This Old Code

I was looking for a way to pass a parameter by reference today.  More specifically the setter.

I found a couple interesting blog posts

http://geekswithblogs.net/akraus1/archive/2006/02/10/69047.aspx

notice the comment by Tedesco.

He offers a nice way to do this via an anonymous delegate.

    public delegate void InsertString( System.String param );
    public partial class Bird
    {
        public void FileToDb( int x )
        {
            FillEntityColumn( delegate( System.String value )
            {
                tExtra.Text = value;
            } );
        }
    }  

So we actual pass the FillEntityColumn method an anonymous delegate which then sets the property.

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        testme(TextBox1.Text)
    End Sub
    Sub testme(ByRef s As String)
        s = "hello"
    End Sub

which a commenter on http://musingmarc.blogspot.com/2006/04/tale-of-two-implementations.html eluded to.  But in vb you still cannot pass a Property by reference, at least not really.  Take a look what vb generates into il.

    Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs)
        Dim VB$t_ref$S0 As TextBox = Me.TextBox1
        Dim VB$t_string$S0 As String = VB$t_ref$S0.Text
        Me.testme((VB$t_string$S0))
        VB$t_ref$S0.Text = VB$t_string$S0
    End Sub