泛化Factory-优快云博客

本文链接：https://blog.youkuaiyun.com/shenya1314/article/details/54646120

本文介绍了一个图形绘制类和使用工厂模式创建不同类型的图形对象的方法。通过定义抽象基类Shape及其实现Draw、Rotate和Zoom等操作，展示了如何在运行时根据类型创建具体的图形对象并进行保存与加载。

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class Shape
{
public :
virtual void Draw()const=0;
virtual void Rotate(double angle) =0;
virtual void Zoom(double zoomFactor)=0;
}
class Drawing
{
public:
void Save(std::ofstream OutFile);
void Load(std::ifstream inFile);
}
void Drawing::Save(std::ofstream& outFile)
{
for(each element in the drawing)
{
  (current element()->Save(outFile));
}
}
根据DrawingType产生对象
namespace DrawingType
{
const int
Line =1,
POLYGON=2,
CIRCLE=3
};
void Drawing::Load(std::ifstream& inFile)
{
while(inFile)
{
  int drawingType;
  inFile>>drawingType;
  Shape* pCurrentObject;
  switch(drawingType)
  using namespace DrawingType;
  case LINE:
   pCurrentObject=new Line;
   break;
  case: POLYGON
   pCurrentObjecct=new Polygon;
   break;
}
}

map存储对象
class ShapeFactory
{
public :
typedef Shape* (*CreateShapeCallback)();
private:
tyepdef std::map<int ,CreateShapeCallback>CallbackMap;
public:
bool RegisterShape(int ShapeId,CreateShapeCallback CreateFn);
bool UnregisterShape(int ShapeId);
Shape*CreateShape(int ShapeId);
private:
CallbackMap callbacks_;
}

泛化工程模式
template <
class AbstractProduct,
typename IdentifierType
typename ProductCreator
tempalte<typename ,class> class FactoryErrorPolicy
>
class Factor
{
public:
bool Register(const IdentifierType&id,ProductCreator creator)
{
  return asociation_.insert(AssocMap::value_type(id,creator)).second;
}
bool Unregister(const IdentifierType& id)
{
  return associations_.erase(id)==1;
}
AbstractProduct* CreateObject(const IdentifierType &od)
{
  typename AssocMap::const_iterator i= association_.find(id);
  if(i !=associations_.end())
  {
   return (i->second)();
  }
  return OnUnknownType(id);
}
private:
typedef std::map<IdentifierType,AbstractProduct> AssocMap;
AssocMap associations_;
};
template<class IndentifierType,class ProcductType>
class DefaultFactorError
{
pubclic Execption:publcid std::exception
{
  public :
  Exception(const IdentifierType& unknowId):unknownId_(unknownId)
  {

  }
  virtual const char * what()
  {
   return "Unknow";
  }
  const IdentifierType GetId()
  {
   return unknowId_;
  }
  private:
  IdentifierType unknownId_;
}
protected:
StaticProductType* OnUnknownType(const IdentifierType&id)
{
  throw Exception(id);
}
}