SYSK 28: Do you know about ‘Anonymous Methods’? If not, read on…

  • Article

Have you ever created a delegate that has just a couple of lines of code?  If yes, in .NET 2.0 you could’ve put that code right “in-line” as demonstrated below:

class MyForm : Form
{
ListBox listBox;
TextBox textBox;
Button addButton;

   public MyForm() {
listBox = new ListBox(...);
textBox = new TextBox(...);
addButton = new Button(...);
addButton.Click += delegate {
listBox.Items.Add(textBox.Text);
};
}
}

You can pass an anonymous method into any method that accepts the appropriate delegate type as a parameter.

To pass a parameter to an anonymous delegate, use the following syntax:
SomeDelegate del = delegate(string arg)
{
MessageBox.Show(arg);
};
del("Hello, World!");  

or

button.Click += delegate(object sender, EventArgs e) { MessageBox.Show(((Button)sender).Text); };

MSDN has a comprehensive article on anonymous methods.  Check it out at http://msdn.microsoft.com/msdnmag/issues/04/05/C20/