return_base_tag.h

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// Copyright (c) 2006  INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); 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; version 2.1 of the License.
// See the file LICENSE.LGPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/CGAL-3.3-branch/Kernel_23/include/CGAL/Kernel/Return_base_tag.h $
// $Id: Return_base_tag.h 33348 2006-08-16 14:56:11Z spion $
// 
//
// Author(s)     : Sylvain Pion

#ifndef CGAL_KERNEL_RETURN_BASE_TAG_H
#define CGAL_KERNEL_RETURN_BASE_TAG_H

#include <CGAL/basic.h>

// This is a simple tag which is used as additional (first) argument in
// some kernel functors, to tell them to return the base (rep) class,
// instead of the main type (e.g. Kernel_base::Point_2 instead
// of Kernel::Point_2).  This is a minor optimization which prevents
// useless copies of the "reps".

// Those functors are only those used in the constructors of the kernel
// types like Point_2, so it's limited.

// The real solution will be to use "forwarding constructors", when they
// will be available in C++.
// In the mean time, this should be a mostly/hopefully internal hack.

CGAL_BEGIN_NAMESPACE

struct Return_base_tag {};

CGAL_END_NAMESPACE

#endif