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diff --git a/Source/cmVariableWatchCommand.h b/Source/cmVariableWatchCommand.h
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+++ b/Source/cmVariableWatchCommand.h
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+/*============================================================================
+  CMake - Cross Platform Makefile Generator
+  Copyright 2000-2009 Kitware, Inc., Insight Software Consortium
+
+  Distributed under the OSI-approved BSD License (the "License");
+  see accompanying file Copyright.txt for details.
+
+  This software is distributed WITHOUT ANY WARRANTY; without even the
+  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the License for more information.
+============================================================================*/
+#ifndef cmVariableWatchCommand_h
+#define cmVariableWatchCommand_h
+
+#include "cmCommand.h"
+
+class cmVariableWatchCommandHandler
+{
+public:
+  typedef std::vector<std::string> VectorOfCommands;
+  VectorOfCommands Commands;
+};
+
+/** \class cmVariableWatchCommand
+ * \brief Watch when the variable changes and invoke command
+ *
+ */
+class cmVariableWatchCommand : public cmCommand
+{
+public:
+  /**
+   * This is a virtual constructor for the command.
+   */
+  virtual cmCommand* Clone() 
+    {
+    return new cmVariableWatchCommand;
+    }
+
+  //! Default constructor
+  cmVariableWatchCommand();
+
+  /**
+   * 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() const { return true; }
+
+  /** This command does not really have a final pass but it needs to
+      stay alive since it owns variable watch callback information. */
+  virtual bool HasFinalPass() const { return true; }
+
+  /**
+   * The name of the command as specified in CMakeList.txt.
+   */
+  virtual const char* GetName() const { return "variable_watch";}
+
+  /**
+   * Succinct documentation.
+   */
+  virtual const char* GetTerseDocumentation() const
+    {
+    return "Watch the CMake variable for change.";
+    }
+  
+  /**
+   * More documentation.
+   */
+  virtual const char* GetFullDocumentation() const
+    {
+    return
+      "  variable_watch(<variable name> [<command to execute>])\n"
+      "If the specified variable changes, the message will be printed about "
+      "the variable being changed. If the command is specified, the command "
+      "will be executed. The command will receive the following arguments:"
+      " COMMAND(<variable> <access> <value> <current list file> <stack>)";
+    }
+  
+  cmTypeMacro(cmVariableWatchCommand, cmCommand);
+
+  void VariableAccessed(const std::string& variable, int access_type,
+    const char* newValue, const cmMakefile* mf);
+
+protected:
+  std::map<std::string, cmVariableWatchCommandHandler> Handlers;
+
+  bool InCallback;
+};
+
+
+#endif
+
+