DelegateClosureTestsC#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace World
{
    public delegate double MathAction(double n);

    public delegate string ClosureDemo();

    public delegate void MyEventHandler(object source, EventArgs arg);
    class DelegateTest
    {
        public double Double(double m)
        {
            return m * 2;
        }

        private int forClosure = 3;

        public void Tests()
        {
            int freeVariable = 5;

            // 1. Function
            MathAction d1 = new MathAction(Double);
            Console.WriteLine(d1(3.14));

            // 2. Anonimous function
            d1 = delegate(double x) { return x * x + freeVariable + this.forClosure; };
            Console.WriteLine(d1(3.14));

            // 3. Lambda expression. No return
            d1 = (x) => x * x * x + freeVariable + this.forClosure;
            Console.WriteLine(d1(3.14));

            // 3.2 Lambda statement. There is return
            d1 = (x) => { return x * x * x + freeVariable + this.forClosure;};
            Console.WriteLine(d1(3.14));

            freeVariable = 7;

            Console.WriteLine("++++++++++++++++ Closure+++++++++++++");
            Console.WriteLine(Calculate(d1, 3.14));
            Console.WriteLine("+++++++++++++++++++++++");

            string name = "Stoyan";
            int age = 52;
            ClosureDemo stoyan = delegate() { return name + age.ToString(); };

            Console.WriteLine(TestClosure(stoyan));


            name = "Alex";
            age = 22;
            ClosureDemo alex = delegate() { return name + age.ToString(); };

            Console.WriteLine(TestClosure(alex));
        }

        public double Calculate(MathAction action, double num)
        {
            return action(num);
        }

        public string TestClosure(ClosureDemo c) { // MathAction
            return c();
            // MathAction action;

        }
    }
}