Eventi

Definire e attivare gli eventi; creare ascoltatori che rispondano agli eventi

Gli eventi sono avvisi trasmessi quando si verifica un cambiamento o un'azione che coinvolge un oggetto. Gli ascoltatori definiscono le funzioni che vengono eseguite quando si verificano eventi specifici. Le classi possono definire e attivare gli eventi. MATLAB^® può attivare eventi predefiniti quando il codice accede alle proprietà degli oggetti.

Funzioni

`events`	Event names
`notify`	Notify listeners that event is occurring
`addlistener`	Create event listener bound to event source
`listener`	Create event listener without binding to event source
`event.hasListener`	Determine if listeners exist for event

Classi

`event.EventData`	Base class for event data
`event.ClassInstanceEvent`	Event data for `InstanceCreated` and `InstanceDestroyed` events
`event.listener`	Class defining listener objects
`event.PropertyEvent`	Data for property events
`event.proplistener`	Define listener object for property events

Argomenti

Eventi e ascoltatori

Overview Events and Listeners
Use events and listeners to send and respond to messages.
Event and Listener Concepts
Events broadcast notifications to all registered listener and pass event-specific data to listener callback functions.
Events and Listeners Syntax
These code examples show how to define events and listeners.
Event Access List
Specify a list of classes that can be notified of a specific event.
Event Attributes
Control access to events by setting event attributes.

Implementazione degli ascoltatori

Listener Callback Syntax
Specify listener callbacks using function handles.
Callback Execution
Errors in listener callbacks do not prevent execution of other listeners. However, the order of listener execution is not defined.
Listener Lifecycle
MATLAB manages the lifecycle of listeners. For greater control of listener lifecycle, construct listener objects using the listener method instead of addlistener.
Determine If Event Has Listeners
You can determine if there are listeners defined for a specific event and event source.

Ascoltatori della proprietà

Listen for Changes to Property Values
MATLAB defines pre and post set and get events for all properties.
Assignment When Property Value Is Unchanged
Prevent the triggering of property events when values do not change using the property AbortSet attribute.

Esempi di eventi e di ascoltatori

Define Custom Event Data
Redefine the event data that MATLAB passes to listeners when an event is triggered.
Observe Changes to Property Values
Listeners can respond to changes in the value of properties using predefined property events.
Implement Property Set Listener
Listeners can respond to changes in property values before or after MATLAB assigns the value.
Techniques for Using Events and Listeners
This example shows how to enable and disable listener execution using context menus.
Restore Listeners
You can restore property listeners from the loadobj method.