Hi Sue,
Your program is correct, except that you should not use the split mode
in this situation. Simply replace:
simpletree->Branch("Simple","Simple",&simple,16000,1);
by
simpletree->Branch("Simple","Simple",&simple,16000,0);
Rene Brun
Susan Kasahara wrote:
>
> Hi Rooter's,
> I am wondering if the following is possible:
> I have a class "Simple" (since this is a simplified example of what
> I'm actually trying to do) that has two data members:
> Int_t fID;
> TShape* fShape;
>
> It has a constructor:
> Simple(Int_t id, TShape* shape): fID(id), fShape(shape) { }
>
> that can be called with an object of any class that inherits from TShape, e.g.
>
> TTUBE* tube = new TTUBE("TUBE","TUBE","void",150,200,400); // TTUBE inherits from TShape
> Simple* simple = new Simple(1,tube); // invoke Simple constructor
>
> I am trying to store the Simple objects in a ROOT Tree. What I find
> is that when I fill the tree with the Simple objects, e.g.
>
> TTree *simpletree = new TTree("SimpleTree","Simple Tree");
> Simple *simple = 0;
> // Split branches to store fShape objects & fID on separate branches
> simpletree->Branch("Simple","Simple",&simple,16000,1);
> TTUBE *tube = new TTUBE("TUBE","TUBE","void",150,200,400);
> simple = new Simple(1,tube);
> simpletree -> Fill(); // store first Simple object in Tree
> ...
>
> ,that the TTree::Fill method correctly recognizes that the fShape pointer should
> invoke the TTUBE::Streamer method to write the TTUBE object to the TTree.
>
> But when I try to read the Simple object back in from the tree, e.g.:
>
> ...
> // Retrieve ROOT tree holding the data
> TTree *tree = (TTree*)file -> Get("SimpleTree");
> Simple *simple = new Simple();
> tree -> SetBranchAddress("Simple",&simple);
> nb = tree -> GetEntry(0);
> ...
>
> it does not invoke the TTUBE::Streamer method to read the TTUBE object
> back into memory, instead it invokes the TShape::Streamer method (and
> then I get an error message).
>
> Has anybody tried something similar or have any ideas on how to
> make this work? Or is this just a bad design idea, I'd appreciate input
> on that too.
> I attach the code that I'm using on a RH Linux 6.0 system using
> ROOT v2.24/02.
>
> Thanks for any help,
> Sue Kasahara
>
> #ifndef SIMPLE_H
> #define SIMPLE_H
> ///////////////////////////////////////////////////////////////////////////
> // //
> // Simple class //
> // //
> ///////////////////////////////////////////////////////////////////////////
> #include "TShape.h"
> #include <iostream.h>
>
> class Simple : public TObject {
>
> private:
> Int_t fID; // id number
> TShape* fShape; // pointer to base class shape
>
> public:
>
> Simple() : fID(0), fShape(0) { }
> Simple(Int_t id, TShape* shape): fID(id), fShape(shape) { }
> virtual ~Simple();
> virtual void Print(Option_t *option = "") const;
>
> ClassDef(Simple,1) //Simple class
> };
>
> #endif // SIMPLE_H
>
> /////////////////////////////////////////////////////////////////////////////////
> // Simple.cxx //
> /////////////////////////////////////////////////////////////////////////////////
> #include <iostream.h>
> #include "Simple.h"
>
> ClassImp(Simple)
>
> Simple::~Simple() {
> // Destructor
> if (fShape) {
> delete fShape;
> fShape =0;
> }
> }
>
> void Simple::Print(Option_t *option) const {
> // Print the contents
> cout << "fID= " << fID << endl;
> fShape -> Print();
>
> }
>
> /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
> // Driver code to open file, create tree, and write 3 Simple objects to //
> // tree. //
> ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
> #include "TROOT.h"
> #include "TFile.h"
> #include "TTree.h"
> #include "TTUBE.h"
> #include "Simple.h"
>
> TROOT test("test","Program to test simple classes");
>
> int main(int argc, char **argv)
> {
>
> // Open output file to hold events
> TFile *simplefile = new TFile("simple.root","RECREATE","Simple root file");
>
> // Create a ROOT tree to hold the simple data
> TTree *simpletree = new TTree("SimpleTree","Simple Tree");
>
> Simple *simple = 0;
> // Split branches to store fShape objects & fID on separate branches
> simpletree->Branch("Simple","Simple",&simple,16000,1);
>
> for (Int_t ient=0; ient < 3; ient++) {
> // Create 3 Simple objects containing TTube's and store each in tree
> TTUBE *tube = new TTUBE("TUBE","TUBE","void",150,200,400);
> // tube is adopted & deleted by Simple
> simple = new Simple(ient,tube);
> simple -> Print();
> simpletree -> Fill();
> delete simple;
> }
>
> // Write the simple tree to file
> simplefile->Write();
> // Print final summary of simple tree contents
> simpletree->Print();
>
> return 0;
> }
>
> ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
> // //
> // Code to open root file containing tree, Get tree, and attempt to read in //
> // 3 Simple objects from tree //
> // //
> //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
> #include "TROOT.h"
> #include "TFile.h"
> #include "TTree.h"
> #include "TTUBE.h"
> #include "Simple.h"
>
> TROOT test("test","Program to test simple classes");
>
> int main(int argc, char **argv)
> {
>
> // Open file to read Simple entries
> TFile *file = new TFile("simple.root","READ");
>
> // Retrieve ROOT tree holding the data
> TTree *tree = (TTree*)file -> Get("SimpleTree");
>
> Simple *simple = new Simple();
> tree -> SetBranchAddress("Simple",&simple);
>
> Int_t nentries = (Int_t)tree -> GetEntries();
> Int_t nb;
> for (Int_t ient=0; ient < nentries; ient++) {
> nb = tree -> GetEntry(ient);
> simple -> Print();
> }
>
> return 0;
>
> }
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