Question

I created a module to add some Extension Methods to a Class.
This Class inherits from another parent Class.
In the code of my Extension Methods, I would like to refer to the base Class using MyBase.

This doesn’t seems to be allowed (Error message : “‘MyBase’ is not valid within a Module.“)

<Extension()>
Public Function Get_OutOfSpace(val as ClassA) As Boolean
    Return MyBase.IsOutOfSpace()
End Function

How can I invoke a method of my base class within an Extension Method?

Answer 1

That’s why they force you to write extension methods in a module, so you can’t make the mistake of using MyBase. But there’s at least one other thing wrong with your code, you didn’t extend anything. The first argument of an extension method must be a reference to the object, of the type you want to extend:

<Extension()>
Public Function Get_OutOfSpace(ByVal obj As Foo) As Boolean
    ''...
End Function

So a likely implementation is Return obj.IsOutOfSpace. Which in turn makes it very likely that you don’t actually have any use at all for this extension method since the class you want to extend already has an IsOutOfSpace property.

Only use extension methods to add methods to classes. And only do so if you can’t change the class.