Hi ROOT'ers,
I'm starting to use nested classes for data storage, since that's
a very neat of encapsulating data types. For example
class DataTable : public TObject {
private:
TClonesArray fTable;
UInt_t fNEntries;
Float_t fSumEnergy;
Float_t fAvarageEnergy;
Flaot_t fEnergyVariance;
public:
class Data : public TObject {
private:
UInt_t fId;
Float_t fEnergy;
public:
Data(UInt_t id=0, Float_t energy=0) : fId(id), fEnergy(energy) {}
virtual ~Data() {}
UInt_t GetId() const { return fId; }
void SetId(UInt_t id) { fId = id; }
Float_t GetEnergy() const { return fEnergy; }
void SetEnergy(Float_t energy) { fEnergy = energy; }
ClassDef(Data, 1) //
};
DataTable() : fTable("DataTable::Data") {}
virtual ~DataTable() {}
Data* AddData(UInt_t id, Float_t energy) {
return new (fTable[fEntries++]) Data(id, energy);
fSumEnergy += energy;
...
}
Data* FindData(UInt_t id) {
TIter next(&fTable);
Data* data = 0;
while ((data = (Data*)next()))
if (data->GetId() == id)
return data;
return 0;
}
ClassDef(DataTable, 1) // Table of data
};
As I've pointed out earlier,
http://root.cern.ch/root/roottalk/roottalk01/1561.html
http://root.cern.ch/root/roottalk/roottalk01/1562.html
one has to do a couple of tricks to make this work.
However, there's another problem in all this, which has to do with
the MakeProject feature of TFile. When asking to make the classes
from the StreamerInfo, ROOT makes the files:
DataTable.h
DataTable::Data.h
but DataTable::Data isn't mentioned as a nested class in DataTable.h!,
so in essence DataTable::Data.h will define a namespace, not a nested
class, which I believe is the wrong behaviour. There are other
problems too, pertaining to the '::' in the class name.
So I suggest that ROOT makes a ClassDefNested(mother, child, version)
macro and maybe a ClassImpNested(mother, child) macro too, that will
take care of these things. Perhaps the dictionary for a given class
should say wether it is a nested class or not, and perhaps also have a
list of class nested in it.
Hope you find this useful.
Yours,
Christian -----------------------------------------------------------
Holm Christensen Phone: (+45) 35 35 96 91
Sankt Hansgade 23, 1. th. Office: (+45) 353 25 305
DK-2200 Copenhagen N Web: www.nbi.dk/~cholm
Denmark Email: cholm@nbi.dk
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