delegates-event-study.linq

<Query Kind="Program" />

void Main()
{
	Console.WriteLine("## firstAction + secondAction ##");
	Action<string> firstAction = x => Console.WriteLine($"firstAction({x})");
	Action<string> secondAction = x => Console.WriteLine($"secondAction({x})");
	(firstAction + secondAction)("derp");
	Console.WriteLine();

	// Output:
	// firstAction(derp)
	// secondAction(derp)

	Console.WriteLine("## firstAction + secondAction - firstAction ##");
	(firstAction + secondAction - firstAction)("derp");
	Console.WriteLine();

	// Output:
	// secondAction(derp)

	Console.WriteLine("## add1Twice(5) ##");
	Func<int, int> add1 = x =>
	{
		Console.WriteLine($"add1({x})");
		return x + 1;
	};
	Func<int, int> add1Twice = add1 + add1;
	Console.WriteLine(add1Twice(5));
	Console.WriteLine();

	// Output:
	// add1(5)
	// add1(5)
	// 6

	Console.WriteLine("## with a delegate ##");
	NumToNum add2 = x => x + 2;
	NumToNum add2Twice = add2 + add2;
	Console.WriteLine(add2Twice(5)); // Output: 7
	Console.WriteLine();

	Console.WriteLine("## exceptions ##");
	Action<string> throwsAction = x => throw new Exception("kaboom");
	Action<string> printAction = x => Console.WriteLine($"printAction({x})");
	try
	{
		(throwsAction + printAction)("derp");
	}
	catch (Exception ex)
	{
		Console.WriteLine($"Caught exception: {ex}");
	}
	Console.WriteLine();

	// Output:
	// Caught exception: System.Exception: kaboom

	Console.WriteLine("## events ##");
	onDerpEvent += x => Console.WriteLine($"before throw: {x}");
	onDerpEvent += x => throw new Exception("kaboom");
	onDerpEvent += x => Console.WriteLine($"after throw: {x}");
	try
	{
		onDerpEvent("foo");
	}
	catch (Exception ex)
	{
		Console.WriteLine($"Caught exception: {ex}");
	}
	Console.WriteLine();

	// Output:
	// before throw: foo
	// Caught exception: System.Exception: kaboom
}

delegate int NumToNum(int x);

event Action<string> onDerpEvent;