silverlight/c++开发笔记（继承与模板）

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1关键 public IXRCollection<IXRDependencyObject*, IXRDependencyObject*>

和template <typename In_T, typename Out_T>对应。

父类：

template <typename In_T, typename Out_T>
class __declspec(novtable) IXRCollection :
   public IXRDependencyObject
{
public:
   /// <summary>
   /// Add an item to the collection and optionaly get back the index where it was added.
   /// </summary>
   /// <param name="pvalue">[in] value to be added</param>
   /// <param name="pIndex">[out, optional] index where this item was added</param>
   virtual HRESULT STDMETHODCALLTYPE Add(
   In_T pvalue,
   __out_opt int *pIndex
   ) = 0;

。。。。。。

}；

子类：

class __declspec(novtable) IXRItemCollection : public IXRCollection<IXRDependencyObject*, IXRDependencyObject*>
{
public:
};

实例化子类：

IXRItemCollection* ppItems;

hr = ppItems->Add((IXRDependencyObject*)pComBoxItem,NULL);

2silverlight中比较上层的类，很多类都可以调用这些方法：

class __declspec(novtable) IXRDependencyObject:
public IUnknown
{
public:

virtual HRESULT STDMETHODCALLTYPE SetName(__in const WCHAR* pName) = 0;
virtual HRESULT STDMETHODCALLTYPE GetName(__out BSTR* pName) = 0;

......

virtual HRESULT STDMETHODCALLTYPE GetAttachedProperty(const WCHAR *pDP, XRGridLength *pValue) = 0;

......

};

3多态的实际运用：

HRESULT CShell::OnClickDial_MicSwitch( IXRDependencyObject * pSender , XRMouseButtonEventArgs * pArgs)

{

HRESULT hr = ((IXRButtonPtr)pSender)->SetVisibility(XRVisibility_Collapsed);

}

点击的时候系统调用OnClickDial_MicSwitch函数并且给IXRDependencyObject 赋IXRButtonPtr类型的值。强制转换还原。