What about Catel.Fody and computed read-only properties change notifications?

In my last post, I covered the implementation of INotifyPropertyChanged interface when using SheepAspect as an AOP library. In the end, I also implemented an approach to notify changes of computed read-only properties. This approach has a downside, the dependent properties discovering process must be done in run-time.

Such a journey recalls us that Catel.Fody didn’t have support for notifying property changes of computed read-only properties. How could such a thing ever be possible? Obvious, “the shoemaker's son always goes barefoot” ;). But don’t worry: the feature is here, moving the dependent properties discovering process to build-time, thanks to Fody.

As you probably know by now, Catel.Fody will rewrite all properties on the DataObjectBase and ViewModelBase. So, if a property is written like this:

public string FirstName { get; set; }

will be weaved into

public string FirstName
{
    get { return GetValue<string>(FirstNameProperty); }
    set { SetValue(FirstNameProperty, value); }
}

public static readonly PropertyData FirstNameProperty = RegisterProperty("FirstName", typeof(string));

But now we added a new feature to Catel.Fody. If a read-only computed property like this one exists:

public string FullName
{
    get { return string.Format("{0} {1}", FirstName, LastName).Trim(); }
}

the OnPropertyChanged method will be also weaved into

protected override void OnPropertyChanged(AdvancedPropertyChangedEventArgs e)
{
    base.OnPropertyChanged(e);
    if (e.PropertyName.Equals("FirstName"))
    {
        base.RaisePropertyChanged("FullName");
    }
    if (e.PropertyName.Equals("LastName"))
    {
        base.RaisePropertyChanged("FullName");
    }
}

This feature is already available in the latest beta package of Catel.Fody.

Try yourself and let us know.