Re: Problem with the Streamer function of a class derived from TDirectory...

I have modified my LinkDef file, recompiled everything, regenerated the root file and I got the same error:

Error in <TBufferFile::ReadBuffer2>: class: TUUID, attempting to access a wrong version: 127, object skipped at offset 87 Error in <TFile::ReadBuffer>: error reading all requested bytes from file file.root, got 0 of 2687036
(class TObject*)0x8346328

The autogenerated code for the Streamer function is the following:

void QMyDir::Streamer(TBuffer &R__b)
{

   // Stream an object of class QMyDir.

   if (R__b.IsReading()) {

      R__b.ReadClassBuffer(QMyDir::Class(),this);    } else {

      R__b.WriteClassBuffer(QMyDir::Class(),this);    }
}

Thank you
Pierre-Luc Drouin

Philippe Canal wrote:
> Hi Pierre-Luc,
>
> Can you try after enabling the new I/O?
> i.e:
> #pragma link C++ class QMyDir+;
>
>
> Cheers,
> Philippe.
>
> -----Original Message-----
> From: owner-roottalk_at_root.cern.ch [mailto:owner-roottalk_at_root.cern.ch] On
> Behalf Of Pierre-Luc Drouin
> Sent: Tuesday, March 18, 2008 10:27 AM
> To: Rene Brun
> Cc: roottalk_at_root.cern.ch
> Subject: Re: [ROOT] Problem with the Streamer function of a class derived
> from TDirectory...
>
> Hi,
>
> I have installed 5.18/00 (I was using 5.14/00e before) and I have
> derived my class from TDirectoryFile. The code of my class is now the
> following:
>
> #include "Rtypes.h"
> #include "TObject.h"
> #include "TDirectoryFile.h"
>
> class QMyDir: public TDirectoryFile
> {
> public:
> QMyDir():TDirectoryFile(){}
>
> QMyDir(const QMyDir& newqds):TDirectoryFile(){}
>
> QMyDir(const char *name, const char *title, TDirectory* motherDir =
> 0):TDirectoryFile(name,title,"QMyDir",motherDir){}
>
> virtual ~QMyDir(){}
>
> QMyDir& operator=(const QMyDir &rhs){fprintf(stderr,"Warning:
> TDirectoryFile::operator= cannot be called from derived class
> QMyDir\n"); return *this;}
>
> private:
>
> ClassDef(QMyDir,1) //QSigEx Data Structure Class
> };
>
> I still get an error when I try to load the instance from the file. I
> have stored and have tried to load the instance using the code I have
> shown in my previous email. Here is the error I get:
>
> _file0->Get("dir")
> Error in <TBufferFile::ReadBuffer2>: class: TUUID, attempting to access
> a wrong version: 127, object skipped at offset 87
> Error in <TFile::ReadBuffer>: error reading all requested bytes from
> file file.root, got 0 of 2687036
> (class TObject*)0x8345fa8
>
> Thank you
> Pierre-Luc Drouin
>
> Rene Brun wrote:
>
>> Pierre-Luc,
>>
>> Instead of TDirectory, you should derive from TDirectoryFile. In
>> version 5.16, TDirectory
>> became an abstract interface. See 5.16 Release Notes at:
>> http://root.cern.ch/root/Version516.news.html
>>
>> Rene Brun
>>
>> Pierre-Luc Drouin wrote:
>>
>>> Hi,
>>>
>>> I have derived a class from TDirectory and I am trying to store and
>>> retrieve an instance of this class to/from a ROOT file.
>>>
>>> I am using the autogenerated Streamer function and when I call
>>> TDirectory
>>> <http://root.cern.ch/root/html514/src/TDirectory.cxx.html#OUS8P>(const
>>> char *name, const char *title, Option_t
>>> <http://root.cern.ch/root/html514/ListOfTypes.html#Option_t>
>>> *classname, TDirectory
>>> <http://root.cern.ch/root/html514/TDirectory.html>* initMotherDir)
