Re: [Boost-users] create threads from within a class

From: Paul Davis (pjdavis_at_[hidden])
Date: 2006-09-27 12:22:35

You need a global wrapper function.

Ie, a thread start function that takes the address of the instance of the
class as the void* pointer and then runs some method in the class.
(Generally a run method or something similar)

something like:

void* start_thread( void* data )
{
    TestThread* tt = dynamic_cast<TestThread*>( data )

   tt->run() ;

}

Paul

On 9/27/06, Monica Gretzer <mogr_progr_at_[hidden]> wrote:
>
> Hi,
>
> I want to use boost::thread to create threads that are member functions
> within a class. In all the examples I have seen, the thread function is
> defined globally.
>

I explain it with code. The following test code works:
>
> //  code 1: example program that works
> -----------------------------------------------
> #include <boost/thread/thread.hpp>
> #include <iostream>
> using namespace std;
>
> void testing()
> {
>     cout << "I'm a thread." << endl;
> }
>
> int main(int argc, char* argv[])
> {
>      // start a new thread that calls the "testing" function
>      boost::thread my_thread(&testing);
>      // wait for the thread to finish
>      my_thread.join();
>
>     return 0;
> }
>
> //
> -------------------------------------------------------------------------------------------
>
> Now, I want to create something like:
>
> // code 2: thread created from member class (code yields compiler errors)
>
> #include <boost/thread/thread.hpp>
> #include <iostream>
> using namespace std;
>
> class TestThread
> {
> public:
>    void testing(void);
>    void CreateThread(void);
> };
>
> void TestThread::CreateThread()
> {
>     // start a new thread that calls the "testing" function
>     boost::thread my_thread(&testing);
>     // wait for the thread to finish
>     my_thread.join();
> }
>
> int main(int argc, char* argv[])
> {
>     TestThread t;
>     t.CreateThread();
>
>     return 0;
> }
>
> When compiling the code above (code 2), I get the following compilation
> error:
> ISO C++ forbids taking the address of an unqualified or paranthesized
> non-static member function to form a pointer to member function. Say
> &TestThread::testing.
>
> My question is: How do I create threads from within a C++ class member
> function?
>
> Thanks a lot for your help.
>
> / Mogr
>
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