/// <summary>
/// Call this function just before setting the field that this
/// sentry controls.
/// </summary>
/// <remarks>
/// Any computed fields that depend upon this field will become
/// out-of-date.
/// </remarks>
public void OnSet()
{
// Verify that computeds are not changing observables, as that
// could be a logical circular dependency.
if (Computed.GetCurrentUpdate() != null)
{
Debug.Assert(false, "An observable was changed while updating a computed.");
}
// When an observable field changes,
// its computeds become out-of-date.
MakeDependentsOutOfDate();
}
/// <summary>
/// Establishes a relationship between this precedent and the currently
/// updating dependent.
/// </summary>
internal void RecordDependent()
{
// Get the current dependent.
Computed update = Computed.GetCurrentUpdate();
if (update != null && !Contains(update) && update.AddPrecedent(this))
{
if (Insert(update))
{
GainDependent();
}
}
else if (!Any())
{
// Though there is no lasting dependency, someone
// has shown interest.
GainDependent();
LoseDependent();
}
}