Policy-Based Class Design

看到模板，自然的想要在实际中大量的使用之。于是寻求更好的方法，看到了《C++设计新思维》，第一章讲Policy-Based Class Design，深深的脑残了一回，查找了很多资料才算看懂……太佩服了，没想到C++可以这样用……

以下是我的练习代码。很神奇的。

 

/*===========================================================================*/ /*-------------------------------------- Policy-Based Class Design ------------------------------------------------------------*/ /*===========================================================================*/ template < class T > class BinaryReader { protected: void Read( ) { std::cout<<"read--use BinaryReader"<<std::endl; } }; template < class T > class BinaryWriter { protected: void Write( ) { std::cout<<"write--use BinaryWriter"<<std::endl; } }; template < class T > class XmlReader { protected: static void Read( ) { std::cout<<"read--use XmlReader"<<std::endl; } }; template < class T > class XmlWriter { protected: virtual void Write( ) { std::cout<<"write--use XmlWriter"<<std::endl; } }; template < class Subject, template< class > class ReadingPolicy, template< class > class WritingPolicy > class IOManager : public ReadingPolicy< Subject >, public WritingPolicy< Subject > { public: void Read( ) { ReadingPolicy< Subject >::Read(); } void Write( ) { WritingPolicy< Subject >::Write(); } };

 

客户端如下：

 

#include "test.h" #include <string> int main() { IOManager < std::string, BinaryReader, BinaryWriter > Manager1; Manager1.Read(); Manager1.Write(); IOManager < std::string, XmlReader, XmlWriter > Manager2; Manager2.Read(); Manager2.Write(); }

 

太神奇了。

从接触C++起，就被教导，要少用或不要多重继承，想不到多重继承在这里居然能有如此效果，实在想象不到。