CODEWITHSUNDEEP
vb.netgenericstypes
Terry
Terry

Reputation: 5262

Difficulties sending a type to a generic list

I'm trying to use a generic list without knowing the type when loading the page. I have a typePropertyCollection which inherits from List(Of PropertyData). The usercontrol that uses this collection doesn't know what type of data is used (which objects). So when the page is loaded, I pass along the type to the usercontrol using a dependencyproperty. This type ends up in this method:

Private Shared Sub OnObjectTypeChanged(ByVal obj As DependencyObject, ByVal args As DependencyPropertyChangedEventArgs)
    Dim objectType As Type = TryCast(args.NewValue, Type)
    Dim aList As List(Of PropertyData) = New TypePropertyCollection(Of objectType)
End Sub

I can succesfully retrieve the type from the EventArgs and put it in a variable. When I'm creating a new typePropertyCollection, I want to pass the type to the generic list, but it says the objectType isn't defined, although is is declared just the line above.

Any suggestions?

Edit

The class typepropertyCollection looks like this:

Public Sub New()
    Dim properties = New List(Of PropertyInfo)(GetType(T).GetProperties(BindingFlags.Public Or BindingFlags.Instance))
    For Each propertyToCheck In properties
        Dim descriptionAttribute = propertyToCheck.GetCustomAttributes(GetType(DescriptionAttribute), True)
        If Not descriptionAttribute Is Nothing AndAlso descriptionAttribute.Length > 0 Then
            Add(New PropertyData() With {.Description = DirectCast(descriptionAttribute(0), DescriptionAttribute).Description, .PropertyName = propertyToCheck.Name})
        Else
            Add(New PropertyData() With {.Description = propertyToCheck.Name, .PropertyName = propertyToCheck.Name})
        End If
    Next
End Sub

To use this collection, I'm creating a new class which inherits from the typcollection:

Public Class CustomerTypePropertyCollection
    Inherits TypePropertyCollection(Of Person)
End Class

I cannot do this because Person (I named it Person here to make it easier) is not known in that solution. It should also be possible to make collection of other types which or not known. That's why I wanted to pass the type of the object and use it that way.

Upvotes: 2

Views: 146

Answers (1)

JonAlb
JonAlb

Reputation: 1720

Dim aList As List(Of PropertyData) = New TypePropertyCollection(Of Type)

This error is because you are attempting to create a TypePropertyCollection of Type 'objectType', objecttype is the variable name of a variable with a type of type .'. You would need a TypePropertyCollection of Type Type Type, not the variable name. Come back to me if there are other issues beyond this.

Upvotes: 1

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