Hi, and sorry for the probable newbieness of this question! I want to put weak_ptr into a piece of memory previously allocated. this is my code: // construct a weak_ptr from a share_ptr boost::weak_ptr<Obj>* cameraPtr = new boost::weak_ptr<Obj>(obj_share_ptr); // lua_newuserdata allocs memory and returns a pointer to it, just like malloc. boost::weak_ptr<Obj>* camera = static_cast<boost::weak_ptr<Obj>*>(lua_newuserdata(pLuaState,sizeof(boost::weak_ptr<Obj>))); Now i want camera to be a weak_ptr of ObjPtr. I tried different ways to do this, such as *camera = boost::weak_ptr<Obj>(obj_share_ptr); or camera->swap(*cameraPtr); or *camera = *cameraPtr; I think none of these work because in fact they all do a swap() between camera and cameraPtr. Since camera is just an malloc, it will try to swap dirty memory and segfault sometimes (yes, sometimes this worked). Out of desperation, i did this: memcpy(camera,cameraPtr,sizeof(boost::weak_ptr<Obj>)); Which seems to work but it stinks. It's copying an object with memcpy instead of using its constructor. Is there a better way to do this? Thanks, Tiago Alves