Implementing 2 Interfaces with 'Same Name' Properties

Question

This seems like a reasonable (and maybe simple?) scenario, but how would you do the following:

Lets say I have 2 interfaces:

Interface ISimpleInterfa         


        

Answer 1

You can have private subroutines implement interfaces. It is only exposed when the object is assigned to a variable of that interface type.

Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim S As ISimpleInterface
        Dim Ext As IExtendedInterface
        Dim F As New Foo
        F.ErrorMsg = "Test Error"
        S = F
        Ext = F
        MsgBox(S.ErrorMsg)
        MsgBox(Ext.ErrorMsg)
        MsgBox(F.ErrorMsg)
    End Sub
End Class


Public Interface ISimpleInterface
    ReadOnly Property ErrorMsg() As String
End Interface

Public Interface IExtendedInterface
    Property ErrorMsg() As String
    Property SomeOtherProperty() As String
End Interface

Public Class Foo
    Implements ISimpleInterface, IExtendedInterface
    Private other As String
    Private msg As String

    Public Property ErrorMsg() As String Implements IExtendedInterface.ErrorMsg
        Get
            Return msg
        End Get
        Set(ByVal value As String)
            msg = value
        End Set
    End Property

    Public Property SomeOtherProperty() As String Implements IExtendedInterface.SomeOtherProperty
        Get
            Return other
        End Get
        Set(ByVal value As String)
            other = value
        End Set
    End Property

    Private ReadOnly Property ErrorMsgSimple() As String Implements ISimpleInterface.ErrorMsg
        Get
            Return ErrorMsg
        End Get
    End Property
End Class

Answer 2

In C#, an implicit implementation (with the set) can satisfy both of these:

class Foo : ISimpleInterface, IExtendedInterface
{
    public string ErrorMsg { get; set; } 
    public string SomeOtherProperty {get; set;}
}

If you want to change it, you can use explicit implementation ("Implements" in VB?) - in C#:

string ISimpleInterface.ErrorMsg
{
    get { return ErrorMsg; } // or something more interesting
}