关于Policy Based Class Design--《Modern C++ Design》读后感一
2006-12-26 19:11
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前不久阅读了一下 Andrei Alexandrescu的大作《Modern C++ Design》,深受启发。现写一些读后感,一个是促进自己学习,二者是希望大家交流,抛砖引玉。
说到底Policy Based Class Design是基于Templete模版的Templete组件设计技术,就是用内Templete来作为Policy为外Templete提供可配置的服务。
例如:
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
template<class T,Template<class> class Policy1,Template<class>class Policy2 >
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
class PolicyBasedClass:public Policy1<T>,public Policy2<T>
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/a41954a27d6ad96fa2c2cf816e677448.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/1327ab569c1ae82736693a50b8e33378.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/0196c3df5ea9e936f21e9932cca91014.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
当然Policy1也可以不依赖于模版T。同样Policy2也可以。这样也当然也可以。
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
template<class T,class Policy1,class Policy2 >
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
class PolicyBasedClass:public Policy1,public Policy2
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/a41954a27d6ad96fa2c2cf816e677448.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/1327ab569c1ae82736693a50b8e33378.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/0196c3df5ea9e936f21e9932cca91014.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
当然第一个例子更加具有通用性。
这样你可以代入不同的Policy Class,来改变PolicyBasedClass的行为。
而所有的配置都是在编译阶段完成的,而不是RunTime,所以没有任何的性能损失。
有人说,我可以加个参数,对这个Class做重载,当然是可以的,而且可以获得运行时刻的灵活性,当然系统的开销相对也会大一些。
所以个人认为,PolicyBasedClass更加适合于做一些Framework的工作。例如设计一个基础的框架库,这个技术就很实用。所以Loki也是这样子的一个库。
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
namespace SHFTest
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/a41954a27d6ad96fa2c2cf816e677448.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/1327ab569c1ae82736693a50b8e33378.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
template <class T>
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
struct OpNewCreator
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
static T* Create()
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
return new T;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
protected:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
~OpNewCreator()...{};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
template <class T>
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
struct MallocCreator
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
static T* Create()
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](http://images.csdn.net/s<br/>10251<br/>yntaxhighlighting/OutliningIndicators/ContractedSubBlock.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
T* buf = (T*)std::malloc(sizeof(T));
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
if ( !buf )
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
return 0;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
return buf;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
protected:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
~MallocCreator()...{};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
template <class T>
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
struct ProtypeCreator
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
public:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
T* Create()
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
return /**//*pPrototype_ ? pPrototype_->Clone() :*/ 0;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
T* GetPrototype() ...{ return pPrototype_; }
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
void SetPrototype(T* pObj) ...{ pPrototype_ = pObj; }
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
protected:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
~ProtypeCreator()...{};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
private:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
T* pPrototype_;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
template<
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
class T,
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
template <class> class CreatePolicy = OpNewCreator
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
>
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
class CommonObj:public CreatePolicy<T>
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
public:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
CommonObj()
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
CreatePolicy<T>::Create();
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
~CommonObj()...{}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
void Test()
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
std::cout<<"Hello World";
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
protected:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/0196c3df5ea9e936f21e9932cca91014.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
int _tmain(int argc, _TCHAR* argv[])
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/a41954a27d6ad96fa2c2cf816e677448.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/1327ab569c1ae82736693a50b8e33378.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
typedef SHFTest::CommonObj<int,SHFTest::ProtypeCreator> myProtypeObj;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
myProtypeObj Testobj1;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
Testobj1.Test();
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
typedef SHFTest::CommonObj<int> myObj;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
myObj Testobj2;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
Testobj2.Test();
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
return 0;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/0196c3df5ea9e936f21e9932cca91014.gif)
}
以上是个人读后感的,有什么不对的地方希望大家指正。
说到底Policy Based Class Design是基于Templete模版的Templete组件设计技术,就是用内Templete来作为Policy为外Templete提供可配置的服务。
例如:
