Rene,
thanks for your example, I changed my class structure to this, but now when I call B.Write() I get the error "missing streamer on A dummy streamer called" which makes sense since each class should call its base class streamer and with the 0 in ClassDef A now has no streamer !
Joe
>
> From: Rene Brun <Rene.Brun@cern.ch>
> Date: Wed, 23 Jan 2002 17:05:44 +0000
> To: joer00@bellsouth.net
> CC: roottalk@pcroot.cern.ch
> Subject: Re: [ROOT] Multiple inheritance from TObject problem/ old cutoms class read/write problem
>
> I think that giving a simple example is better:
>
> //-------file joe.cxx
> #include "TObject.h"
>
> //-------------------------
> class A {
>
> private:
> int fA1;
> int fA2;
>
> public:
> A() {fA1=1;fA2=2;}
> ClassDef(A,0)
> };
>
> //-------------------------
> //class B : public A, public TObject { //<===wrong order
> class B : public TObject, public A {
>
> private:
> int fB1;
> int fB2;
>
> public:
> B() {fB1=11;fB2=12;}
>
> ClassDef(B,1)
> };
>
> ClassImp(A)
> ClassImp(B)
> //------------end of jeoe.cxx
>
> In interactive root, do
> root > .L joe.cxx++
> root > TFile f("junk.root","recreate");
> root > B b;
> root > b.Write("b");
>
> ClassDef is mandatory for all classes involved in I/O.
> Specify ClassDef(A,0) if you do not want to write the members
>
> Rene Brun
>
>
> joer00@bellsouth.net wrote:
> >
> > Rene,
> >
> > just to be 100 % sure now, from you posts this should work: (if yes just asnwer yes to save time, if no please explain because it than cotradicts with your provious posts !)
> >
> > Class A does NOT deriver from TObject, does NOT define the ClassDef macros and has NO streamer. It HAS datamemebers which I do NOT want/need to write to disk.
> >
> > Class B:public A,TObject
> >
> > DOES deriver from TObject, DOES implement ClassDef, HAS a dictionary file,HAS data members which need to be written to disk.
> >
> > BObject->Write("NAME"); and
> > BObject=(B*)SomeFile->Get("Name");
> >
> > WILL work although base class does NOT deriver from TObject and has no streamer !
> >
> > Joe
>
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