Select Case on an object's type in VB.NET

Question

I'm not sure if this valid C#, but hopefully you get the idea. :)

switch (msg.GetType()) {     case ClassA:         // blah     case ClassB:         // blah 2     case ClassC:         // blah 3 } 

How would I switch on an object's type but using VB.NET's Select Case?

I'm aware that some might suggest using polymorphism, but I'm using a hierarchy of small message classes so that really wouldn't work in my case.

Answer 1

With VB 2010, for projects targeting .NET framework 4 and later, you can now do this:

Select Case msg.GetType()     Case GetType(ClassA) End Select 

In earlier VB versions, it didn't work because you couldn't compare two types with equality. You'd have to check if they point to the same reference using the Is keyword. It's not possible to do this in a Select Case, unless you use a property of the type like the Name or FullName for comparison, as suggested by Michael. You can use a combination of If and ElseIf though:

Dim type = msg.GetType() If type Is GetType(ClassA)     ... ElseIf type Is GetType(ClassB)     ... ... End If 

Answer 2

Well, if you insist on using Select Case, you could always go with:

Select Case True     Case TypeOf msg Is ClassA         ' do something '     Case TypeOf msg Is ClassB         ' do something else '     Case Else         ' and so on ' End Select 

But I would imagine most people like to avoid this kind of thing. If/ElseIf would probably be clearer.