Improve property monitoring code?

Question

I made a utility debug class in a C# game I'm working on to be able to monitor and watch values of properties. Goes like this:

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public static class Monitor
{
  private static List<object> monitoredObjects;

  public static void Initialize()
  {
   monitoredObjects = new List<object>();

  }

  public static void Watch(object o)
  {
   monitoredObjects.Add(o);
  }

  public static void Unwatch(object o)
  {
   monitoredObjects.Remove(o);
  }

  public static void Draw(RenderWindow app)
  {
                    //Not actual code, I actually draw this in game
   foreach (object o in monitoredObjects)
    Console.WriteLine(o.ToString());
  }
 }

 public class Property
 {
  private object obj;
  private PropertyInfo propertyInfo;

  public override string ToString()
  {
   return propertyInfo.Name + ": " + propertyInfo.GetValue(obj, null).ToString();
  }

  public Property(object o, string property)
  {
   obj = o;
   propertyInfo = o.GetType().GetProperty(property);
  }
 }

Now in order to monitor a property, say my game's FPS, I must do

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Monitor.Watch(new Property(Game, "FPS"));

Wouldn't there be a way to somehow make this simpler to use? Ideally I'd like to be able to do

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Monitor.Watch(Game.FPS);

But since we can't store pointers to value types in C#, I don't know how I would do this. Maybe using closures and lambada expressions? I was suggested this earlier but I'm not sure how to do it. Any other ways to improve this?

Thanks

Answer 1

Personally, what I would do is rework your Monitor class to accept a Func<string> as input, and return a monitoring handle that could be used to "unmonitor" the class.

By doing that, you'd be able to write:

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 var handle = Monitor.Watch( () => Game.FPS.ToString() );
 // later
 Monitor.Unwatch(handle);

This could look something like:

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public static class Monitor
{
    private static Dictionary<IMonitorHandle, Func<string>> monitoredObjects;

    public static void Initialize()
    {
        monitoredObjects = new Dictionary<IMonitorHandle, Func<string>>();
    }

    public static IMonitorHandle Watch(Func<string> o)
    {
        var handle = new MonitorHandle(o);
        monitoredObjects.Add(handle, o);
        return handle;
    }

    public static void Unwatch(IMonitorHandle handle)
    {
        monitoredObjects.Remove(handle);
    }

    public static void Draw(RenderWindow app)
    {
        //Not actual code, I actually draw this in game
        foreach (object o in monitoredObjects.Values)
           Console.WriteLine(o()); // Execute to get value...
    }
}

You'd need to implement some interface for the handle - but this really could be anything, since it's just an object used as a hash table lookup for allowing unsubscription. You only need this to allow "Unwatch" to work, since you need to have some way to remove the delegate, which you'll probably want to define anonymously (as I did above).