Re: [boost] dynamic_cast with WeakPtr?

Subject: Re: [boost] dynamic_cast with WeakPtr?
From: Sören Freudiger (muffmolch_at_[hidden])
Date: 2008-11-24 15:09:54

ups, sorry, my fault.. the example seems to work, but I run into that
problem because I tried to perform an dynamic_cast on that weak_ptr. How
this should be done in this simple example?

class Base    
{
public:
   boost::weak_ptr<Base> neigh;
};

class Derived : public Base
{
};

int main()
{
   {
      boost::shared_ptr<Base>    a(new Base);
      boost::shared_ptr<Derived> d(new Derived);

      a->neigh = d;
      d->neigh = a;

      //like that?
      boost::shared_ptr<Derived> pD2 = boost::shared_dynamic_cast< Derived
>( a->neigh.lock());
   }
}

-----Ursprüngliche Nachricht-----
Von: Sören Freudiger [mailto:muffmolch_at_[hidden]] 
Gesendet: Montag, 24. November 2008 21:03
An: boost_at_[hidden]
Betreff: dynamic_cast with WeakPtr?

Hi @all
Maybe you can help me. I tried to use weak_ptr for breaking circular
references, but I found out that this pointers can't handle derived classes.
But in my classes I have some neighbor relations that I want to tore with
shared_ptr:

class Base    
{
public:
  boost::shared_ptr<Base> neigh;
};

class Derived : public Base
{
};

int main()
{
   {
     boost::shared_ptr<Base>    a(new Base);
     boost::shared_ptr<Derived> d(new Derived)

     a.neigh = d;
     d.neigh = a;
   }
   //both objects are in memory because of circular references, but weak
pointer doesn't work, 
   //becaus eit seems to be unable handling derived classes... and there's
no dynamic cast
}

How do you solve problems like that with boost pointers avoiding circular
references?

Best reagrds,
  SirAnn