.NET: Interface Problem VB.net Getter Only Interface
- by snmcdonald
Why does an interface override a class definition and violate class encapsulation? I have included two samples below, one in C# and one in VB.net?
VB.net
Module Module1
Sub Main()
Dim testInterface As ITest = New TestMe
Console.WriteLine(testInterface.Testable) ''// Prints False
testInterface.Testable = True ''// Access to Private!!!
Console.WriteLine(testInterface.Testable) ''// Prints True
Dim testClass As TestMe = New TestMe
Console.WriteLine(testClass.Testable) ''// Prints False
''//testClass.Testable = True ''// Compile Error
Console.WriteLine(testClass.Testable) ''// Prints False
End Sub
End Module
Public Class TestMe : Implements ITest
Private m_testable As Boolean = False
Public Property Testable As Boolean Implements ITest.Testable
Get
Return m_testable
End Get
Private Set(ByVal value As Boolean)
m_testable = value
End Set
End Property
End Class
Interface ITest
Property Testable As Boolean
End Interface
C#
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace InterfaceCSTest
{
class Program
{
static void Main(string[] args)
{
ITest testInterface = new TestMe();
Console.WriteLine(testInterface.Testable);
testInterface.Testable = true;
Console.WriteLine(testInterface.Testable);
TestMe testClass = new TestMe();
Console.WriteLine(testClass.Testable);
//testClass.Testable = true;
Console.WriteLine(testClass.Testable);
}
}
class TestMe : ITest
{
private bool m_testable = false;
public bool Testable
{
get
{
return m_testable;
}
private set
{
m_testable = value;
}
}
}
interface ITest
{
bool Testable { get; set; }
}
}
More Specifically
How do I implement a interface in VB.net that will allow for a private setter. For example in C# I can declare:
class TestMe : ITest
{
private bool m_testable = false;
public bool Testable
{
get
{
return m_testable;
}
private set //No Compile Error here!
{
m_testable = value;
}
}
}
interface ITest
{
bool Testable { get; }
}
However, if I declare an interface property as readonly in VB.net I cannot create a setter. If I create a VB.net interface as just a plain old property then interface declarations will violate my encapsulation.
Public Class TestMe : Implements ITest
Private m_testable As Boolean = False
Public ReadOnly Property Testable As Boolean Implements ITest.Testable
Get
Return m_testable
End Get
Private Set(ByVal value As Boolean) ''//Compile Error
m_testable = value
End Set
End Property
End Class
Interface ITest
ReadOnly Property Testable As Boolean
End Interface
So my question is, how do I define a getter only Interface in VB.net with proper encapsulation?
I figured the first example would have been the best method. However, it appears as if interface definitions overrule class definitions. So I tried to create a getter only (Readonly) property like in C# but it does not work for VB.net. Maybe this is just a limitation of the language?
