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Boost::thread - problems with inheritance

Mercenarey · 2013-08-03T19:02:44

I have made a class to launch threads like this:#include <boost/thread.hpp>class BaseThreadObject{ protected://---------- Protected Properties ----------------- boost::thread* m_thread;//------------ Protected Methods ------------------ public://-- Constructors, Destructor & Support Methods --- BaseThreadObject(); virtual ~BaseThreadObject(); void Startup(); void Shutdown(); //-------- Get's -------------------------- //-------- Set's --------------------------//---------- Public Methods ----------------------- void operator()(); virtual void ThreadMain() = 0;};// ------------------------------------------------// ------------------------------------------------// ------------------------------------------------void BaseThreadObject::operator()(){ ThreadMain();}// ------------------------------------------------// ------------------------------------------------// ------------------------------------------------void BaseThreadObject::Startup(){ m_thread = new boost::thread(boost::ref(*this));// m_thread = new boost::thread(*this);}// ------------------------------------------------// ------------------------------------------------// ------------------------------------------------void BaseThreadObject::Shutdown(){ m_thread->join();}// ------------------------------------------------// ------------------------------------------------// ------------------------------------------------void BaseThreadObject::ThreadMain(){ // whatever}The Startup launches the thread with the class as a ref, to prevent it from being copied (boost takes 10(!!) copies when launching). Also, I hoped that with a ref, that I could have preserved the inheritance, so I could call derived classes through virtual methods.However, when I call a virtual method, even if it is implemented in the base class, like the operator()() calls ThreadMain() (which I hoped I could then freely derive for new classes, while preserving basic threading functionality in this baseclass alone), it will fail with this message:"Unhandled exception at 0x00000000 in [prog-name].exe: 0xC0000005: Access violation reading location 0x00000000"I have similar problems when I don't use the ref and allows it to copy. It will only copy the class, that is directly inputted, not the classes it derives from.Is there any way I can create a class like this with boost, that retains an inheritance structure?

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Started by Mercenarey June 24, 2010 06:46 AM

10 comments, last by GoldenArm 10 years, 8 months ago

larryp7639

100

June 25, 2010 11:13 PM

Quote:Original post by Red Ant
I'm suspecting that no matter how much you try to cheat by using boost::ref to pass a functor to boost::thread's constructor, internally it will still at some point make a copy of the functor, and when that happens, it won't have a clue that you're really passing a derived thread object and not a BaseThreadObject. Hence it will store a copy of the BaseThreadObject part of the class instance you're passing it. The result -> slicing (google it).

I suggest the following.

*** Source Snippet Removed ***

But beware that you may run into object life time issues if your BaseThreadObject instance gets deleted while your thread is still running (and hence potentially accessing your BaseThreadObject instance).

Thanks you for the post.

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GoldenArm

149

August 03, 2013 07:02 PM

You guys are genius !!! Was struggling with getting my thread encapsulation done properly, that functor method in a struct of a base class did the job !!!

thanks

Boost::thread - problems with inheritance

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