Custom Control

[Memnoch1207]

Okay, here is the dilemma.
I have created a custom control that consists of a textbox and an optional required field validator.
Everything works fine except for one minor problem.

I have overridden some of the properties, such as Font, BackColor, BorderStyle, etc.. and have made these properties invisible in the properties window, using <Browsable(False)> _.

The problem is, in the code-behind (using VS.NET) Intellisense still displays the hidden properties.
All the examples I have seen say to use the EditorBrowsable(EditorBrowsableState.Never) attribute to prevent Intellisense from displaying it, but this isn't working....

Here's a sample control I created to test this.

Imports System
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.ComponentModel
Imports System.Drawing


Public Class MyTextBox
    Inherits TextBox

    Private txtBox As TextBox

    Public Sub New()
        txtBox = New TextBox
    End Sub

    Protected Overrides Sub render(ByVal writer As HtmlTextWriter)
        MyBase.Render(writer)
    End Sub
 
    Browsable - prevents the property from being seen in the properties window...This works

    EditorBrowsable - prevents the property from being referenced in intellisense 
    in the code-behind...This doesn't work!

    Obsolete - Prevents a developer from using this property. 
    If the developer tries to use this property in the code-behind
    and compile it. The message is supposed to display in the 
    task list as an error.
    "This property isn't supported."...This doesn't work!  

    <Browsable(False), _
    EditorBrowsable(EditorBrowsableState.Never), _
    Obsolete("This property isn't supported.", True)> _
    Public Overrides Property BackColor() As Color
        Get
            Return Nothing
        End Get
        Set(ByVal Value As Color)
            txtBox.BackColor = Nothing
        End Set
    End Property

End Class

Any ideas why???

[nemaroller]

Well, I noticed if you use a non-existing property name, the intended effect occurs.

If you inherit from a control, and try to suppress what is declared publicly browsable in the parent, the intended effect does not occur.

In the case of textbox, (and I also tried Label), even though the property is declared Overridable, it doesn't seem you can suppress the MetaTag (EditorBrowsable) associated with that property in the parent.


Strangely, of the three you presented, this 'glitch' only happens with the EditorBrowsable attribute. I'm not sure if its a bug, or its has to do with how the EditorBrowsable attribute is defined in the server controls that implement it, that prevent it from working.

So after trying all that, and using the control from a dll instead of within the project, i googled and found this:

http://www.dotnet247.com/247referenc...29/148631.aspx


Bottom line: I'm guessing there are some undocumented attributes (or perhaps just reasons) that prevent inheriting children from hiding properties declared as browseable in the parent.

As far as a workaround, well, you could make your inherited control a composite control (webcontrol) that internally encompasses a textbox, and only expose the properties that are needed. I'm pretty sure for example, the WebControl class does not expose a BackColor property.

[Magiaus]

public class lite : System.Web.UI.Control

[Memnoch1207]

Yes, WebControl exposes a BackColor Property among others.
My assumption/test is you can override the inherited properties for the WebControl base class, but you can't suppress them from showing up in intellisense.

I did a test and created a base control (myTextBox) which inherited from the WebControl class. Then I inherited my base control to create a custom control (myTextBox2).

I did an override of the WebControls BackColor property in my base control (myTextBox), and I was able to suppress the BackColor property in my custom Control (myTextBox2) and prevent the BackColor property from showing up in intellisense.

Example:

Public Class myTextBox
   Inherits WebControl
 
   [color=red]Override the WebControls BackColor Property[/color]
   Public Overrides Property BackColor() As Color
      Get
         'code here
      End Get
      Set(ByVal Value As Integer)
         'code here
      End Set
   End 
End Class

Then I inherit myTextBox

Public Class myTextBox2
   Inherits myTextBox
   
   'I was able to suppress the BackColor property from
   'showing up in intellisense by doing this.
 
   [color=red]Override myTextBoxes BackColor property[/color]
   <Browsable(False), _
    EditorBrowsable(EditorBrowsableState.Never), _
    Obsolete("This control does not support this property.", True)> _
   Public Overrides Property BackColor() As Color
      Get
         'code here
      End Get
      Set(ByVal Value As Integer)
         'code here
      End Set
   End Property
End Class

[Magiaus]

new internal System.Drawing.Color BackColor{get{;}}


you the assembly dev could see backcolor byt no one else should be able to. But then again I don't think that really works either. Your best be is to either inherit from control or from the interfaces IParssorAccesory, IStateManager, IComponet, IDataBind. Of cour the you have to handle state and whast not

[nemaroller]

Originally posted by Memnoch1207
......

So you were able to solve this then by simply not inheriting your custom 'textbox' from the System.Web.UI.WebControls.TextBox, but rather the WebControl class. Which is how you create a composite control btw.

So perhaps then, all server controls, including Label, Checkbox, etc, have these limiting attributes in their decleration, that disallow suppression of the EditorBrowseable attribute.

I find that pretty strange the .Net framework was made this way.

[Memnoch1207]

It didn't matter if I inherited from WebControl or WebControl.TextBox.

Apparently you can't suppress the webcontrols properties directly. I was able to solve it by creating a class that inherits webcontrol and overrides the webcontrols properties.
Then creating another class that inherits from the first class I created, then overriding it's properties.