event-study.linq

<Query Kind="Program" />

delegate void SomeDelegate();

static SomeDelegate emptyHandler = delegate {};

event SomeDelegate DefaultSubscriber = () => Console.WriteLine("DefaultSubscriber was called");
event SomeDelegate SubscriberAddedThenRemoved = emptyHandler;
event SomeDelegate DefaultSubscriberWithSubscriberAddedthenRemoved = () => Console.WriteLine("DefaultSubscriberWithSubscriberAddedthenRemoved was called");
event SomeDelegate EmptySubscriber = delegate { };
event SomeDelegate NoSubscribers;

void Main()
{
	DefaultSubscriber();
	
	EmptySubscriber();
	Console.WriteLine("EmptySubscriber did nothing");
	
	DefaultSubscriberWithSubscriberAddedthenRemoved += emptyHandler;
	DefaultSubscriberWithSubscriberAddedthenRemoved -= emptyHandler;
	DefaultSubscriberWithSubscriberAddedthenRemoved();

	SubscriberAddedThenRemoved -= emptyHandler;
	try
	{
		SubscriberAddedThenRemoved();
	}
	catch (NullReferenceException)
	{
		Console.WriteLine("SubscriberAddedThenRemoved throws NullReferenceException");
	}

	try
	{
		NoSubscribers();
	}
	catch (NullReferenceException)
	{
		Console.WriteLine("NoSubscribers() threw NullReferenceException");
	}

	// Output:

	// DefaultSubscriber was called
	// EmptySubscriber did nothing
	// DefaultSubscriberWithSubscriberAddedthenRemoved was called
	// SubscriberAddedThenRemoved throws NullReferenceException
	// NoSubscribers() threw NullReferenceException
}