>>> from the constructor of my class, I set classname to the name of my
>>> class.
>>>
>>> I do not get any warning/error message when I Write the instance in
>>> the root file, but I get the following error when I try to load the
>>> instance using TFile::Get:
>>>
>>> Error in <TBuffer::ReadVersion>: Could not find the StreamerInfo with
>>> a checksum of 0 for the class "TUUID" in file.root.
>>> Error in <TBuffer::CheckByteCount>: object of class TUUID read too
>>> few bytes: 22 instead of 898023151
>>> Error in <TBuffer::CheckByteCount>: Byte count probably corrupted
>>> around buffer position 85:
>>> 898023151 for a possible maximum of 17
>>> SysError in <TFile::Seek>: cannot seek to position 60235645022633984
>>> in file file.root, retpos=-1 (Invalid argument)
>>> Error in <TFile::ReadBuffer>: error reading all requested bytes from
>>> file file.root, got 186 of 2687036
>>>
>>> Here is the code of a class that allows to reproduce the problem:
>>>
>>> class QMyDir: public TDirectory
>>> {
>>> public:
>>> QMyDir():TDirectory(){}
>>>
>>> QMyDir(const QMyDir& newqds):TDirectory(){*this=newqds; }
>>>
>>> QMyDir(const char *name, const char *title, TDirectory* motherDir
>>> = 0):TDirectory(name,title,"QMyDir",motherDir){}
>>>
>>> virtual ~QMyDir(){}
>>>
>>> QMyDir& operator=(const QMyDir &rhs){fprintf(stderr,"Warning:
>>> TDirectory::operator= function is private and cannot be called by
>>> derived class QMyDir\n"); return *this;}
>>>
>>> private:
>>>
>>> ClassDef(QMyDir,1) //QSigEx Data Structure Class
>>> };
>>>
>>> Here is the code of the autogenerated Streamer function:
>>>
>>> void QMyDir::Streamer(TBuffer &R__b)
>>> {
>>> // Stream an object of class QMyDir.
>>>
>>> UInt_t R__s, R__c;
>>> if (R__b.IsReading()) {
>>> Version_t R__v = R__b.ReadVersion(&R__s, &R__c); if (R__v) { }
>>> TDirectory::Streamer(R__b);
>>> R__b.CheckByteCount(R__s, R__c, QMyDir::IsA());
>>> } else {
>>> R__c = R__b.WriteVersion(QMyDir::IsA(), kTRUE);
>>> TDirectory::Streamer(R__b);
>>> R__b.SetByteCount(R__c, kTRUE);
>>> } }
>>>
>>> Now how I get the error in CINT:
>>>
>>> root [0] TFile file("file.root","recreate")
>>> root [1] QMyDir* dir=new QMyDir("dir","dir")
>>> root [2] file.ls()
>>> TFile** file.root
>>> TFile* file.root
>>> QMyDir* dir dir
>>> KEY: QMyDir dir;1 dir
>>> root [3] file.Write()
>>> (Int_t)0
>>> root [4] file.Close()
>>> root [5] .q
>>>
>>> root [0] TFile file("file.root","read")
>>> root [1] file.ls()
>>> TFile** file.root
>>> TFile* file.root
>>> KEY: QMyDir dir;1 dir
>>> root [2] QMyDir *dir=file.Get("dir")
>>> Error in <TBuffer::ReadVersion>: Could not find the StreamerInfo with
>>> a checksum of 0 for the class "TUUID" in file.root.
>>> Error in <TBuffer::CheckByteCount>: object of class TUUID read too
>>> few bytes: 22 instead of 898023151
>>> Error in <TBuffer::CheckByteCount>: Byte count probably corrupted
>>> around buffer position 85:
>>> 898023151 for a possible maximum of 17
>>> SysError in <TFile::Seek>: cannot seek to position 60235645022633984
>>> in file file.root, retpos=-1 (Invalid argument)
>>> Error in <TFile::ReadBuffer>: error reading all requested bytes from
>>> file file.root, got 186 of 2687036
>>>
>>>
>>> Thanks!
>>> Pierre-Luc Drouin
>>>
>>>
>>>
>
>
>
Received on Tue Mar 18 2008 - 16:50:10 CET