MyBase (base) Object Property not showing actual value in the debugger

Question

So I get a paniced IM from a coworker saying this if statement is skipping when

If true Then
    DoSomething
End IF

The actual code being

If MyBase.IsDirty Then
    DoSomething
End IF

C# Version

if(base.IsDirty)
{
    DoSomething();
}

My first question to them was well the If statement isn't magically broken so are you sure MyBase.IsDirty is actually true? They responded 'Yes OF COURSE!'. Upon asking them how they determined this they said they were putting a breakpoint at the line and hovering over MyBase.IsDirty to see what the value was and that they had also done ?MyBase.IsDirty in the immediate window. My initial thought and what I am thinking to still be correct is due to the way that base classes function that it wasn't actually showing the value at in those cases (at least the correct one) so I suggested doing

Dim dirty As Boolean = MyBase.IsDirty

Then running the code again, which showed as I guessed that dirty was actually false.

Now why is this the case? As far as I can tell it has something to do with the way that MyBase is implemented but I want specifics so I can have a 100% answer to this.

Edit

Right so MyBase.IsDirty is a Boolean

The Get is done as Follows:

<Browsable(False)> _
    Public Overridable ReadOnly Property IsDirty() As Boolean Implements IEditableBusinessObject.IsDirty
      Get
        Return IsSelfDirty OrElse (_fieldManager IsNot Nothing AndAlso FieldManager.IsDirty())
      End Get
    End Property

Where

<Browsable(False)> _
    Public Overridable ReadOnly Property IsSelfDirty() As Boolean Implements IEditableBusinessObject.IsSelfDirty
      Get
        Return _isDirty
      End Get
    End Property

And

_isDirty is Initialized as true

(Field Manager is a non issue for this case).

I should note that this is all taken from CSLA 3.5.3.0

Another Edit

I'm calling MyBase.IsDirty because that is the way that Rocky Lhotka shows it being done in his books on CSLA.

Answer 1

The debugger can't evaluate expressions using the base (or MyBase in VB) keyword correctly because the debugging API doesn't support non virtual calls. It returns the value a virtual call to the getter returns instead of the one the getter in the base class returns. So the effect you're observing is a debugger problem.

I guess you overrode the property in the derived class and return false there, and that's what the debugger shows. The compiled code itself will handle the base. call correctly.

The MSDN blog entry "Debugger won't properly evaluate C#s base keyword" describes this problem in detail