Question

I was wondering how I could set an EventHandler for a button click so that it would replace all other handlers for this objets. Ideally it would be something of the likes of:

button1.Click = MessageBox.Show("Run just this!"); //Yes, the '=' instead of the '+='.

This is because button1 already has a few click events, and I want to, in the determinated situation, overwrite all the other ones.

More examples:

button1.Click += MessageBox.Show("Event #1 has been triggered!");
button1.Click += MessageBox.Show("Event #2 and #1 have been triggered!");
button1.Click = MessageBox.Show("Event #3, and only #3, has been triggered!");

Answer 1

you can try this…

there is a solution on the MSDN forums. The sample code below will remove all Click events from button1.

you can keep one event on button …..

public partial class Form1 : Form
{
        public Form1()
        {
            InitializeComponent();

            button1.Click += button1_Click;
            button1.Click += button1_Click2;
            button2.Click += button2_Click;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            MessageBox.Show("Hello");
        }

        private void button1_Click2(object sender, EventArgs e)
        {
            MessageBox.Show("World");
        }

        private void button2_Click(object sender, EventArgs e)
        {
            RemoveClickEvent(button1);
        }

        private void RemoveClickEvent(Button b)
        {
            FieldInfo f1 = typeof(Control).GetField("EventClick", 
                BindingFlags.Static | BindingFlags.NonPublic);
            object obj = f1.GetValue(b);
            PropertyInfo pi = b.GetType().GetProperty("Events",  
                BindingFlags.NonPublic | BindingFlags.Instance);
            EventHandlerList list = (EventHandlerList)pi.GetValue(b, null);
            list.RemoveHandler(obj, list[obj]);
        }
    }
}