/// <summary>
/// Adds the <see cref="SourceItemChanged(object, ItemChangedEventArgs)"/> event handler to the
/// <see cref="SourceItem"/>'s <see cref="Changed"/> event.
/// </summary>
/// <returns>A Result containing the result of the operation.</returns>
/// <threadsafety instance="true"/>
public virtual Result SubscribeToSource()
{
Result retVal = new Result();
if (Source == ItemSource.Item)
{
sourceItemLock.EnterWriteLock();
try
{
SourceItem.Changed += SourceItemChanged;
SourceItem.SubscriptionsChanged();
IsSubscribedToSource = true;
}
finally
{
sourceItemLock.ExitWriteLock();
}
}
else if (Source == ItemSource.Provider)
{
providerLock.EnterWriteLock();
try
{
if (Provider is ISubscribable)
{
((ISubscribable)Provider).Subscribe(this, value => ChangeValue(value));
IsSubscribedToSource = true;
}
else
{
retVal.AddError("Unable to subscribe to source; the source Item Provider is not subscribable.");
}
}
finally
{
providerLock.ExitWriteLock();
}
}
else
{
retVal.AddError("Unable to subscribe to source; the source Item is either not specified or hasn't been resolved.");
}
return(retVal);
}
