Subj : Re: How to pass class-member function to pthread_create(....)?
To   : comp.programming.threads
From : Joe Seigh
Date : Fri Jul 15 2005 02:59 pm

Vyacheslav Kononenko wrote:
> Joe Seigh wrote:
> 
>>You'll have to use a static function (with external "C" I believe) that
>>is used as the function parameter for pthread_create.  I will have to
>>invoke the method.  The object and other parameterw will have to be passed
>>by arg.  If just object, a simple cast will do, otherwise they have to be
>>passed in a structure.
>>
>>--
>>Joe Seigh
> 
> 
> It has to match signature that "pthread_create" expects so it has to be
> static method or generic function and extern "C" is not necessary. For
> example:
> 
> class foo {
>    void thread_function();
> public:
>    static void *static_func( void * ptr) { reinterpret_cast<foo *>( ptr
> )->thread_function(); }
> };
> 
> ...
> foo *test;
> pthread_create( thread, attr, foo::thread_func, test );
> ...
> 

 void * start(void * arg) {
   ((MyObj *)arg)->func();
   return NULL;  // or something returned from func
 }

or 
 void * start(void * arg) {
    struct somestruct *args = (struct somestruct *)arg;

    args->obj->func(args->arg1, ...);
    return NULL;
 }

You have to explicitly construct the object method invocation.  And pthreads
is a *C* library.  It can't make calls to C++ methods.   If you figure out
how to do that in a portable manner in C, let the posix pthreads committee know.


-- 
Joe Seigh

When you get lemons, you make lemonade.
When you get hardware, you make software.

.