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:

 1Public Class ItemBitCollection(Of TItem)
 2    Inherits ObservableCollection(Of ItemBit(Of TItem))
 3
 4
 5End Class
 6
 7Public Class ItemBit(Of TItem)
 8
 9    Private m_item As TItem
10
11End 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:

 1Public Class ItemBitCollection(Of TItemBit)
 2    Inherits ObservableCollection(Of TItemBit)
 3
 4End Class
 5
 6Public MustInherit Class ItemBit(Of TItem)
 7
 8    Private m_item As TItem
 9
10End Class
11
12Public Class DefaultItemBit
13    Inherits ItemBit(Of String)
14
15End Class

And then pass that class in it does work:

1Dim o As New ItemBitCollection(Of DefaultItemBit)

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

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