Q1: how to 'construct' events during reading from TFile ?
I want to keep in the *.root file a 'partially constructed' event
and add (generate) some fields while reading.
==>
Q2: Is there a method in TObject that called just after reading from
buffer (i.e. virtual void TObject::Validate()) ?
Let me explain - what I mean ...
Here - a truncated version of my Event class. I try to design it
for conversion from DST files to TTree and I want use it for 'inspecting'
events in ROOT framework.
class CMD2Event : public TObject {
private:
CMD2EventHeader fHead; // CMD2 Event header
Float_t fBeamEnergy;
Float_t fXBeam;
Float_t fYBeam;
TClonesArray *fVertecies; // List of recon. vertecies
TClonesArray *fTracks; // List of recon. tracks
TClonesArray *fZClusters; // List of recon. Z-clusters
TClonesArray *fCSIClusters; // List of recon. CsI clusters
TClonesArray *fBGOClusters; // List of recon. BGO clusters
protected:
TClonesArray *fPhotons; // Reconstructed photons
TClonesArray *fCharged; // Reconstructed charged particles
public:
TDecayMask *fDecay; // Assumed Decay Mask
TSortedList *fCombinations; // Sorted (by xi2) list of combinations
public:
CMD2Event();
virtual ~CMD2Event();
void MatchDecay() { // Do the kinematic reconstruction
if(fDecay) { fCombinations = fDecay->Match(*this);};
};
void SetFromZEBRA(); // Fill the event from ZEBRA storage
void SetEvent() { SetFromZEBRA(); MatchDecay(); };
void SetDecayMask(TDecayMask *m) { fDecay = m; MatchDecay(); };
void SetBeam(Float_t e,Float_t x=0, Float_t y=0) {
fBeamEnergy = e;
fXBeam = x;
fYBeam = y;
MatchDecay();
};
TDecayMask* GetDecayMask() { return fDecay; };
TSortedList* GetDecays() { return fCombination; };
Float_t BeamEnergy() { return fBeamEnergy; };
Float_t XBeam() { return fXBeam; };
Float_t YBeam() { return fYBeam; };
ClassDef(CMD2Event,1) // CMD2 Event
};
The central part (for analysis) - fields 'fDecay' and 'fCombinations'.
'fDecay' is a pointer to some global var. like
gDecay = TDecayMask("phi -> K+ K-") or
gDecay = TDecayMask("phi -> omega pi0, omega -> pi+ pi- pi0")
with other 'internals' concerning - how to match to 'event'.
'fCombinations' - list of TDecay combinations to reflect links
between 'pi0' and 'measured' photons. This class should export smth like
decay->Particle("omega")->Energy() and so on.
The idea :
Before writing 'events' - set fDecay and fCombination to 0 to keep disk space.
Before reading - set gDecay, tune the 'internals' and
loop over events to fill histos. But for this, I need to place smth like
if( !fDecay && gpDecay ) { fDecay = gpDecay; MatchEvent(); } into ...
what ??? (my opinion: the best place - Event::Validate() in Event.C)
For reading from FZ-file - the problem solved with a SetEvent method.
How to do in case of TFile ?
If I need to rewrite the Streamer method,
how to generate 'default' version of Event::Streamer ?
(I look into EventCint.C, but see only some CINT internal names)
And how to automate this ? ( the only thing that I need - to add
the call to Validate(b.ReadVersion()) just after 'standard' staff, that
changes with time ... )
Is there other way (may be more simple) for the same things ?
Sorry for this long long Q2 !!! (and for my ugly English ...)
Thanks in advance.
Nikolay Root
BINP, Novosibirsk
email : nroot@inp.nsk.su