自动生成代码

loki 提供一个极具威力的工具，可轻易将typelist里的每一个型别套用于一个由用户提供的基本template身上

这么一来将typelist 内的型别分发至客端代码的一些不便过程就被完全封装在loki程序库中，使用者只需自行定义一个单一template

template <class TList,template <class>class Unit>

class GenScatterHierarchy;

template <class T1,class T2,template <class >class Unit>

class GenScatterHierarchy<TYPELIST_2(T1,T2),Unit>;public GenScatterHierarchy<T1,Unit>,public GenScatterHierarchy<T2,Unit>

{

 

};

template  <class AtomicType,template <class>class Unit>

class GenScatterHierarchy:public Unit<ActomicType>

{

 

};

template <template<class>class Unit>

class GenScatterHierarchy<NullType,Unit>

{

 

};

最终一一具现体

template <class T>

struct Holder

{

 T value_;

}

typedef GenScatterHierarchy<TYPELIST_3(int,string,Widget),Holder>WidgetInfo;

根据型别取成员变量

template <class T,class TList,template <class>class Unit>

Unit <T>&Field (GenScatterHierarchy<TList,Unit>&obj)

{

 return obj;

}，

自动继承，注意符号相同会隐藏，typelist中不能有重复型别时

解决方式

我们需要一个“以索引选择GenSCatterHierarchy”实体栏位的方法,引导继承的方式

template <class TList,tempate<class>class Unit>

Unit<TList::Head>& FieldHelper(

GenSatterHierarchy<TList,Unit>&obj,Int2Type<0>)

{

 GenScatterHierarchy<TList::Head,Unit>& leftBase= obj;

 return  leftBase;

}

template <int i ,class TList,template<class>class Unit>

Unit<TypeAt<TList,index>::Result>&

FieldHelper(

 GenScatterHierarchy<TList,Unit>& obj,

 Int2Type<i>)

{

 GenScatterHierarchy<TList::Tail,Unit>& rightBase=obj;

 return FieldHelper(rightBase,Int2Type<i-1>());

}

template <int i ,class TList,Template <class>class Unit>

Unit <TypeAt<TList,index>::Result>&

Field(GenScatterHierarchy<TList,Unit>&obj)

{

 return FieldHeler(obj,Int2Type<i>());

}

如此可以通过索引

WidgetInfo obj;

int x= Field<0>(obj).value_;

int y= Field<1>(obj).value_;

tuples

template <class T>

struct Holder

{

 T value_

}

typedef GenScatterHierarchy<

 TYPELIST_3(int,int,int),Holder>

 Point3D;

Loki定义的Tuple temPplate class 可以直接访问&value,不需要从对象间接访问value

example

typedef Tuple<TYPELIST_3(int,int,int)>  Point3D;

Point3D pt;

Field<0>(pt)=0;

Field<1>(pt)=100;

Field<2>(pt)=300;

获取值

Tuple<TYPELIST_3(int,int,int)>

GetWindowPlacement(Window&);

单线继承方式

template

<

 calss TList;

 template <class AtmoicType,class Base>class Uint,class Root= EmptyType

>

class GenLinearHierarchy;

template

<

class T1,

class T2,

template<class ,class>class Unit,

class Root

>

class GenLinearHierarchy<Typelist<T1,T2>,Unit,Root>

:public Unit<T1,GenLinearHierarchy<T2,Unit,Root>>

{

 

};

template

<

class T,

template<class ,class>class Unit,

class Root

>

class GenLinearHierarchy<TYPELIST_1(T),Unit,Root>

:public Unit<T,Root>

{

 

};

template<class T,class Base>

class EventHandle:public Base

{

 public:

 virtual void onEvent(T &obj,int eventId);

}

typedef GenLinearHierarchy

<

TYPELIST_3(Window,Button,ScrollBar),

EventHandler

>

MyEventHanldr;

Over!