Re: [ROOT] Shared function library.

From: Christian Holm Christensen (cholm@hehi03.nbi.dk)
Date: Wed Oct 25 2000 - 08:24:52 EDT

  • Next message: Jens Ivar Jordre: "Re: [ROOT] Shared function library." 

    Hi Jens-Ivar, 

Global variables is frowned upon in BRAT. Rather, you should use
static members. For example, see BrDectectorTable, all the managers
and so on. In fact, this will solve your problem in a much simpler way
then using "R__EXTERN" and "#pragma link C++ global". 

Here's a small example

       #include <iostream.h>

       class Analyser {
       private:
         static Analyser* fgInstance; // The static instance
         static Int_t     fgInteger;  // static integer (sort of global)
       public:          
	 Analyser() { fgInstance = this; }
         
	 static Analyser* Instance() { 
           if (!fgInstance) fgInstance = new Analyser; return fgInstance; }
	 static Int_t& GetInteger() const { return fgInteger; }  
       }

       Analyser* Analyser::fgInstance  = 0;
       Int_t     Analyser::fgInteger   = 1;

       main() {
         if (Analyser::GetInteger() == 1) 
	   cout << "Good" << endl;

	 Analyser::GetInteger() = 10;
  
         Analyser* analyser = Analyser::Instance(); 

         if (analyser->GetInteger() == 10) 
	   cout << "Also good" << endl;

         analyser->GetInteger() = 5; 

         if (Analyser::GetInteger() == 5) 
	   cout << "Still good" << endl;
       } 

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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