Question

I couldn’t find the + operator in Reflector under Delegate or MulticastDelegate.

I’m trying to figure out how this doesn’t need a cast:

Action a = () => Console.WriteLine("A");
Action b = () => Console.WriteLine("B");

Action c = a + b;

But this does:

Action a = () => Console.WriteLine("A");
Action b = () => Console.WriteLine("B");

Action c = (Action)MulticastDelegate.Combine(a, b);

In the first sample is the cast just done under the covers?

Answer 1

Taking the following example:

class Program
{
    static void Main(string[] args)
    {
        Test1();
        Test2();
    }

    public static void Test1()
    {
        Action a = () => Console.WriteLine("A");
        Action b = () => Console.WriteLine("B");

        Action c = a + b;
        c();
    }

    public static void Test2()
    {
        Action a = () => Console.WriteLine("A");
        Action b = () => Console.WriteLine("B");

        Action c = (Action)MulticastDelegate.Combine(a, b);
        c();
    }
}

Then looking at it with ILSpy:

internal class Program
{
    private static void Main(string[] args)
    {
        Program.Test1();
        Program.Test2();
    }
    public static void Test1()
    {
        Action a = delegate
        {
            Console.WriteLine("A");
        };
        Action b = delegate
        {
            Console.WriteLine("B");
        };
        Action c = (Action)Delegate.Combine(a, b);
        c();
    }
    public static void Test2()
    {
        Action a = delegate
        {
            Console.WriteLine("A");
        };
        Action b = delegate
        {
            Console.WriteLine("B");
        };
        Action c = (Action)Delegate.Combine(a, b);
        c();
    }
}

Seems that they do the exact same thing, just C# is providing some syntactic sugar in the first test.