Question

I am learning Events and Delegates & started with multiple events now. Just that the docs does not supply any information or code example to raising events defined in this manner.Below you can find a simple example

Sample Code

public class Person
    {
        private string _name;
        private string _phone;

        public string Name
        {
            get { return _name; }
            set
            {
                _name = value;
            }
        }

        public string Phone
        {
            get { return _phone; }
            set
            {
                _phone = value;
            }
        }

        protected EventHandlerList EventDelegateCollection = new EventHandlerList();

        //define the event key
        static readonly object PhoneChangedEventKey = new object();
        public event EventHandler PhoneChanged
        {
            add
            {
                EventDelegateCollection.AddHandler(PhoneChangedEventKey, value);
            }
            remove
            {
                EventDelegateCollection.RemoveHandler(PhoneChangedEventKey, value);
            }
        }
    }

I would like to raise the event when the Phone number is set. if anything sounds funky and don’t understand what i am talking about see here

Update

I would like to clear some doubts here. There are Two ways you can actually subscribe and invoke the event handlers the classical pattern(as described here) where the steps are

• Define the delegate that acts as signature for subscribed methods.
• Define the Event that delegates
• Define the method that raises the handlers
  note: above method creates field for every event hence consumes more memory reference

Event Property is another way where you do below

• Define a object that acts as Key to a event
• Define a method to add and remove handlers for the event from the event invocation list
• Raise the event by determining event handlers based on event key

Answer 1

This is how you should actually raise it

Code

public class Person
{
    private string _name;
    private string _phone;

    public string Name
    {
        get { return _name; }
        set
        {
            _name = value;
        }
    }

    public string Phone
    {
        get { return _phone; }
        set
        {
            _phone = value;
            //Invoke the Handlers now
            OnPhoneChanged();
        }
    }

    protected EventHandlerList EventDelegateCollection = new EventHandlerList();
    static readonly object PhoneChangedEventKey = new object();
    public event EventHandler PhoneChanged
    {
        add
        {
            EventDelegateCollection.AddHandler(PhoneChangedEventKey, value);
        }
        remove
        {
            EventDelegateCollection.RemoveHandler(PhoneChangedEventKey, value);
        }
    }

    private void OnPhoneChanged()
    {
        EventHandler subscribedDelegates = (EventHandler)this.EventDelegateCollection[PhoneChangedEventKey];
        subscribedDelegates(this, EventArgs.Empty);
    }
}