/// <summary> First property depends on the changed value of the second property.
/// If the second property (subject) is set using SetProperty, then the dependent (observer) property will be notified as well.
/// <example>
/// AddPropertyDependency(() => ThisProperty, () => DependsOnThisProperty);
/// </example>
/// The benefits of this is that we can SEE DIRECTLY in the code which property is related to what.
/// DO NOT use RaiseDependentPropertyChanged because it's HARDER to see which property is related to which property.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <typeparam name="U"></typeparam>
/// <param name="observerProperty"></param>
/// <param name="subjectProperty"></param>
protected void AddPropertyDependency(string dependentName, string sourceName)
{
if (_propertyDependencies == null)
{
_propertyDependencies = new Dictionary <string, HashSet <string> >();
}
//TODO: Check for recursion.
if (dependentName == sourceName)
{
throw new ArgumentOutOfRangeException("dependentProperty", "The dependent and source property cannot be the same.");
}
HashSet <string> dependents = CacheUtility.FindInCacheOrAdd(_propertyDependencies, sourceName, () => new HashSet <string>());
if (!dependents.Contains(dependentName))
{
dependents.Add(dependentName);
}
}