在C ++中实现GetEnumerator
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03-07-2019 - |
题
在C#中我有以下类,它编译得很好:
<代码> class CustomItem { } 代码>
<代码>class CustomList : IList<CustomItem>
{
public CustomItem this[int index]
{
get { return null; }
set { throw new NotImplementedException(); }
}
public void CopyTo(CustomItem[] array, int arrayIndex)
{
}
public int Count { get { return 10; } }
public int IndexOf(CustomItem item) { throw new NotImplementedException(); }
public void Insert(int index, CustomItem item) { throw new NotImplementedException(); }
public void RemoveAt(int index) { throw new NotImplementedException(); }
public void Add(CustomItem item) { throw new NotImplementedException(); }
public void Clear() { throw new NotImplementedException(); }
public bool Contains(CustomItem item) { throw new NotImplementedException(); }
public bool IsReadOnly { get { return true; } }
public bool Remove(CustomItem item) { throw new NotImplementedException(); }
public IEnumerator<CustomItem> GetEnumerator() { throw new NotImplementedException(); }
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
{ throw new NotImplementedException(); }
}
代码> <代码> 代码>
当我在C ++中尝试相同时,我得到了几个编译器错误:
<代码> ref class CustomItemValue { }; 代码>
<代码>typedef CustomItemValue^ CustomItem;
ref class CustomList : public IList<CustomItem>
{
public:
property CustomItem default[int]
{
virtual CustomItem get(int index) { return nullptr; }
virtual void set(int index, CustomItem value) {}
}
virtual void CopyTo(array<CustomItem>^ array, int arrayIndex)
{
}
property int Count { virtual int get() { return 10; } }
virtual int IndexOf(CustomItem item) { throw gcnew NotImplementedException(); }
virtual void Insert(int index, CustomItem item) { throw gcnew NotImplementedException(); }
virtual void RemoveAt(int index) { throw gcnew NotImplementedException(); }
virtual void Add(CustomItem item) { throw gcnew NotImplementedException(); }
virtual void Clear() { throw new NotImplementedException(); }
virtual bool Contains(CustomItem item) { throw gcnew NotImplementedException(); }
property bool IsReadOnly { virtual bool get() { return true; } }
virtual bool Remove(CustomItem item) { throw gcnew NotImplementedException(); }
virtual IEnumerator<CustomItem>^ GetEnumerator() { throw gcnew NotImplementedException(); }
virtual System::Collections::IEnumerator^ GetEnumerator()
{ throw gcnew NotImplementedException(); }
};
代码> <代码> 代码>
编译器的错误消息是:
<代码> 。\ mc.cpp(38):错误C2556:'System :: Collections :: IEnumerator ^ CustomList :: GetEnumerator(void)':重载函数的区别仅在于'System :: Collections :: Generic :: IEnumerator ^的返回类型CustomList ::的GetEnumerator(无效)” 同 [ T = CustomItem的 ] 。\ mc.cpp(36):查看'CustomList :: GetEnumerator'的声明 。\ mc.cpp(38):错误C2371:'CustomList :: GetEnumerator':重定义;不同的基本类型 。\ mc.cpp(36):查看'CustomList :: GetEnumerator'的声明 代码>
任何人都可以帮我吗?
解决方案
您需要使用Microsoft特定的显式覆盖语法来覆盖两个GetEnumerator()方法:
virtual System::Collections::IEnumerator^ GetEnumerator2() = System::Collections::IEnumerable::GetEnumerator
{ throw gcnew NotImplementedException(); }
virtual IEnumerator<CustomItem>^ GetEnumerator()
{ throw gcnew NotImplementedException(); }
请注意,我将非泛型GetEnumerator方法重命名为GetEnumerator2,然后指定它覆盖System :: Collections :: IEnumerable :: GetEnumerator。您可以在此处中找到有关显式覆盖的更多信息
其他提示
你有错误信息的线索。你的GetEnumerator方法返回System :: Collections :: IEnumerator ^,而这个类还有另一个返回的方法 System :: Collections :: Generic :: IEnumerator ^,这个方法可能是从IList类继承的。
尝试使用System :: Collections :: Generic :: IEnumerator ^。
替换返回值