Creating Multiple Extended Controls

Question

I have created an Extended TextBox that Inherits a standard WPF TextBox, what I am now trying to do is create other extended control types like a TextBlock, ListBox, ComboBox etc. All controls will have the same DependencyProperties as shown below so I am trying to find a way to implement this without repeating the DependencyProperty code behind each new extended control.

Public Class ExtendedTextBox
    Inherits TextBox

    Public Shared MandatoryProperty As DependencyProperty = DependencyProperty.Register("Mandatory", GetType(Boolean), GetType(ExtendedTextBox)) 

    Public Shared ReadOnly HasAnyErrorsProperty As DependencyProperty = DependencyProperty.Register("HasAnyErrors", GetType(Boolean), GetType(ExtendedTextBox))
End Class

Answer 1

You could define attached properties that can be set on any UIElement:

Public Class MyProperties
    Public Shared ReadOnly MandatoryProperty As DependencyProperty = DependencyProperty.RegisterAttached("Mandatory", GetType(Boolean), GetType(MyProperties))
    Public Shared Sub SetMandatory(ByVal element As UIElement, ByVal value As Boolean)
        element.SetValue(MandatoryProperty, value)
    End Sub
    Public Shared Function GetMandatory(ByVal element As UIElement) As Boolean
        Return CType(element.GetValue(MandatoryProperty), Boolean)
    End Function
End Class

XAML:

<TextBox local:MyProperties.Mandatory="True" />
<ListBox local:MyProperties.Mandatory="False" />