ACE自适配通信环境（ADAPTIVE Communication Environment）是可以自由使用、开放源码的面向对象（OO）框架（Framework）

				// file      : Utility/Synch/Policy/Null.hpp				// author    : Boris Kolpackov 				// copyright : Copyright (c) 2002-2003 Boris Kolpackov				// license   : http://kolpackov.net/license.html								#ifndef UTILITY_SYNCH_POLICY_NULL_HPP				#define UTILITY_SYNCH_POLICY_NULL_HPP								namespace Utility				{				  namespace Synch				  {				    namespace Policy				    {								      class NullMutex				      {				      };								      class NullGuard				      {				      public:				        explicit				        NullGuard (NullMutex&) throw ();								      private:				        NullGuard (NullGuard const&) throw ();								        NullGuard&				        operator= (NullGuard const&) throw ();				      };								      struct Null				      {				        typedef				        NullMutex				        Mutex;								        typedef				        NullGuard				        ReadGuard;								        typedef				        NullGuard				        WriteGuard;				      };				    }				  }				}								#include "Utility/Synch/Policy/Null.ipp"								#endif  // UTILITY_SYNCH_POLICY_NULL_HPP				//Null.hpp,v 1.1 2005/05/24 04:33:13 turkaye Exp