class Geom : public RefCount
{
...
protected:
/// Notifies this geom that it's now the child of another geom
virtual void AttachNotify(const Vector3& relative_pos, const D3DXQUATERNION& relative_rotation)=0;
protected:
/// Notifies this geom that it just got detached from its parent
virtual void DetachNotify()=0;
...
}
class GeomTranslate : public Geom
{
...
}
GeomTranslate::GeomTranslate(... Geom* child, ...)
{
...
// This code actually is the one I want
child->AttachNotify(...);
// This is the one I just added for verifying
((Geom*)this)->AttachNotify(...);
...
};
C++ inheritance weirdness
Author
Hi all,
I am just totally confused by my compiler (MSVC++ .NET 2003). I just don't know if I'm simply being stupid now or if my compiler just spits out garbage. I do C++ for some years now so I'd expect myself to know a bit about inheritance...
Here the problem:
Well its a pure virtual function. There's nothing to call. You need to define it first. I'm surprised the compiler would even letyou try to instatiate your class.
You shouldn't be able to create classes with pure virtual methods.
Cheers
Chris
You shouldn't be able to create classes with pure virtual methods.
Cheers
Chris
Author
Sorry, forgot to include the function definition of GeomTranslate::AttachNotify(). It's there indeed:
class GeomTranslate : public Geom{...protected: /// Notifies this geom that it's now the child of another geom virtual void AttachNotify(const Vector3& relative_pos, const D3DXQUATERNION& relative_rotation);protected: /// Notifies this geom that it just got detached from its parent virtual void DetachNotify();...}
Your also calling it from a constructor. Don't do that. wait until your object is fully constructed before calling base class methods. Your just playing with fire otherwise.
Cheers
Chris
Cheers
Chris
Author
Hm. The first call doesn't do a function call on itself, so that shouldn't be a problem there...
Well for the first call you can't call the a geom's appendchild method because you don't have access rights to it. That class can only do it for itself, not for other types of the same class.
Hope that helps
Cheers
Chris
Hope that helps
Cheers
Chris
GeomTranslate inherit Geom, but that does not make instances of GeomTranslate to access protected (or private) members of other instances of Geom. You can access the protected ones in your own instance but not in other instances.
EDIT: Damn, chollida1 beat me by a couple of seconds... ;)
EDIT: Damn, chollida1 beat me by a couple of seconds... ;)
Interesting one. I didn't know the answer to this myself so I googled and found this.
It says that according to the standard access to a protected member may only be made through an object or pointer- or reference-to the derived class. So if you passed in a GeomTranslate pointer, reference or object you'd be OK, but accessing it from a Geom pointer is not allowed.
Just to make clear - the above two posters are wrong. If the class has access rights then it can use those access rights for any instance of its own class, not just its own instance. I was suprised when I first learned this, but it can be useful.
Having made the above assertion I'm going to retract it again since I can't actually think of a way to test it at the moment and I am becoming less certain of its accuracy.
And just to see how many times I can edit this post before getting an edit timestamp I just thought of a way to test it and am able to make the assertion again:
Just to make clear - the above two posters are wrong. If the class has access rights then it can use those access rights for any instance of its own class, not just its own instance. I was suprised when I first learned this, but it can be useful.
Enigma
It says that according to the standard access to a protected member may only be made through an object or pointer- or reference-to the derived class. So if you passed in a GeomTranslate pointer, reference or object you'd be OK, but accessing it from a Geom pointer is not allowed.
Just to make clear - the above two posters are wrong. If the class has access rights then it can use those access rights for any instance of its own class, not just its own instance. I was suprised when I first learned this, but it can be useful.
Having made the above assertion I'm going to retract it again since I can't actually think of a way to test it at the moment and I am becoming less certain of its accuracy.
And just to see how many times I can edit this post before getting an edit timestamp I just thought of a way to test it and am able to make the assertion again:
Just to make clear - the above two posters are wrong. If the class has access rights then it can use those access rights for any instance of its own class, not just its own instance. I was suprised when I first learned this, but it can be useful.
class Base{};class Mid : public Base{ protected: void function();};void Mid::function(){}class Derived : public Mid{ public: Derived(); Derived(Derived* m);};Derived::Derived(){}Derived::Derived(Derived* m){ m->function();}int main(){ Derived d; Derived d2(&d);}Enigma
Author
Very interesting indeed. Unfortunately passing a GeomTranslate is no option here. So I could probably delegate that function call to the base class, couldn't I?
This topic is closed to new replies.
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