-event- can only appear on the left hand side of += or -=

Question

I have an event in a loop. I am trying to prevent the same method being added to an event more than once. I\'ve implemented the add and remove acce

Answer 1

I can't tell from your post if you are trying to raise the event from a derived class or not, but one thing I've found is that you can't define an event in a base class and then raise it (directly) in a derived class, for some reason that isn't real clear to me yet.

So I define protected functions in base classes to raise events (that are defined in those base classes), like this:

// The signature for a handler of the ProgressStarted event.
// title: The title/label for a progress dialog/bar.
// total: The max progress value.
public delegate void ProgressStartedType(string title, int total);

// Raised when progress on a potentially long running process is started.
public event ProgressStartedType ProgressStarted;

// Used from derived classes to raise ProgressStarted.
protected void RaiseProgressStarted(string title, int total) {
    if (ProgressStarted != null) ProgressStarted(title, total);
}

Then in the derived class, I call RaiseProgressStarted(title, total) instead of calling ProgressStarted(title, total).

It seems like kind of the long way around. Maybe someone else knows of a better way around this problem.