[mono-vb] Default Indexers

[Rolf Bjarne Kvinge]

Hi,

I implemented it by looping over all the interfaces manually, the fix has
been committed.

Thanks a lot!
Rolf

> -----Mensaje original-----
> De: mono-vb-bounces at lists.ximian.com [mailto:mono-vb-
> bounces at lists.ximian.com] En nombre de John Lenz
> Enviado el: jueves, 08 de abril de 2010 20:32
> Para: mono-vb at lists.ximian.com
> Asunto: [mono-vb] Default Indexers
> 
> Hi,
> 
> The following code gives me VBNC30471 while MS.NET compiles it fine.
> 
> Imports System.Data
> 
> Public Class Main
> 
>    Public Shared Sub Main()
>        Dim reader As IDataReader
>        Dim a As Object
> 
>        a = reader(0)
>    End Sub
> 
> End Class
> 
> 
> I traced the problem down to Helper.vb line 1560:
> 
> System.Attribute.GetCustomAttribute(Type,
> GetType(DefaultMemberAttribute), True)
> 
> When Type is System.Data.IDataReader this call returns Nothing.  The
> issue is that the default
> indexer is actually declared on IDataRecord, see
> 
> http://anonsvn.mono-
> project.com/viewvc/trunk/mcs/class/System.Data/System.Data/IDataReader.
> cs
> 
> http://anonsvn.mono-
> project.com/viewvc/trunk/mcs/class/System.Data/System.Data/IDataRecord.
> cs
> 
> The problem is that if you look at the code for GetCustomAttribute it
> does not check base classes
> for the DefaultMemberAttribute even though you pass True.  (The inherit
> flag is reset to false in
> MonoCustomAttrs.cs::GetCustomAttributes() because the attribute does
> not have the
> AttributeUsage.Inherited flag).  Therefore when searching for the
> DefaultMemberAttribute on
> IDataReader nothing is found.
> 
> I looked at what gmcs does and the closest thing I could find is in
> expression.cs line 8411
> 
> http://anonsvn.mono-
> project.com/viewvc/trunk/mcs/mcs/expression.cs?revision=152858#l8411
> 
> http://anonsvn.mono-
> project.com/viewvc/trunk/mcs/mcs/typemanager.cs?revision=152808#l2354
> 
> Looking at the IndexerPropertyName() function in typemanager.cs, it
> seems like gmcs just uses a name
> of "Item" if it can't find anything.  I am not sure if that is the
> correct behavior for VB.
> Perhaps we should just manually check base classes for
> DefaultMemberAttribute since
> GetCustomAttribute does not do it.  Something like
> 
> Dim defAttr  As Type = GetType(DefaultMemberAttribute)
> attr = Attribute.GetCustomAttribute(Type, defAttr)
> 
> If attr Is Nothing Then
> 
>    For Each t As Type in Type.GetInterfaces()
>       attr = Attribute.GetCustomAttribute(t, defAttr)
>       If attr IsNot Nothing Then Exit For
>    Next
> 
> End If
> 
> What do you think?
> 
> John
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