Re: [Boost-users] Boost shared pointers, PThreads and void* casts

19 Dec 2007


      STenyaK (Bruno Gonzalez) [stenyak@gmail.com] wrote:
...
On 12/19/07, Andrew Holden  wrote:
...
typedef shared_ptr<MyClass> pMyClass;
void* MyClass::actionThread(void *objectPointer)
{
    MyClass * _obj = static_cast(objectPointer);
    pMyClass obj = _obj->shared_from_this();
    obj->action(false);
}
void MyClass::action(bool threaded)
{
    if (threaded)
    {
        pthread_t tid;
        pthread_create(&tid, 0, actionThread, this)
    } else {
        //TODO: actually perform the action
    }
}
----------------------------
This works because shared_from_this is specifically designed to allow
member functions of a class to recover the shared pointer to the
object.
Just in case... actionThread is a static method of the class, since
otherwise C++ won't allow me to get a pointer of it (and i dislike
global functions). Does this fact have any implications in the last
proposed code sample?
Not really.  actionThread is still a member function of MyClass, which
means it has full access to MyClass's members (as long as it has access
to a MyClass object somehow), including private and protected members,
and protected members from base classes.  _obj is a valid pointer to a
MyClass, so there is nothing wrong with actionThread calling _obj's
shared_from_this function.