Evolving Windows Forms Event Handling With Loosely Coupled Methods

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace FormEventsTests
{
    public partial class FormSettings : Form
    {
        Action<object, EventArgs> changeTitleDelegate;
        Action<object, EventArgs> displayPropsDelegate;

        IList<Person> people;

        public FormSettings ( Action<object, EventArgs> ChangeTitleDelegate )
        {
            this.changeTitleDelegate = ChangeTitleDelegate;

            InitializeComponent ( );

            //  we only need 2 event subscription
            uxSetTitle.Click += new EventHandler ( uxSetTitle_Click );

            //  this form of event we won't need to unsubscribe
            uxCloseSettings.Click += delegate { this.Close ( ); };
        }

        //  evolve how we handle events
        /*  Use an interface to loosely couple to events
         * 
         *  Problem for developers, especially GUI devs, is to remember to
         *  unsubscribe from all events. Even passing a reference to the Owning
         *  object exposes more risks. Limit the risks involved by exposing 
         *  event handlers, or worse, the entire Owning object.
         *  
         *  By interfacing our events, we expose ONLY the Actions. This can 
         *  be thought of as a default action should a certain event occur. Each
         *  implementation would be fairly custom, but the pattern will be 
         *  recognizable. Loosely coupled events will also make it easier to avoid
         *  what I call, 'functionCreep(this)'.
         *  
         *  functionCreep(this) is when you pass an OwnerObject reference to a child
         *  or sibling class. What happens is you start executing functions intimate
         *  to the OwningObject. functionCreep(this) invites exposure of the 
         *  OwningObject's resources.
         *  
         */
        public FormSettings ( IEventPublisher EventOwner )
        {
            //  couple to events
            changeTitleDelegate = EventOwner.ChangeFormTitle;
            displayPropsDelegate = EventOwner.DisplayProperties;

            InitializeComponent ( );
            fillPersonSelector ( );

            uxSetTitle.Click += new EventHandler ( uxSetTitle_Click );
            uxCloseSettings.Click += delegate { this.Close ( ); };

            //  subscribe
            uxPersonSelector.SelectedValueChanged += 
                new EventHandler ( uxPersonSelector_SelectedValueChanged );
        }

        private void fillPersonSelector ( )
        {
            //  get some test data
            people = new List<Person> 
            {
                new Person("David", "Silver City", "TX"),
                new Person("James", "Houston", "TX"),
                new Person("Mandy", "Waco", "TX"),
                new Person("Steven", "Santa Fe", "NM"),
                new Person("Tina", "Edmond", "OK"),
                new Person("Karlena", "Misson", "KS")
            };

            uxPersonSelector.DisplayMember = "Name";
            uxPersonSelector.DataSource = people;
        }

        void uxSetTitle_Click ( object sender, EventArgs e )
        {
            //  pre-process if necessary

            //  invoke delegate
            this.changeTitleDelegate ( this, 
                new GenericEventArgs<string> ( uxFormTitle.Text ) );
        }

        void uxPersonSelector_SelectedValueChanged ( object sender, EventArgs e )
        {
            //  invoke delegate
            this.displayPropsDelegate ( this,
                new GenericEventArgs<Person> ( (Person)uxPersonSelector.SelectedValue ) );
        }
    }

    public class Person
    {
        public Person ( string Name, string City, string State )
        {
            this.City = City;
            this.Name = Name;
            this.State = State;
        }

        public string City { get; set; }
        public string Name { get; set; }
        public string State { get; set; }
    }
}