[c#] How can I make my own event in C#?

How can I make my own event in C#?

I have a full discussion of events and delegates in my events article. For the simplest kind of event, you can just declare a public event and the compiler will create both an event and a field to keep track of subscribers:

public event EventHandler Foo;

If you need more complicated subscription/unsubscription logic, you can do that explicitly:

public event EventHandler Foo
{
    add
    {
        // Subscription logic here
    }
    remove
    {
        // Unsubscription logic here
    }
}

You can declare an event with the following code:

public event EventHandler MyOwnEvent;

A custom delegate type instead of EventHandler can be used if needed.

You can find detailed information/tutorials on the use of events in .NET in the article Events Tutorial (MSDN).

to do it we have to know the three components

1. the place responsible for firing the Event
2. the place responsible for responding to the Event

3. the Event itself

   a. Event

   b .EventArgs

   c. EventArgs enumeration

now lets create Event that fired when a function is called

but I my order of solving this problem like this: I'm using the class before I create it

1. the place responsible for responding to the Event

   NetLog.OnMessageFired += delegate(object o, MessageEventArgs args) 
   {
           // when the Event Happened I want to Update the UI
           // this is WPF Window (WPF Project)  
           this.Dispatcher.Invoke(() =>
           {
               LabelFileName.Content = args.ItemUri;
               LabelOperation.Content = args.Operation;
               LabelStatus.Content = args.Status;
           });
   };
   

NetLog is a static class I will Explain it later

the next step is

2. the place responsible for firing the Event

   //this is the sender object, MessageEventArgs Is a class I want to create it  and Operation and Status are Event enums
   NetLog.FireMessage(this, new MessageEventArgs("File1.txt", Operation.Download, Status.Started));
   downloadFile = service.DownloadFile(item.Uri);
   NetLog.FireMessage(this, new MessageEventArgs("File1.txt", Operation.Download, Status.Finished));
   

the third step

3. the Event itself

I warped The Event within a class called NetLog

public sealed class NetLog
{
    public delegate void MessageEventHandler(object sender, MessageEventArgs args);

    public static event MessageEventHandler OnMessageFired;
    public static void FireMessage(Object obj,MessageEventArgs eventArgs)
    {
        if (OnMessageFired != null)
        {
            OnMessageFired(obj, eventArgs);
        }
    }
}

public class MessageEventArgs : EventArgs
{
    public string ItemUri { get; private set; }
    public Operation Operation { get; private set; }
    public Status Status { get; private set; }

    public MessageEventArgs(string itemUri, Operation operation, Status status)
    {
        ItemUri = itemUri;
        Operation = operation;
        Status = status;
    }
}

public enum Operation
{
    Upload,Download
}

public enum Status
{
    Started,Finished
}

this class now contain the Event, EventArgs and EventArgs Enums and the function responsible for firing the event

sorry for this long answer