protected override void Attach()
{
TrackedObject.PropertyChanged += OnPropertyChanged;
// Scan through the properties to see if we need to
// observe nested objects; for each property add an
// ObjectTracker.
var properties = TrackedObject.GetType()
.GetProperties(BindingFlags.Public | BindingFlags.Instance)
.Where(prop => prop.GetIndexParameters().Length == 0)
.Where(prop => !prop.CustomAttributes.Any(o => o.AttributeType == typeof(DoNotTrackAttribute)))
.ToArray();
foreach (var prop in properties)
{
RefreshPropertyTracker(prop.Name, raiseEvent: false); // Do not raise events on initialization
}
}
private void RefreshPropertyTracker(string propertyName, bool raiseEvent)
{
// Determine the new value
var prop = TrackedObject.GetType().GetProperty(propertyName);
if (prop == null)
{
return; // Was probably an indexer that changed
}
var newValue = prop.GetValue(TrackedObject);
// If no ObjectTracker exists for the property, the old value was null
TrackerToken trackerToken;
object oldValue = null;
if (_propertyTrackers.TryGetValue(propertyName, out trackerToken))
{
// Detach old tracker from old value and remove it
oldValue = trackerToken.Tracker.TrackedObject;
trackerToken.Dispose();
_propertyTrackers.Remove(propertyName);
}
if (newValue != null)
{
// Add a new tracker for the new value
var token = new TrackerToken(newValue, propertyName, Tracker);
_propertyTrackers.Add(propertyName, token);
}
// Notify that property changed
if (raiseEvent)
{
Tracker.RaisePropertyPathChanged(new PropertyPathChangedEventArgs(propertyName, TrackedObject, oldValue, newValue));
}
}
protected override void Attach()
{
if (!(TrackedObject is IEnumerable))
{
throw new ArgumentException($"Failed to track collection changes on object of type {TrackedObject.GetType()}. The object does not implement {nameof(IEnumerable)}.");
}
TrackedObject.CollectionChanged += OnCollectionChanged;
// Scan through the items and create an ObjectTracker
// for each item.
var i = 0;
foreach (var item in TrackedObject as IEnumerable)
{
InsertTrackerAt(i++, item);
}
}