在 VB.NET 中创建可从 C# 使用的索引器

发布于 2024-11-06 20:28:46 字数 717 浏览 0 评论 0原文

我可以在 VB.NET 中创建一个可以在 C# 中使用的类吗：

myObject.Objects[index].Prop = 1234;

当然，我可以创建一个返回数组的属性。但要求是索引是从 1 开始的，而不是从 0 开始的，所以这个方法必须以某种方式映射索引：

我试图这样做，但 C# 告诉我不能直接调用它：

   Public ReadOnly Property Objects(ByVal index As Integer) As ObjectData
        Get
            If (index = 0) Then
                Throw New ArgumentOutOfRangeException()
            End If
            Return parrObjectData(index)
        End Get
    End Property

编辑抱歉，如果我有点不清楚：

C# 只允许我调用此方法，如

myObject.get_Objects(index).Prop = 1234

但不允许

myObject.Objects[index].Prop = 1234;

这就是我想要实现的目标。

原文

Can I create a class in VB.NET which can be used from C# like that:

myObject.Objects[index].Prop = 1234;

Sure I could create a property which returns an array. But the requirement is that the index is 1-based, not 0-based, so this method has to map the indices somehow:

I was trying to make it like that, but C# told me I cannot call this directly:

   Public ReadOnly Property Objects(ByVal index As Integer) As ObjectData
        Get
            If (index = 0) Then
                Throw New ArgumentOutOfRangeException()
            End If
            Return parrObjectData(index)
        End Get
    End Property

EDIT
Sorry if I was a bit unclear:

C# only allows my to call this method like

myObject.get_Objects(index).Prop = 1234

but not

myObject.Objects[index].Prop = 1234;

this is what I want to achieve.

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半暖夏伤 2024-11-13 20:28:46

语法是：

Default Public ReadOnly Property Item(ByVal index as Integer) As ObjectData
  Get
    If (index = 0) Then
      Throw New ArgumentOutOfRangeException()
    End If
    Return parrObjectData(index)
  End Get
End Property

Default 关键字是创建索引器的魔法。不幸的是，C# 不支持命名索引器。您将必须创建一个自定义集合包装器并返回它。

Public ReadOnly Property Objects As ICollection(Of ObjectData)
  Get
    Return New CollectionWrapper(parrObjectData)
  End Get
End Property

其中 CollectionWrapper 可能如下所示：

Private Class CollectionWrapper
  Implements ICollection(Of ObjectData)

  Private m_Collection As ICollection(Of ObjectData)

  Public Sub New(ByVal collection As ICollection(Of ObjectData))
    m_Collection = collection
  End Sub

  Default Public ReadOnly Property Item(ByVal index as Integer) As ObjectData
    Get
      If (index = 0) Then
        Throw New ArgumentOutOfRangeException()
      End If
      Return m_Collection(index)
    End Get
  End Property

End Class

The syntax is:

Default Public ReadOnly Property Item(ByVal index as Integer) As ObjectData
  Get
    If (index = 0) Then
      Throw New ArgumentOutOfRangeException()
    End If
    Return parrObjectData(index)
  End Get
End Property

The Default keyword is the magic that creates the indexer. Unfortunately C# does not support named indexers. You are going to have to create a custom collection wrapper and return that instead.

Public ReadOnly Property Objects As ICollection(Of ObjectData)
  Get
    Return New CollectionWrapper(parrObjectData)
  End Get
End Property

Where the CollectionWrapper might would look like this:

Private Class CollectionWrapper
  Implements ICollection(Of ObjectData)

  Private m_Collection As ICollection(Of ObjectData)

  Public Sub New(ByVal collection As ICollection(Of ObjectData))
    m_Collection = collection
  End Sub

  Default Public ReadOnly Property Item(ByVal index as Integer) As ObjectData
    Get
      If (index = 0) Then
        Throw New ArgumentOutOfRangeException()
      End If
      Return m_Collection(index)
    End Get
  End Property

End Class

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红墙和绿瓦 2024-11-13 20:28:46

您可以使用带有默认索引器的结构在 C# 中伪造命名索引器：

public class ObjectData
{
}

public class MyClass
{
    private List<ObjectData> _objects=new List<ObjectData>();
    public ObjectsIndexer Objects{get{return new ObjectsIndexer(this);}}

    public struct ObjectsIndexer
    {
        private MyClass _instance;

        internal ObjectsIndexer(MyClass instance)
        {
            _instance=instance;
        }

        public ObjectData this[int index]
        {
            get
            {
                return _instance._objects[index-1];
            }
        }
    }
}

void Main()
{
        MyClass cls=new MyClass();
        ObjectData data=cls.Objects[1];
}

如果这是一个好主意，那就是另一个问题了。

You can fake named indexers in C# using a struct with a default indexer:

public class ObjectData
{
}

public class MyClass
{
    private List<ObjectData> _objects=new List<ObjectData>();
    public ObjectsIndexer Objects{get{return new ObjectsIndexer(this);}}

    public struct ObjectsIndexer
    {
        private MyClass _instance;

        internal ObjectsIndexer(MyClass instance)
        {
            _instance=instance;
        }

        public ObjectData this[int index]
        {
            get
            {
                return _instance._objects[index-1];
            }
        }
    }
}

void Main()
{
        MyClass cls=new MyClass();
        ObjectData data=cls.Objects[1];
}

If that's a good idea is a different question.

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