ServiceHandle.h

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#ifndef GAUDIKERNEL_SERVICEHANDLE_H
#define GAUDIKERNEL_SERVICEHANDLE_H

//Includes
#include "GaudiKernel/GaudiHandle.h"
#include "GaudiKernel/IMessageSvc.h"
#include "GaudiKernel/ISvcLocator.h"
#include "GaudiKernel/Bootstrap.h"
#include "GaudiKernel/GaudiException.h"
#include "GaudiKernel/MsgStream.h"
#include "GaudiKernel/ServiceLocatorHelper.h"

#include <string>
#include <stdexcept>

// class predeclarations
class IAlgTool;
class IToolSvc;
class ServiceHandleProperty;


template< class T >
class ServiceHandle : public GaudiHandle<T> {
public:
  //
  // Constructors etc.
  //
  ServiceHandle( const std::string& serviceName, const std::string& theParentName )
    : GaudiHandle<T>(serviceName, "Service", theParentName), 
      m_pSvcLocator(0), m_pMessageSvc(0)
  {}

  StatusCode retrieve() const { // not really const, because it updates m_pObject
    return GaudiHandle<T>::retrieve();
  }
  
//  /** Release the Service.
//    Function must be repeated here to avoid hiding the function release( T*& ) */
//   StatusCode release() const { // not really const, because it updates m_pObject
//     return GaudiHandle<T>::release();
//   }

protected:
  StatusCode retrieve( T*& service ) const {
    MsgStream log(messageSvc(), GaudiHandleBase::messageName());
    ServiceLocatorHelper helper(*serviceLocator(), log, this->parentName());
    return helper.getService(GaudiHandleBase::typeAndName(), true, T::interfaceID(), (void**)&service);
  }

//   /** Do the real release of the Service */
//   virtual StatusCode release( T* service ) const {
//     return service->release();
//   }

private:
  //
  // Private helper functions
  //
  ISvcLocator* serviceLocator() const { // not really const, because it may change m_pSvcLocator
    if ( !m_pSvcLocator ) {
      m_pSvcLocator = Gaudi::svcLocator();
      if ( !m_pSvcLocator ) {
        throw GaudiException("SvcLocator not found", "Core component not found", StatusCode::FAILURE);
      }
    }
    return m_pSvcLocator;
  }

  IMessageSvc* messageSvc() const { // not really const, because it may change m_pMessageSvc
    if ( !m_pMessageSvc ) {
      StatusCode sc = serviceLocator()->service( "MessageSvc", m_pMessageSvc, true );
      if( sc.isFailure() ) {
        throw GaudiException("Service [MessageSvc] not found", 
                             this->parentName(), sc);
      }
    }
    return m_pMessageSvc;
  }
  //
  // private data members
  //
  mutable ISvcLocator* m_pSvcLocator;
  mutable IMessageSvc* m_pMessageSvc;
};

template <class T>
inline std::ostream& operator<<( std::ostream& os, const ServiceHandle<T>& handle ) {
  return operator<<(os, static_cast<const GaudiHandleInfo&>(handle) );
}

#endif // ! GAUDIKERNEL_SERVICEHANDLE_H