Hi Ingo,
The output of your few lines should produce:
Warning in <TDatabasePDG::TDatabasePDG>: object already instantiated
Adress of mydatabase: 0x86a5050
Adress of mydatabase2: 0x86a0440
Instead of calling the constructor directly, we recommend the form:
TDatabasePDG *pdg = TDatabasePDG::Instance();
Rene Brun
Ingo Strauch wrote:
>
> Hi Rooters!
>
> If I understand correctly, TDatabasePDG is supposed to protect itself against
> multiple instances:
>
> ----------------------------------------------------------------------------
> TDatabasePDG::TDatabasePDG() : TNamed("PDGDB","The PDG particle data base")
> {
> // Create PDG database.
>
> fParticleList = 0;
> if (fgInstance) Warning("TDatabasePDG", "object already instantiated");
> else fgInstance = this;
> }
> ----------------------------------------------------------------------------
>
> But compiling the following code does not give me the above warning I would
> expect.
>
> ----------------------------------------------------------------------------
> #include<iostream.h>
> #include<TROOT.h>
> #include<TDatabasePDG.h>
>
> int main()
> {
> TROOT root("PDGtest", "How about multiple instances?");
> TDatabasePDG *mydatabase;
> TDatabasePDG *mydatabase2;
> mydatabase = new TDatabasePDG();
> mydatabase2 = new TDatabasePDG();
> cout << "Adress of mydatabase: " << mydatabase <<endl;
> cout << "Adress of mydatabase2: " << mydatabase2 <<endl;
>
> }
>
> ----------------------------------------------------------------------------
>
> Do I miss something??? And isn't the constructor supposed to be non-public
> (Singleton pattern by Gamma etc.)?
>
> Ciao,
> Ingo
>
> ----------------------------------------------------------------------------
> Ingo Strauch Budapester Str. 30, 20359 Hamburg, Tel.: +49 40 7421 4722
> Office: DESY, Group H1/AAC1, Room 1c354, Notkestr. 85, 22607 Hamburg
> strauch@mail.desy.de Tel. +49 40 8998 2312
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> I. Phys. Institut RWTH Aachen, Room 28B210, Sommerfeldstr. 14, 52056 Aachen
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> ----------------------------------------------------------------------------
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