/// <summary>
/// Registers your control as a lifetime user of RefreshBus without you having to implement ILifetimeSubscriber. The implementation instead is the following:
/// 1. If the RefreshBus sees a refresh for any object that was not Published by yourself
/// 1.1 Refreshbus will check your originalObject still Exists
/// 1.2 If not then your ParentForm will be .Closed
/// 2. If the RefreshBus sees a refresh for your object specifically (that was not published by yourself)
/// 2.1 SetDatabaseObject will be called with the new state (in memory as it was passed to Publish) of the object
///
/// <para>Note: you can subscribe to EstablishSelfDestructProtocol in your SetDatabaseObject method if you want without worrying about repeat subscriptions but know that only
/// the first subscription is respected therefore you should NOT change the database object to a different one</para>
///
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="user"></param>
/// <param name="activator"></param>
/// <param name="originalObject"></param>
public void EstablishSelfDestructProtocol <T>(RDMPSingleDatabaseObjectControl <T> user, IActivateItems activator, T originalObject) where T : DatabaseEntity
{
//they already subscribed to self destruct protocols - repeat subscriptions can be caused by registering in SetDatabaseObject and then refresh callbacks triggering more calls to SetDatabaseObject within the Controls lifetime
var existingSubscription = _selfDestructors.OfType <SelfDestructProtocol <T> >().SingleOrDefault(s => s.User == user);
//they have subscribed for this before
if (existingSubscription != null)
{
if (!existingSubscription.OriginalObject.Equals(originalObject))//wait a minute! they subscribed for a different object!
{
throw new ArgumentException(
"user " + user +
" attempted to subscribe twice for self destruct but with two different objects '" +
existingSubscription.OriginalObject + "' and '" + originalObject + "'", "user");
}
else
{
return;//they subscribed for the same object it's all ok
}
}
//The anonymous refresh callback that updates the user when the object changes or deletes
var subscriber = new SelfDestructProtocol <T>(user, activator, originalObject);
//keep track of the self destructors independently of the subscription list
_selfDestructors.Add(subscriber);
//subscribe them now
Subscribe(subscriber);
var parentForm = user.ParentForm;
if (parentForm == null)
{
throw new ArgumentException("Control must have an established ParentForm, you should not attempt to establish a lifetime subscription until your control is loaded (i.e. don't call this in your constructor)", "c");
}
//when their parent closes we unsubscribe them
parentForm.FormClosed += (s, e) =>
{
Unsubscribe(subscriber);
var toRemove = _selfDestructors.OfType <SelfDestructProtocol <T> >().Single(u => u.User == user);
_selfDestructors.Remove(toRemove);
};
}
public SelfDestructProtocol(RDMPSingleDatabaseObjectControl <T> user, IActivateItems activator, T originalObject)
{
_activator = activator;
User = user;
OriginalObject = originalObject;
}
