Indirect property notification
- by Carlo
Hello, this question might look a little trivial, but it might not be. I'm just wondering which of the following two cases is better for indirect property notification, or perhaps there is an even better way.
The scenario:
I have two properties, the first one is an object called HoldingObject, the second one is a boolean called IsHoldingObject, which is false if HoldingObject == null, otherwise it's true. I'm just wondering what is the best notification mechanism for IsHoldingObject:
Case (A) - Notify IsHoldingObject changed from the HoldingObject proeperty:
public class NotifyingClass1 : INotifyPropertyChanged
{
private object _holdingObject;
public object HoldingObject
{
get { return _holdingObject; }
set
{
if (_holdingObject != value)
{
_holdingObject = value;
NotifyPropertyChanged("HoldingObject");
// Notify from the property that is being checked
NotifyPropertyChanged("IsHoldingObject");
}
}
}
public bool IsHoldingObject { get { return this.HoldingObject == null; } }
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(string propertyName)
{
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
#endregion
}
Case (B) - Notify IsHoldingObject changed from the IsHoldingObject directly, by setting it to false or true from HoldingObject property:
public class NotifyingClass2 : INotifyPropertyChanged
{
private object _holdingObject;
public object HoldingObject
{
get { return _holdingObject; }
set
{
if (_holdingObject != value)
{
_holdingObject = value;
NotifyPropertyChanged("HoldingObject");
// 1) Set the property here
this.IsHoldingObject = _holdingObject != null;
}
}
}
private bool _isHoldingObject;
public bool IsHoldingObject
{
get { return _isHoldingObject; }
set
{
if (_isHoldingObject != value)
{
_isHoldingObject = value;
// 2) Notify directly from the property
NotifyPropertyChanged("IsHoldingObject");
}
}
}
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(string propertyName)
{
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
#endregion
}
I personally lean to the first one because it requires less code, but I'm not sure how recommendable it is to do that. Let me know if there is another (better) way.
Thanks!
