/// <summary>
/// Verifies that the target field is null and sets it to the non-null ISubscription provided
/// or signal an InvalidOperationException if the target field is not null and not the Cancelled
/// instance. In these cases, the new ISubscription is cancelled.
/// </summary>
/// <param name="current">The target field</param>
/// <param name="s">The new ISubscription instance to set</param>
/// <returns>True if successful, false if the target field is not empty</returns>
public static bool Validate <T>(ref IQueueSubscription <T> current, IQueueSubscription <T> s)
{
if (s == null)
{
ReportSubscriptionNull();
return(false);
}
if (current != null)
{
s.Cancel();
if (current != CancelledQueueSubscription <T> .Instance)
{
ReportSubscriptionSet();
}
return(false);
}
current = s;
return(true);
}
