Pythia8Singleton.h

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//____________________________________________________________________________
/*!
 
\class    genie::Pythia8Singleton
 
\brief    Manage a single instance of pythia8
 
\author   Robert Hatcher <rhatcher \at fnal.gov>
          Fermilab
 
\created  May 15, 2024
 
\cpright  Copyright (c) 2003-2025, The GENIE Collaboration
          For the full text of the license visit http://copyright.genie-mc.org
*/
//____________________________________________________________________________
 
#ifndef _PYTHIA8SINGLETON_H_
#define _PYTHIA8SINGLETON_H_
 
#ifdef __GENIE_PYTHIA8_ENABLED__
#include "Pythia8/Pythia.h"
#endif // __GENIE_PYTHIA8_ENABLED__
 
namespace genie {
 
class Pythia8Singleton;
 
//ostream & operator << (ostream & stream, const Pythia8Singleton & pythia8_1);
 
class Pythia8Singleton
{
public:
 
  static Pythia8Singleton * Instance(void);
 
#ifdef __GENIE_PYTHIA8_ENABLED__
  Pythia8::Pythia * Pythia8() { return fPythia; }
#endif // __GENIE_PYTHIA8_ENABLED__
 
  //! print
  //void   Print (ostream & stream) const;
  //friend ostream & operator << (ostream & stream, const Pythia8Singleton & pythia8_1);
 
private:
 
  //! singleton instance
  static Pythia8Singleton * fInstance;
 
#ifdef __GENIE_PYTHIA8_ENABLED__
  mutable Pythia8::Pythia * fPythia; ///< actual Pythia8 instance
#endif // __GENIE_PYTHIA8_ENABLED__
 
  //! singleton class: constructors are private
  Pythia8Singleton();
  Pythia8Singleton(const Pythia8Singleton & cache);
  virtual ~Pythia8Singleton();
 
  //! proper de-allocation of the singleton object
  struct Cleaner {
      void DummyMethodAndSilentCompiler() { }
      ~Cleaner() {
         if (Pythia8Singleton::fInstance !=0) {
            delete Pythia8Singleton::fInstance;
            Pythia8Singleton::fInstance = 0;
         }
      }
  };
  friend struct Cleaner;
};
 
}      // genie namespace
 
#endif // _PYTHIA8SINGLETON_H_