Re: ((Object *)NULL)->MemberFunction();
Kai-Uwe Bux wrote:
Ian Collins wrote:
jason.cipriani@gmail.com wrote:
Sorry about the subject but it's the most descriptive thing I came up
with. Is something like this safe to do:
// all objects let you get some string ID
class BaseObject {
public:
virtual const char * GetID (void) const;
Drop the C style void,
virtual const char* GetID() const = 0;
Is correct and idiomatic C++.
Well,
virtual const char * GetID (void) const = 0;
is correct C++, too.
If not idiomatic. The void serves a purpose in C, but not in C++.
return ((T *)NULL)->GetID();
}
This can not work for polymorphic objects. The object has to be
properly constructed in order to call a virtual method.
The code dereferences a null pointer. It has undefined behavior regardless
of whether the method is virtual or not and of whether the the "object"
(which does not exist) is polymorphic or not.
True, but it falls into the "probably works" box for normal member
functions that don't access any data members. But yes, it is a bad
thing to do.
--
Ian Collins.