TBoldSubscriber¶

TBoldSubscriber is an abstract superclass for classes subscribing to events.

Declaration¶

TBoldSubscriber = class(TBoldMemoryManagedObject)

Hierarchy¶

TObject
TBoldMemoryManagedObject
TBoldSubscriber
Direct subclasses
TBoldAbstractDeriver
TBoldComClientSubscriber
TBoldComServerSubscriber
TBoldFollowerSubscriber
TBoldLogReceiverSubscriber
TBoldPassthroughSubscriber
TBoldRegion

Description¶

Concrete classes become subscribable either by subclassing TBoldSubscriber, e.g. TBoldFollower, or by using a TBoldPassthroughSubscriber.

Properties¶

Name	Summary	Notes
ContextString		read-only
HandlesExtendedEvents		read-only

ContextString¶

property ContextString: string;

This property returns a string describing the subscriber. The default implementation returns '', this can be changed by overriding GetContextString.

HandlesExtendedEvents¶

property HandlesExtendedEvents: Boolean;

This property is used by the subscription mechanism to know if Receive or ReceiveExtended should be called when notifying a subscriber.

Note

Default is to return false, override the GethandlesExtendedEvents to change this

Methods¶

Name	Summary	Notes
Answer		protected, virtual
CancelAllSubscriptions
CloneSubscriptions
Destroy		override
GetContextString		protected, virtual
GetHandlesExtendedEvents		protected, virtual
Receive	This method is called each time a event occurs that the subscriber holds a subscription to occurs.	protected, abstract
ReceiveExtended		protected, virtual

Answer¶

function Answer(Originator: TObject; OriginalEvent: TBoldEvent; RequestedEvent: TBoldRequestedEvent; const Args: array of const; Subscriber: TBoldSubscriber): Boolean; virtual;

Each time SendQuery is called on a TBoldPublisher, TBoldSubscriber_Answer is be called on each subscriber holding a subscription matching the event. If all Answer calls return True, SendQuery will return True. If any Answer returns False, SendQuery returns False. The process is terminated on the first False reply, so there is no guarantee that Answer will be called for all subscribers.

This function is only called by TBoldPublisher.

Parameters

Originator	The object originating the event, given as parameter to SendQuery.
OriginalEvent	The event send by Originator
RequestedEvent	The requested event given when placing the subscription with AddSubscription or AddSmallSubscription.

CancelAllSubscriptions¶

procedure CancelAllSubscriptions;

This method cancels all the subscribers subscriptions.

CloneSubscriptions¶

procedure CloneSubscriptions(Subscriber: TBoldSubscriber; OldRequestedEvent: TBoldRequestedEvent; NewRequestedEvent: TBoldRequestedEvent);

Destroy¶

destructor Destroy; override;

GetContextString¶

function GetContextString: string; virtual;

Default implementation of property ContextString, returns ''

GetHandlesExtendedEvents¶

function GetHandlesExtendedEvents: Boolean; virtual;

Implements the property HandlesExtendedEvents. The base implementation always returns false, but subclasses may override this.

Receive¶

procedure Receive(Originator: TObject; OriginalEvent: TBoldEvent; RequestedEvent: TBoldRequestedEvent); virtual; abstract;

Receive is an abstract method that must be implemented in each concrete subclass. This procedure is only called by TBoldPublisher.

Parameters

OriginalEvent	the event that triggers the subscription
Originator	the object on which OriginalEvent occurred
RequestedEvent	the event requested when placing the subscription with AddSubscription or AddSmallSubscription

ReceiveExtended¶

procedure ReceiveExtended(Originator: TObject; OriginalEvent: TBoldEvent; RequestedEvent: TBoldRequestedEvent; const Args: array of const); virtual;

This method is similar to Receive, but it also get a set of arguments that were provided by the object who sent the event. Subscribers that implements ReceiveExtended should always override the GetHandlesExtendedEvents otherwise this method will never be called.

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