lib/factory.hpp

/*
  FACTORY.hpp  -  template for object/smart-pointer factories
 
  Copyright (C)         Lumiera.org
    2008,               Hermann Vosseler <Ichthyostega@web.de>
 
  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 2 of the
  License, or (at your option) any later version.
 
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
*/


#ifndef LUMIERA_FACTORY_H
#define LUMIERA_FACTORY_H

#include <tr1/memory>



namespace lumiera
  {
  namespace factory
    {
    template
      < class T,                     // the product to be created
        class SMP =std::auto_ptr<T> // smart-pointer actually returned
      >
    class Wrapper
        {
        protected:
          SMP wrap (T* product) { return SMP (product); }

        public:
          typedef SMP PType;
        };
    
    
    template
      < class T,                  // the product to be created
        class WR = Wrapper<T>    // used for fabricating the wrapper
      >
    class Factory :  public WR
      {
      public:
        typename WR::PType operator() () { return wrap (new T ); }
        
      };
    
    
    
    
    
    /* -- some example and default instantiiations -- */  
    
    using std::tr1::shared_ptr;

    template<class T>
    class Wrapper<T, shared_ptr<T> >
      {
      protected:
        shared_ptr<T> wrap (T* product) { return shared_ptr<T> (product); }

      public:
        typedef shared_ptr<T> PType;
      };
    
    
    template<class T>
    class RefcountPtr : public Factory<T, Wrapper<T,shared_ptr<T> > >
      {
      public:
        typedef shared_ptr<T> PType;
      };
     
    
    template
      < class T,       // Interface class
        class TImpl   // Implementation class to be created
      >
    class PImplPtr : public Factory<T, Wrapper<T> >
      {
      public:
        typedef std::auto_ptr<T> PType;
        
        PType operator() (){ return wrap (static_cast<T*> (new TImpl)); };
      };
      
      
      
  } // namespace factory

  using factory::Factory;
  
  
} // namespace lumiera
#endif

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