Re: [gtkmm] Replacing dynamic_cast<> with static_cast<> - compiler error.

[Nick Huxley <nick anvil co uk>]

On 18 Sep 2002, Murray Cumming wrote:

> On Wed, 2002-09-18 at 12:15, Paulo Pinto wrote:
> > Sorry for the naive question, but what is
> > the relation between `Glib::ObjectBase *'
> > and `Atk::Object *' ?
> 
> http://www.gtkmm.org/gtkmm2/reference/html/classAtk_1_1Object.html
> 
> It's a base class. Actually it's a virtual base class. I think I have
> learnt that static_cast<> can never be used to cast down from a virtual
> base class, so none of these dynamic_cast<>s can be changed to
> static_cast<>s.
> 

Unfortunately you are right. Since we're dealing with pointers for the
polymorphism then the compiler can't know what will be passed in so a
static_cast cannot be used. The dynamic_cast checks at run time and will
throw an exception if the cast cannot be meaningfully performed.

Nick