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

While explicit implementation will solve this, as shown by others, in this very case i would probably let IExtendedInterface implement ISimpleInterface (ErrorMsg property is semantically the same property, it means the same in these 2 interfaces i would guess).

interface ISimpleInterface
{
    string ErrorMessage { get; set; }
}
interface IExtendedInterface : ISimpleInterface
{
    string SomeOtherProperty { get; set; }
}

Answer 2

In C# you can use explicit interface implementation:

class Foo
{
    string ISimpleInterface.ErrorMsg
    { get... }

    string IExtendedInterface.ErrorMsg
    { get... set... }

    string IExtendedInterface.SomeOtherProperty
    { get... set... }
}

or Interface Mapping

class Foo
{
    public string ErrorMsg
    { get... set... }       

    public string SomeOtherProperty
    { get... set... }
}

As for VB.NET, it has Implements keyword:

Property ErrorMsg As String Implements ISimpleInterface.ErrorMsg

Property OtherErrorMsg As String Implements IExtendedInterface.ErrorMsg

Answer 3

The Implements keyword in VB.NET makes this easy:

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

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

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

  Public ReadOnly Property ErrorMsg() As String Implements ISimpleInterface.ErrorMsg
    Get
      Return msg
    End Get
  End Property
End Class

Answer 4

You can implement one of them or both interfaces with an 'explicit interface' implementation, so the compiler knows which ErrorMsg property belongs to which interface.

To do this simply write :ISimpleInterface (for C#) after your class name and then click on ISimpleInterface and select implement explicit interface.

More information here: http://msdn.microsoft.com/en-us/library/aa288461(VS.71).aspx

Answer 5

You will need to work with Explicit Interface Implementations. More on the subject here: http://msdn.microsoft.com/en-us/library/aa288461(VS.71).aspx

Answer 6

Sorry but I don't master VB.Net syntax.

In C# you can implement interfaces implicitly or explicitly. If your class Foo implements ErrorMsg as a public method, this implementation will be used for both interface.

If you want distinct implementation you can implement it explicitly :

string ISimpleInterface.ErrorMsg {get { ... } } 
string IExtendedInterface.ErrorMsg {get { ... } set { ... }}