what is VB default property in C#?

Question

Found an example and I can't understand what it means.

How can I read from a DataRow or a DataReader using the same code?

I have no idea how to convert the interface and two classes in answer to C#?

Edit: Here is the code that I want to convert to C#:

Interface IIndexer
    Default ReadOnly Property Item(ByVal index As String)
End Interface

Class DataReaderWrapper
Implements IIndexer

Private ReadOnly _reader As IDataReader

Public Sub New(reader As IDataReader)
    _reader = reader
End Sub

Public ReadOnly Property Item(index As String) As Object Implements IIndexer.Item
    Get
        Return _reader(index)
    End Get
End Property
End Class

Class DataRowWrapper
Implements IIndexer

Private ReadOnly _row As DataRow

Public Sub New(row As DataRow)
    _row = row
End Sub

Public ReadOnly Property Item(index As String) As Object Implements IIndexer.Item
    Get
        Return _row(index)
    End Get
End Property
End Class

Matti what are you trying to convert.. why not paste the code here that of which you are trying to convert or want converted.. — MethodMan, Mar 10 '13 at 14:23
This should "answer" the problem with the `default` property: http://stackoverflow.com/questions/40730/how-do-you-give-a-c-sharp-auto-property-a-default-value — jAC, Mar 10 '13 at 14:24
@JanesAbouChleih - A default value on an auto-property is not the same as a default property of a type. — Oded, Mar 10 '13 at 14:26
Any reason you can't compile this code in a VB.NET project and reference it in C#? — Oded, Mar 10 '13 at 14:27
@Oded I used to code in VB6, then in VB.net for some years, Now I just can't stand it. — Federico Berasategui, Mar 10 '13 at 14:31
@HighCore - That's neither here nor there in regards to this question. You _can_ read and understand it, right? — Oded, Mar 10 '13 at 14:33
At 1st glance this VB-thing makes no sense whatsoever. How typing "End Property" can be better than "}" ? — char m, Mar 10 '13 at 14:34
@Oded yep, hes asking about `indexers` in C#, which are somewhat reminiscent of the default properties in VB.Net — Federico Berasategui, Mar 10 '13 at 14:35
FYI Joel and the gang and I will be discussing VB default properties and many other subjects in podcast #45. — Eric Lippert, Mar 10 '13 at 16:14

score 1 · Accepted Answer · answered Mar 10 '13 at 14:37

There is, as far as I know, no equivalent. More information about the Default keyword can be found at MSDN.

What you are seeing here is an Indexer in an Interface.

The converted code would be something like the following:

interface IIndexer
{
    object this[string index] { get; }
}

class DataReaderWrapper : IIndexer
{
    private readonly IDataReader _reader;
    public DataReaderWrapper(IDataReader reader)
    {
        _reader = reader;
    }

    public object this[string index]
    {
        get { return _reader[index]; }
    }
}

class DataRowWrapper : IIndexer
{
    private readonly DataRow _row;
    public DataRowWrapper(DataRow row)
    {
        _row = row;
    }

    public object this[string index]
    {
        get { return _row[index]; }
    }
}

Thanks a lot! This looks something I need. – char m Mar 10 '13 at 14:39 — char m, Mar 10 '13 at 14:39

score 0 · Answer 2 · answered Mar 10 '13 at 14:26

0

Something like this would work, it's unclear what you mean by 'default property':

var loadedItems = new List<Item>();
SqlDataReader dr = GetItemsDataReader();
while(dr.Read()){
  Item item = GetItemFromData(dr);
  loadedItems.Add(item);
}

private Item GetItemFromData(SqlDataReader dr){
  var loadedItem = new Item();
  loadedItem.ID = dr["ID"];
  loadedItem.Name = dr["Name"];
  'etc., etc.'
  Return loadedItem
}

answered Mar 10 '13 at 14:26

Echilon

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I mean: Default ReadOnly Property Item(ByVal index As String) – char m Mar 10 '13 at 14:27
@Oded: in examples I found in web they always have type like As Interger int the end but the interface's Item has not. – char m Mar 10 '13 at 14:32
1

I guess the C# equivalent would be `private Item this[int idx] { get { ... } }` – Echilon Mar 10 '13 at 14:32
thanks Echilon. I try to fit this information to the rest of the example. – char m Mar 10 '13 at 14:36

what is VB default property in C#?

2 Answers2