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
template<class T,Template<class> class Policy1,Template<class>class Policy2 >
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
class PolicyBasedClass:public Policy1<T>,public Policy2<T>
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/a41954a27d6ad96fa2c2cf816e677448.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/1327ab569c1ae82736693a50b8e33378.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/0196c3df5ea9e936f21e9932cca91014.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
当然Policy1也可以不依赖于模版T。同样Policy2也可以。这样也当然也可以。
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
template<class T,class Policy1,class Policy2 >
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
class PolicyBasedClass:public Policy1,public Policy2
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/a41954a27d6ad96fa2c2cf816e677448.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/1327ab569c1ae82736693a50b8e33378.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/0196c3df5ea9e936f21e9932cca91014.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
当然第一个例子更加具有通用性。
这样你可以代入不同的Policy Class,来改变PolicyBasedClass的行为。
而所有的配置都是在编译阶段完成的,而不是RunTime,所以没有任何的性能损失。
有人说,我可以加个参数,对这个Class做重载,当然是可以的,而且可以获得运行时刻的灵活性,当然系统的开销相对也会大一些。
所以个人认为,PolicyBasedClass更加适合于做一些Framework的工作。例如设计一个基础的框架库,这个技术就很实用。所以Loki也是这样子的一个库。
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
namespace SHFTest
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/a41954a27d6ad96fa2c2cf816e677448.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/1327ab569c1ae82736693a50b8e33378.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
template <class T>
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
struct OpNewCreator
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
static T* Create()
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
return new T;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
protected:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
~OpNewCreator()...{};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
template <class T>
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
struct MallocCreator
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
static T* Create()
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](http://images.csdn.net/s<br/>10251<br/>yntaxhighlighting/OutliningIndicators/ContractedSubBlock.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
T* buf = (T*)std::malloc(sizeof(T));
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
if ( !buf )
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
return 0;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
return buf;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
protected:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
~MallocCreator()...{};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
template <class T>
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
struct ProtypeCreator
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
public:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
T* Create()
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
return /**//*pPrototype_ ? pPrototype_->Clone() :*/ 0;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
T* GetPrototype() ...{ return pPrototype_; }
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
void SetPrototype(T* pObj) ...{ pPrototype_ = pObj; }
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
protected:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
~ProtypeCreator()...{};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
private:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
T* pPrototype_;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
template<
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
class T,
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
template <class> class CreatePolicy = OpNewCreator
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
>
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
class CommonObj:public CreatePolicy<T>
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
public:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
CommonObj()
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
CreatePolicy<T>::Create();
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
~CommonObj()...{}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
void Test()
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/37c8bf68cdc3cc81759c34160776bc53.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/7ff8d92cded7e0ce15e7ca1acc870052.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
std::cout<<"Hello World";
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
protected:
![](https://oscdn.geek-share.com/Uploads/Images/Content/201104/717446ca04a6125dc5b6b54e0fa14ab4.gif)
};
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/0196c3df5ea9e936f21e9932cca91014.gif)
}
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/2015/2015030196/6810355c2f78c12e91b7997a8e8c583a.gif)
int _tmain(int argc, _TCHAR* argv[])
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/a41954a27d6ad96fa2c2cf816e677448.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/1327ab569c1ae82736693a50b8e33378.gif)
...{
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
typedef SHFTest::CommonObj<int,SHFTest::ProtypeCreator> myProtypeObj;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
myProtypeObj Testobj1;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
Testobj1.Test();
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
typedef SHFTest::CommonObj<int> myObj;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
myObj Testobj2;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
Testobj2.Test();
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/6a9c071a08f1dae2d3e1c512000eef41.gif)
return 0;
![](https://oscdn.geek-share.com/Uploads/Images/Content/201109/0196c3df5ea9e936f21e9932cca91014.gif)
}
以上是个人读后感的,有什么不对的地方希望大家指正。
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