Delegates , Events , Publishing , subscribing
this is something new I have tried here , all explanations are in comments. As they say in OOP , have smart coupling…
Just copy the below code in your visual studio :
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
namespace _2112014
{
class Program
{
static void Main(string[] args)
{
#region Delegate,action
//multicast delegate example go to UseDelegate class to see implemenation
//UseDelegate UD = new UseDelegate(4, 5);
//calling action delegate , action delegate is kept outside function
//UseDelegate UD = new UseDelegate();
//UD.MyAction(5, 5);
#endregion
#region eventhandler example on filesystem
// event handler is delegate which sits between suscriber and publisher
// just mouse over the event -> watcher.created above and see what kind of event handler it excepts
// check out the parameter
// and create same signature method in same class or other class and pass the method
//var watcher = new FileSystemWatcher(“C:\\Users\\rohan\\Desktop\\Event”);
//watcher.EnableRaisingEvents = true;
//watcher.Created += new FileSystemEventHandler(OnCreated);
//watcher.Deleted += OnDeleted;
//watcher.Changed += OnChanged;
#endregion
#region Event suscribing Car class event
//Car C = new Car(); //creating instance of that publisher class — Car
//C.change += ReturnWarningSign;//suscribing to event , telling if this event occurs then run this function
//C.pspeed = 89; //making the event fire
#endregion
// Console.ReadLine(); //so program doesnot close console screen
}
//public static void ReturnWarningSign() //fire this event when event occurs in publisher class
//{
// Console.WriteLine(“reduce speed”);
// Console.ReadLine();
//}
#region EventFunctions
private static void OnChanged(object sender, FileSystemEventArgs e)
{
Console.WriteLine(“{0} : {1} “, e.ChangeType, e.Name);
}
static void OnDeleted(object sender, FileSystemEventArgs e)
{
Console.WriteLine(“{0} : {1} “, e.ChangeType, e.Name);
}
static void OnCreated(object obj, FileSystemEventArgs e)
{
Console.WriteLine(“{0} : {1} “, e.ChangeType, e.Name);
}
#endregion
}
}
same namespace
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace _2112014
{
public class UseDelegate
{
// TODO: Complete member initialization
//action and lamda expression
//action and func are types of delegates , action is used when you dont know exact signature
//action accepts 16 input parameters and no return types , while func can have return type
//lamda expression => is used to make functions on fly like below example , please study the syntax
public Action<int, int> MyAction = (int a, int b) => { Console.WriteLine(a + b); };
public UseDelegate()
{
}
public UseDelegate(int x , int y)
{
//creating multicast deligate — a deligate which contains more than one function
//# region mathematical function
Calculate MulticastCalculateDelegateObject = Add;
MulticastCalculateDelegateObject += Subtract;
MulticastCalculateDelegateObject += Divide;
MulticastCalculateDelegateObject += Multiply;
MulticastCalculateDelegateObject(x, y);
}
public delegate string Calculate(int x , int y);
#region MathematicalFunction
public string Add(int x, int y)
{
return ((x + y).ToString());
}
public string Multiply(int x, int y)
{
return ((x * y).ToString());
}
public string Divide(int x, int y)
{
return ((x / y).ToString());
}
public string Subtract(int x, int y)
{
return ((x — y).ToString());
}
#endregion
}
}
public class UseDelegate
{
// TODO: Complete member initialization
//action and lamda expression
//action and func are types of delegates , action is used when you dont know exact signature
//action accepts 16 input parameters and no return types , while func can have return type
//lamda expression => is used to make functions on fly like below example , please study the syntax
public Action<int, int> MyAction = (int a, int b) => { Console.WriteLine(a + b); };
public UseDelegate()
{
}
public UseDelegate(int x , int y)
{
//creating multicast deligate — a deligate which contains more than one function
//# region mathematical function
Calculate MulticastCalculateDelegateObject = Add;
MulticastCalculateDelegateObject += Subtract;
MulticastCalculateDelegateObject += Divide;
MulticastCalculateDelegateObject += Multiply;
MulticastCalculateDelegateObject(x, y);
}
public delegate string Calculate(int x , int y);
#region MathematicalFunction
public string Add(int x, int y)
{
return ((x + y).ToString());
}
public string Multiply(int x, int y)
{
return ((x * y).ToString());
}
public string Divide(int x, int y)
{
return ((x / y).ToString());
}
public string Subtract(int x, int y)
{
return ((x — y).ToString());
}
#endregion
}
same namespace
public class Car
{
public Car()
{
}
//created to learn about creating event , firing event , suscribing event to other class
//logic if speed greater than 50 then fire event
//declare an event
public event Action change;
private double speed;
public double pspeed
{
get {
return speed;
}
set { speed = value;
if (speed>50)
{
if (change != null)
{
change(); //fire the event if the condition satisfies
}
}
}
}
}
