *）（）>）（ServiceRegistrar）'
  

解决方案

显然它是一个 gcc 4.7 bug ... use

  std :: thread t（& ServiceRegistrar :: subscribe2TopologyServer， & sr1）; 
 
      你可能不想将 sr1 复制到 t 的thread-local-storage，所以这更好
 
I am trying to experiment the C++11 threads in a way that it accepts a member function of a class  as a parameter into the thread constructor as shown in the first code snippet below on line 20 that is marked . The class definition is given in the 2nd code snippet. When this code is compiled, I am getting a bunch of errors shown in the 3rd snippet. Can anyone tell me what I am doing wrong? Thanks.

SNIPPET 1: Thread initialization (main_app.cpp)
#include <thread>
#include "ServiceRegistrar.hpp"

#define SERVER_TYPE  100065
#define SERVER_INST_LOWER  1
#define SERVER_INST_UPPER  2
#define TIMEOUT  500000

int main()
{
  ServiceRegistrar sr1(SERVER_TYPE, TIMEOUT, SERVER_INST_LOWER, SERVER_INST_LOWER);
      /*LINE 20 is the following*/
  std::thread t(&ServiceRegistrar::subscribe2TopologyServer, sr1);
t.join();
  sr1.publishForSRs();

}
SNIPPET 2: Class definition
class ServiceRegistrar
{
  public:
    ServiceRegistrar(int serverType, int serverTimeOut, int serverInstanceLower, int serverInstanceUpper)
       : mServerType(serverType),
         mServerTimeOut(serverTimeOut),
         mServerInstanceLower(serverInstanceLower),
         mServerInstanceUpper(serverInstanceUpper)
         { }

     void subscribe2TopologyServer();
     void publishForSRs();
     void publishForServices();

  private:
     int mServerType;
     int mServerTimeOut;
     int mServerInstanceLower;
         int mServerInstanceUpper;           
  };
SNIPPET 3: Compilation output
  $ g++ -g -c -Wall -std=c++11 main_app.cpp -pthread
  In file included from /usr/include/c++/4.7/ratio:38:0,
             from /usr/include/c++/4.7/chrono:38,
             from /usr/include/c++/4.7/thread:38,
             from main_app.cpp:8:
  /usr/include/c++/4.7/type_traits: In instantiation of ‘struct    std::_Result_of_impl<false, false, std::_Mem_fn<void (ServiceRegistrar::*)()>,    ServiceRegistrar>’:
  /usr/include/c++/4.7/type_traits:1857:12:   required from ‘class std::result_of<std::_Mem_fn<void (ServiceRegistrar::*)()>(ServiceRegistrar)>’
  /usr/include/c++/4.7/functional:1563:61:   required from ‘struct std::_Bind_simple<std::_Mem_fn<void (ServiceRegistrar::*)()>(ServiceRegistrar)>’
 /usr/include/c++/4.7/thread:133:9:   required from ‘std::thread::thread(_Callable&&,  _Args&& ...) [with _Callable = void (ServiceRegistrar::*)(); _Args = {ServiceRegistrar&}]’
 main_app.cpp:20:64:   required from here
/usr/include/c++/4.7/type_traits:1834:9: error: no match for call to     ‘ (std::_Mem_fn<void (ServiceRegistrar::*)()>) (ServiceRegistrar)’

解决方案
Apparently it's a gcc 4.7 bug...use
std::thread t(&ServiceRegistrar::subscribe2TopologyServer, &sr1);
instead.

EDIT: actually, you probably don't want to be copying sr1 to the thread-local-storage of t, so this is better anyway.

                        
这篇关于执行类的成员函数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！