Error with this

Question

This is probably an already answered questions, but you can imagine the trouble using google to find "c# + this". So I have a class that is trying to trigger an event.
I have the delegate definition
public delegate void OnServingSelectedEvent(object sender, decimal Serving);
class FractionDecimalTextBox:SourceGrid.Cells.Editors.TextBox
    {
        public event OnServingSelectedEvent OnServingSelected;

    public override bool ApplyEdit()
        {
            OnServingSelected(this, Generals.ToDecimal(Control.Text));
            return base.ApplyEdit();

        }
}

I keep getting the error

Object reference not set to an instance of an object.
With

Cannot obtain value of local or argument '<this>' as it is not available at this instruction pointer, possibly because it has been optimized away.    AutocompleteGrid.FoodGrid.FractionDecimalTextBox

shown in the watch page.
As far as I understand it, this is supposed to point to the current object, but I keep getting this error, although it is completely unregular as I have another class where it works great. Does anyone know what I am doing wrong?

brian ashcroft · Answer

Hello I found the error and it was what you described. The event handler assignment was in the wrong constructor. Thank you

Alan · Answer

Generally when firing my own events I check that the event delegate is not null i.e. at least one handler has been added to its invocation list: public override bool ApplyEdit() { if (OnServingSelected != null) OnServingSelected(this Generals.ToDecimal(Control.Text)); return base.ApplyEdit(); } Other than that I can't see anything wrong with the code.

brian ashcroft · Answer

Ok well with more debugging I have found that it is not the this that is the problem but somehow the event declaration is the problem. Yet I do not see how this event is any different than any other the others that I have written. I actually just moved it over. Do you see where the problem is?

Error with "this"