Question

I’m trying to learn about events and I have a task to create EventArgs info classes, derived from EventArgs. I’m not sure what this means and how I should do?

Answer 1

Event arguments are made to deliver additional information about the event that fired, for instance a value that was changed or an item’s ID. The signature of event handlers contains a sender and EventArgs.

Since EventArgs are pretty empty, you usually implement your own class:

public event EventHandler<FooEventArgs> Foo; // produces handler(object sender, FooEventArgs e)

public sealed class FooEventArgs : EventArgs
{
    public FooEventArgs(int bar)
    {
        this.Bar = bar;
    }

    public int Bar { get; private set; }
}

This is just a normal subclass like you would create everywhere else. If you do not need to pass more information, use EventArgs.Empty (static field).