Hi Valery,
Just one comment for not confusing C++ beginners
by using incorrect terminology:
On Thu, 2 Mar 2000, Valeri Fine (Faine) wrote:
> TPadView3D is an abstract interface between TPad and some concrete
> 3D viewer. So it must be linked with very TPad but should impose no extra
> dependencies since all its methods look as follows:
>
> inline void TPadView3D::ExecuteEvent(Int_t, Int_t, Int_t) { }
> inline void TPadView3D::Paint(Option_t *) { }
> inline void TPadView3D::Size(Int_t, Int_t) { }
> inline void TPadView3D::PaintBeginModel(Option_t *) { }
> inline void TPadView3D::PaintEnd(Option_t *) { }
> inline void TPadView3D::PaintScene(Option_t *) { }
> inline void TPadView3D::PaintPolyMarker(TPolyMarker3D *, Option_t *) { }
> inline void TPadView3D::PaintPolyLine(TPolyLine3D *, Option_t *) { }
> inline void TPadView3D::PaintPoints3D(const TPoints3DABC *,Option_t *){ }
> inline void TPadView3D::SetAttNode(TNode *, Option_t *) { }
> inline void TPadView3D::SetLineAttr(Color_t ,Int_t ,Option_t *) { }
> inline void TPadView3D::UpdateNodeMatrix(TNode *, Option_t *) { }
> inline void TPadView3D::UpdatePosition(Double_t ,Double_t ,Double_t ,TRotMatrix *, Option_t *){ }
This is not an abstract interface as it does not contain any
abstract method. The abstract methods look like this:
> inline void TPadView3D::ExecuteEvent(Int_t, Int_t, Int_t) = 0;
> inline void TPadView3D::Paint(Option_t *) = 0;
... etc.
Making a method abstract enforces all derived classes to
provide implementation of this method. If you omit this
implementation than you will not be able to instantiate
such derived class.
(Compiler will give you error on "new MyDerivedClass" if
implementation of any abstract method is missing.)
This is used in interfaces for ensuring that all interface
implementation will provide the required methods.
Best regards,
Ivana Hrivnacova
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e-mail: Ivana.Hrivnacova@cern.ch
address: PPE Division; 160-1-016; CERN; 1211 Geneve; Switzerland
phone: (022)-767-9749
Home institute: NPI Rez near Prague, Czech Republic
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