如何从 main ( ) 调用线程成员 function

Question

I'm getting errors while compiling a program that uses threads. Here is the part that is causing problems.It would be nice if anybody told me if I'm calling the thread function in the right way.

In main.cpp:

int main() 
{
    WishList w;
    boost::thread thrd(&w.show_list);
    thrd.join();
}

In another_file.cpp:

class WishList{
public:
      void show_list();
}

void WishList::show_list(){
        .
        .
        .
        .
}

I'm getting the following error

error: ISO C++ forbids taking the address of a bound member function to form a pointer to member function.  Say ‘&WishList::show_list’

/home/sharatds/Downloads/boost_1_46_1/boost/thread/detail/thread.hpp: In member function ‘void boost::detail::thread_data<F>::run() [with F = void (WishList::*)()]’:

/home/sharatds/Downloads/boost_1_46_1/boost/thread/detail/thread.hpp:61:17: error: must use ‘.*’ or ‘->*’ to call pointer-to-member function in ‘((boost::detail::thread_data<void (WishList::*)()>*)this)->boost::detail::thread_data<void (WishList::*)()>::f (...)’, e.g. ‘(... ->* ((boost::detail::thread_data<void (WishList::*)()>*)this)->boost::detail::thread_data<void (WishList::*)()>::f) (...)’

EDIT: Having problems installing Boost library for threads. Shall try this as soon as it works

Answer 1

The syntax to take the address of a member function is &ClassName::FunctionName , so it should be &WishList::show_list , but now you need an object to call the function pointer on. Best (and easiest) is to use boost::bind :

#include <boost/bind.hpp>

WishList w;
boost::thread t(boost::bind(&WishList::show_list, &w));

Answer 2

Nothing to do with threads, this is just "how do I obtain a pointer to a member function". Do what the compiler says, say &WishList::show_list . But you may also need to pass the instance pointer along.

Update: Yes, use bind like Xeo says.

Regarding your title: Note that the function does not "belong to the thread". Classes are not part of threads. All threads access the same memory -- each thread has its own space for automatic storage, but there's nothing in a class definition that says "this goes in a separate thread".