Bug in ObservableCollection?

I seam to be having a little problem. Now, this may be me being stupid, but I can’t get an ObservableCollection to work if you pass it a generic type!

For example, consider the following code:

Public Class ItemBitCollection(Of TItem)
    Inherits ObservableCollection(Of ItemBit(Of TItem))


End Class

Public Class ItemBit(Of TItem)

    Private m_item As TItem

End Class

Now, if you create an instance of ItemBitCollection you will see an error on the IDE regardless of wither you use a custom object type or a String type to initialise it:

Why does this not work? What is ObservableCollection doing that maybe it should not? Time to get Reflector out…

After some looking at the source I am still none the wiser. Even if you dumb down your classes to the bare minimum you cant pass a generic type into an ObservableCollection.

This is a limitation if you ask me…

Annoying solution:

If you create a fixed class type:

Public Class ItemBitCollection(Of TItemBit)
    Inherits ObservableCollection(Of TItemBit)

End Class

Public MustInherit Class ItemBit(Of TItem)

    Private m_item As TItem

End Class

Public Class DefaultItemBit
    Inherits ItemBit(Of String)

End Class

 

And then pass that class in it does work:

Dim o As New ItemBitCollection(Of DefaultItemBit)

Although this is a work around, it causes other problems in my code… Ahh well… worth a try…