What does "x.OnSpeak += (s, e)" mean?

Question

• I know that's the "e" for the event args, but what does "s" mean here and the "+= ( , ) =>" ?

• Is there's any other alternative implementations ?

  class Program
  {
   static void Main(string[] args)
     {
       var x = new Animal();
       x.OnSpeak += (s, e) => Console.WriteLine("On Speak!");
       x.OnSpeak += (s, e) => Console.WriteLine(e.Cancel ? "Cancel" : "Do not cancel");
  
       Console.WriteLine("Before");
       Console.WriteLine(string.Empty);
  
       x.Speak(true);
       x.Speak(false);
  
      Console.WriteLine(string.Empty);
      Console.WriteLine("After");
  
      Console.Read();
     }
  
   public class Animal
   {
    public event CancelEventHandler OnSpeak;
    public void Speak(bool cancel)
     {
       OnSpeak(this, new CancelEventArgs(cancel));
     }
   }
  }
  

Answer 1

This is often referred to as an "inline event", and is just another way of running particular code when the OnSpeak event fires.

x.OnSpeak += (s, e) => Console.WriteLine("On Speak!");

The s is the sender, and the e is the event arguments.

You could rewrite your code like this, which may be more familiar-looking:

x.OnSpeak += OnSpeakEvent;

private static void OnSpeakEvent(object s, CancelEventArgs e)
{
    Console.WriteLine("On Speak!");
}