Making web control values persist [Resolved]

I just made the world's simplest Web Control.

VB Code:

Protected Overrides Sub Render(ByVal Output As HtmlTextWriter)
            Output.Write("<b><u>" & _writewhat & "</u></b>")
        End Sub
 
        Public Property WriteWhat() As String
            Get
                Return _writewhat
            End Get
            Set(ByVal Value As String)
                _writewhat = Value
            End Set
        End Property

See?

But I have no idea how I can make the values of these persist on postbacks.

Either there's some code I have to write, or I'm overlooking something simple.

So, how?

VB Code:

Private _writewhat As String = "default if not assigned"
 
Protected Overrides Sub Render(ByVal Output As HtmlTextWriter)
            Output.Write("<b><u>" & [b]Me.WriteWhat[/b] & "</u></b>")
        End Sub
 
        Public Property WriteWhat() As String
            Get
                [b]If Me.ViewState("writewhat") Is Nothing Then[/b]
                    Return _writewhat
                [b]Else
                    Return Me.ViewState("writewhat")
                End If[/b]
            End Get
            Set(ByVal Value As String)
                _writewhat = Value
                [b]Me.ViewState.Add("writewhat",Value)[/b]
            End Set
        End Property

OK... I've understood that, thanks.

One more question, though:

You're doing a check like this:

VB Code:

If Me.ViewState("writewhat") Is Nothing Then

What exactly is this doing?

Is it not possible to just do a:

VB Code:

Public Property WriteWhat() As String
            Get
                Return CType(ViewState("WriteWhat"), String)
 
            End Get
            Set(ByVal Value As String)
                ViewState("WriteWhat") = Value
            End Set
        End Property

?

No, wait, I did understand that line, my question is simply, can I do it the second way I just posted?

No... ok, never mind. I understood.

Yea, you could do that.... doesn't matter...

I only wonder how expensive a Ctype operation is... so even though it looks cleaner, you should at least try invoking Ctype only after you have checked to see there is a reason to...

VB Code:

Public Property WriteWhat() As String
            Get
                If Me.ViewState("writewhat") Is Nothing Then
                    Return _writewhat
                Else
                    Return Ctype(Me.ViewState("writewhat"),String)
                End If
            End Get

For that matter, ViewState seems to be pretty expensive too. So why not go for the whole shebang :D