Tim Van Wassenhove

I find it frustrating that data binding does not really support Nullable<T>. Anyway, it’s relatively easy to workaround this shortcoming:

public partial class Form1 : Form
{
 private MyDataSource myDataSource;

 public Form1()
 {
   InitializeComponent();

   this.myDataSource = new MyDataSource();
   this.textBox1.DataBindings.Add("Text", this.myDataSource, "Double", true);
   this.textBox1.DataBindings["Text"].Parse += this.Text_Parse;
 }

 void Text_Parse( object sender, ConvertEventArgs e )
 {
  if( e.Value == null || e.Value.ToString().Length == 0 )
  {
   e.Value = null;
  }
 }

 private void buttonTellMe_Click(object sender, EventArgs e)
 {
  if (this.myDataSource.Double.HasValue)
  {
   MessageBox.Show("The double is: " + this.myDataSource.Double);
  }
  else
  {
   MessageBox.Show("The double is null");
  }
 }
}

class MyDataSource
{
 private double? _double;

 public double? Double
 {
  get { return this._double; }
  set { this._double = value; }
 }
}