/home/amesfoort/DAL/dal/hdf5/types/implicitdowncast.h

/* Copyright 2011-2012  ASTRON, Netherlands Institute for Radio Astronomy
 * This file is part of the Data Access Library (DAL).
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either 
 * version 3 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public 
 * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef DAL_IMPLICITDOWNCAST_H
#define DAL_IMPLICITDOWNCAST_H

#include "isderivedfrom.h"

namespace dal {

template<typename B>
class ImplicitDowncast {
public:
  ImplicitDowncast( B &base ): base(base) {}

  // the cast-operator can be templated based on return-type: just what we need!
  template<typename D> operator D&() {
    // trigger a compile error if an incompatible cast is requested
    IsDerivedFrom<D,B> type_safety;
    (void)type_safety;

    return dynamic_cast<D&>(base);
  }

private:
  B &base;
};

}

#endif