JH wrote:

Hi,

I have a derived base class:

class Base : boost::enable_shared_from_this<Base> { public: Base(); virtual ~Base(); virtual boost::shared_ptr<Base> SharedFromThis(void) {return shared_from_this();} private: }

class Derived : public Base { public: Derived(); ~Derived();

// boost::shared_ptr<Derived> SharedFromThis(void) {return boost::static_pointer_cast<Derived>(shared_from_this());} private:

};

Applications are sharing the derived class, it can either use shared_ptr<Derived> or shared_ptr<Base> by calling the SharedFromThis(), three options:

(1) Don't define derived class own SharedFromThis(), always call Base SharedFromThis() to pass shared_ptr<Base> as Derived shared_ptr, the reference count will be shared_ptr<Base>.

(2) Define derived class its own SharedFromThis() and pass shared_ptr<Derived> to applications:

boost::shared_ptr<Derived> SharedFromThis(void) {return boost::static_pointer_cast<Derived>(shared_from_this());}

That one cannot be virtual as conflicted to Base SharedFromThis(), the reference count will always be boost::shared_ptr<Derived>

(3) Mixed both boost::shared_ptr<Derived> and boost::shared_ptr<Base> in applications, that could be a bad option to cause segmentation as one shared_ptr could be ended before another shared_ptr.

Which option will be safer?

The shared_ptr<Derived> that is returned by the static_pointer_cast shares the same reference count as the original shared_ptr<Base>, so it shouldn't matter.