Remove eventHandler that was added using lambda expression
I have a control that I added an event to. However, I needed to pass some extra parameters to the event method, so I use lambda expression like it was described here:
Pass parameter to EventHandler
comboBox.DropDown += (sender, e) => populateComboBox(sender, e, dataSource, selectedItem);
But this event should only fire the first time the conditions are met after what it should be removed.
Doing this doesn't work:
comboBox.DropDown -= (sender, e) => populateComboBox(sender, e, dataSource, selectedItem);
So the question is, is there a way to remove this method?
I've seen this:
How to remove all event handlers from a control
But I can't get it working for ComboBox DropDown event.
The problem that it's not getting removed is because you're giving a new lambda expression when removing it. You need to keep the reference of delegate created by Lambda expression to remove it from the control.
EventHandler handler = (x, y) => comboBox1_DropDown(x, y);
comboBox1.DropDown += handler;
It will work simply like:
comboBox1.DropDown -= handler;
via reflection:
private void RemoveEvent(ComboBox b, EventHandler handler)
{
EventInfo f1 = typeof(ComboBox).GetEvent("DropDown");
f1.RemoveEventHandler(b, handler);
}
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