/*=========================================================================

  Program:   CMake - Cross-Platform Makefile Generator
  Module:    $RCSfile$
  Language:  C++
  Date:      $Date$
  Version:   $Revision$

  Copyright (c) 2002 Kitware, Inc., Insight Consortium.  All rights reserved.
  See Copyright.txt or http://www.cmake.org/HTML/Copyright.html for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#ifndef cmUnsetCommand_h
#define cmUnsetCommand_h

#include "cmCommand.h"

/** \class cmUnsetCommand
 * \brief Unset a CMAKE variable
 *
 * cmUnsetCommand unsets or removes a variable.
 */
class cmUnsetCommand : public cmCommand
{
public:
  /**
   * This is a virtual constructor for the command.
   */
  virtual cmCommand* Clone()
    {
    return new cmUnsetCommand;
    }

  /**
   * This is called when the command is first encountered in
   * the CMakeLists.txt file.
   */
  virtual bool InitialPass(std::vector<std::string> const& args,
                           cmExecutionStatus &status);

  /**
   * This determines if the command is invoked when in script mode.
   */
  virtual bool IsScriptable() { return true; }

  /**
   * The name of the command as specified in CMakeList.txt.
   */
  virtual const char* GetName() {return "unset";}

  /**
   * Succinct documentation.
   */
  virtual const char* GetTerseDocumentation()
    {
    return "Unset a variable, cache variable, or environment variable.";
    }

  /**
   * More documentation.
   */
  virtual const char* GetFullDocumentation()
    {
    return
      "  unset(<variable> [CACHE])\n"
      "Removes the specified variable causing it to become undefined.  "
      "If CACHE is present then the variable is removed from the cache "
      "instead of the current scope.\n"
      "<variable> can be an environment variable such as:\n"
      "  unset(ENV{LD_LIBRARY_PATH})\n"
      "in which case the variable will be removed from the current "
      "environment.";
    }

  cmTypeMacro(cmUnsetCommand, cmCommand);
};



#endif
