[Fwd: Problems in streaming a variable lenght array of TString]

From: Chiara Zampolli <Chiara.Zampolli_at_bo.infn.it>
Date: Tue, 4 Aug 2009 15:59:49 +0200

Hi,

    Sorry in case you double receive this mail... I sent it yestarday, but I'm not sure it was properly received...

    Here it is.
    Cheers,

          Chiara

---

Hi,

    I have a problem when trying to write an object containing a variable length array of TString to a file. In fact, the object contains a variable length array of different types, which are initialized only if the corresponding constructor is called.

    In the attached file you can fine the class (AliDCSArray.h/cxx) where the array is, and a macro (test1.C) to write an object of that class in a file. The TString array is not initialized, in this example, while I initialize the Bool_t one.

    Here's what I get when exectuting the macro:

    root [0] .x test1.C
    Info in <TUnixSystem::ACLiC>: creating shared library     /home/zampolli/FileDCSLHC/ForROOT/././AliDCSArray_cxx.so     Error in <TStreamerInfo::WriteBufferAux>: The pointer to element     AliDCSArray::fString type 501 (TString*) is null

    root [1] .q

I know the error is related to that: the streamer can't write the TString pointer object if it is null. But why doesn't it complain for the other types? Am I doing something wrong? Am I missing somthing? Is there a workaround? Is this not supported at all? Do I need my own streamer? :-)

Thanks, and cheers,

Chiara

#ifndef ALI_DCS_ARRAY_H
#define ALI_DCS_ARRAY_H

/* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *

• See cxx source for full Copyright notice */

/* $Id$ */

////////////////////////////////////////////////////////////////////////////////
//                                                                            //
// This class represents the value(s) of a the LHC DPs at a given timestamp   //
//                                                                            //
////////////////////////////////////////////////////////////////////////////////



#include <TObject.h>

#include <TString.h>
#include <TTimeStamp.h>

class AliDCSArray : public TObject {
 public:

	enum Type {
		kInvalid = 0,
		kBool = 1,
		kChar = 2,
		kInt = 3,
		kUInt = 4,
		kFloat = 5,
		kString = 6
	};
	
	AliDCSArray();
	AliDCSArray(const AliDCSArray& c);
	
	virtual ~AliDCSArray();
	
	AliDCSArray& operator=(const AliDCSArray& c);
	
	AliDCSArray(Int_t nentries, Bool_t* value, TTimeStamp* timeStamp);
	AliDCSArray(Int_t nentries, Char_t* value, TTimeStamp* timeStamp);
	AliDCSArray(Int_t nentries, Int_t* value, TTimeStamp* timeStamp);
	AliDCSArray(Int_t nentries, UInt_t* value, TTimeStamp* timeStamp);
	AliDCSArray(Int_t nentries, Float_t* value, TTimeStamp* timeStamp);
	AliDCSArray(Int_t nentries, TString* value, TTimeStamp* timeStamp);
	
	Int_t GetNEntries() const { return fnentries;}
	Bool_t* GetBool() const { return fBool; }
	Char_t* GetChar() const { return fChar; }
	Int_t* GetInt() const { return fInt; }
	UInt_t* GetUInt() const { return fUInt; }
	Float_t* GetFloat() const { return fFloat; }
	TString* GetString() const { return fString; }
	
	Type GetType() const { return fType; }
	
	TTimeStamp* GetTimeStamp() const { return fTimeStamp; }
	void SetTimeStamp(TTimeStamp* timeStamp) { fTimeStamp = timeStamp; }
	

 protected:         

        void Init();         

        Type fType; // type of the value stored         

	Int_t fnentries;       // n. of entries at the same timestamp
	Bool_t* fBool;         //[fnentries] bool value
	Char_t* fChar;         //[fnentries] char value
	Int_t* fInt;           //[fnentries] int value
	UInt_t* fUInt;         //[fnentries] uint value
	Float_t* fFloat;       //[fnentries] float value
	TString* fString;      //[fnentries] string value
	
	TTimeStamp* fTimeStamp;    // timestamp of this value
	
	ClassDef(AliDCSArray, 1);

};

#endif

void test1(){

	gROOT->LoadMacro("./AliDCSArray.cxx++g");
	Int_t nentries =2;
	Bool_t b[2]={kTRUE,kFALSE};
	TTimeStamp* time = new TTimeStamp(17457698);
	AliDCSArray* dcs = new AliDCSArray(nentries, b, time);

	TFile* f = new TFile("test.root","RECREATE");
	dcs->Write();
	f->Close();
	return;

} Received on Tue Aug 04 2009 - 16:04:25 CEST