ControlParameter DevaultValue

Question

I have several parameters for the select statement in an SQL datasource. Two are date values - an optional start date and end date. Here's the definition:

     <asp:ControlParameter ControlID="txtDateFrom" Name="DateFrom" 
          PropertyName="Text" DefaultValue="1/01/1900" Type="DateTime" />
     <asp:ControlParameter ControlID="txtDateTo" Name="DateTo"
          PropertyName="Text" Type="DateTime" />

I can set a DefaultValue for the DateFrom simply. But if the DateTo value hasn't been entered, I want this to default to today's date. Now, I do this in the "Selecting" event handler for the sqlDataSource:

    If Me.txtDateTo.Text = String.Empty Then
        e.Command.Parameters.Item("@DateTo").Value = Date.Today
    End If

Now my question: is there a smarter way do to this - like having an executable expression in the DefaultValue definition itself?