C# properties issue

Question

The other day I bumped into a little problem regarding C#'s properties.

Let's say I have this setup:

public class Point
{
 public float X;
 public float Y;
}

public class Control
{
 protected Point m_Position = new Point();

 public Point Position
 {
  get { return m_Position; }
  set 
  { 
    m_Position = value; }
    // reorganize internal structure..
    reorganize();
  }

  protected reorganize()
  {
   // do some stuff
  }
}

This is all fine, but when it comes to usage, I could write something like:

Control myControl = new Control();
myControl.Position.X = 1.0f;

The thing is, my Control class won't recognize that the Position has been changed because set() hasn't been called.

Is there a way to make Control aware of any Position changes?

Answer 1

There are a number of options in this case:

1. Make the X and Y properties of your Point class immutable. That is, require the user to create a new Point whenever X or Y changes.
2. Setup an event on the Point class and subscribe to it on the Position class. Whenever the Point's X or Y changes, fire the event. The Position class can handle side-effects in the event handler.

In this case, I would suggest option #1