ChangeWatcher

Pakiet	mx.binding.utils
Klasa	public class ChangeWatcher
Dziedziczenie	ChangeWatcher Object

Wersja języka:

ActionScript 3.0

Wersja produktu:

Flex 3

Wersje środowiska wykonawczego:

Flash Player 9, AIR 1.1

The ChangeWatcher class defines utility methods that you can use with bindable Flex properties. These methods let you define an event handler that is executed whenever a bindable property is updated.

Właściwości publiczne

Ukryj dziedziczone właściwości publiczne

Pokaż dziedziczone właściwości publiczne

	Właściwość		Zdefiniowane przez
		constructor : Object Odwołanie do obiektu klasy lub funkcji konstruktora, dotyczące danej instancji obiektu.	Object
		useWeakReference : Boolean Determines whether the reference to handler is strong or weak.	ChangeWatcher

Metody publiczne

Ukryj dziedziczone metody publiczne

Pokaż dziedziczone metody publiczne

	Metoda		Zdefiniowane przez
		ChangeWatcher(access:Object, handler:Function, commitOnly:Boolean = false, next:ChangeWatcher = null) Constructor.	ChangeWatcher
		canWatch(host:Object, name:String, commitOnly:Boolean = false):Boolean [statyczny] Lets you determine if the host exposes a data-binding event on the property.	ChangeWatcher
		getEvents(host:Object, name:String, commitOnly:Boolean = false):Object [statyczny] Returns all binding events for a bindable property in the host object.	ChangeWatcher
		getValue():Object Retrieves the current value of the watched property or property chain, or null if the host object is null.	ChangeWatcher
		hasOwnProperty(name:String):Boolean Wskazuje, czy dla obiektu zdefiniowano określoną właściwość.	Object
		isPrototypeOf(theClass:Object):Boolean Wskazuje, czy instancja klasy Object należy do łańcucha prototypów obiektu określonego jako parametr.	Object
		isWatching():Boolean Returns true if each watcher in the chain is attached to at least one change event.	ChangeWatcher
		propertyIsEnumerable(name:String):Boolean Wskazuje, czy określona właściwość istnieje i jest przeliczalna.	Object
		reset(newHost:Object):void Resets this ChangeWatcher instance to use a new host object.	ChangeWatcher
		setHandler(handler:Function):void Sets the handler function.	ChangeWatcher
		setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void Ustawia dostępność właściwości dynamicznej używanej w pętlach.	Object
		toLocaleString():String Zwraca ciąg reprezentujący obiekt — sformatowany zgodnie z konwencjami właściwymi dla ustawień regionalnych.	Object
		toString():String Zwraca ciąg reprezentujący określony obiekt.	Object
		unwatch():void Detaches this ChangeWatcher instance, and its handler function, from the current host.	ChangeWatcher
		valueOf():Object Zwraca pierwotną wartość dla określonego obiektu.	Object
		watch(host:Object, chain:Object, handler:Function, commitOnly:Boolean = false, useWeakReference:Boolean = false):ChangeWatcher [statyczny] Creates and starts a ChangeWatcher instance.	ChangeWatcher

Szczegół właściwości

useWeakReference

właściwość

public var useWeakReference:Boolean

Wersja języka:

ActionScript 3.0

Wersja produktu:

Flex 3

Wersje środowiska wykonawczego:

Flash Player 9, AIR 1.1

Determines whether the reference to handler is strong or weak. A strong reference (the default) prevents handler from being garbage-collected. A weak reference does not.

Wartością domyślną jest false.

Konstruktor Szczegół

()

Konstruktor

public function ChangeWatcher(access:Object, handler:Function, commitOnly:Boolean = false, next:ChangeWatcher = null)

Wersja języka:

ActionScript 3.0

Wersja produktu:

Flex 3

Wersje środowiska wykonawczego:

Flash Player 9, AIR 1.1

Constructor. Not for public use. This method is called only from the watch() method. See the watch() method for parameter usage.

Parametry

	`access:Object`

	`handler:Function`

	`commitOnly:Boolean` (default = `false`)

	`next:ChangeWatcher` (default = `null`)

Szczegół metody

canWatch

()

metoda

public static function canWatch(host:Object, name:String, commitOnly:Boolean = false):Boolean

Wersja języka:

ActionScript 3.0

Wersja produktu:

Flex 3

Wersje środowiska wykonawczego:

Flash Player 9, AIR 1.1

Lets you determine if the host exposes a data-binding event on the property.

NOTE: Property chains are not supported by the canWatch() method. They are supported by the watch() method.

Parametry

	`host:Object` — The host of the property. See the `watch()` method for more information.

	`name:String` — The name of the property. See the `watch()` method for more information.

	`commitOnly:Boolean` (default = `false`) — Set to `true` if the handler should be called only on committing change events. See the `watch()` method for more information.

Zwraca

Boolean — true if host exposes any change events on name.

getEvents

()

metoda

public static function getEvents(host:Object, name:String, commitOnly:Boolean = false):Object

Wersja języka:

ActionScript 3.0

Wersja produktu:

Flex 3

Wersje środowiska wykonawczego:

Flash Player 9, AIR 1.1

Returns all binding events for a bindable property in the host object.

Parametry

	`host:Object` — The host of the property. See the `watch()` method for more information.

	`name:String` — The name of the property, or property chain. See the `watch()` method for more information.

	`commitOnly:Boolean` (default = `false`) — Controls inclusion of non-committing change events in the returned value.

Zwraca

Object — Object of the form { eventName: isCommitting, ... } containing all change events for the property.

getValue

()

metoda

public function getValue():Object

Wersja języka:

ActionScript 3.0

Wersja produktu:

Flex 3

Wersje środowiska wykonawczego:

Flash Player 9, AIR 1.1

Retrieves the current value of the watched property or property chain, or null if the host object is null. For example:

      watch(obj, ["a","b","c"], ...).getValue() === obj.a.b.c

Zwraca

Object — The current value of the watched property or property chain.

isWatching

()

metoda

public function isWatching():Boolean

Wersja języka:

ActionScript 3.0

Wersja produktu:

Flex 3

Wersje środowiska wykonawczego:

Flash Player 9, AIR 1.1

Returns true if each watcher in the chain is attached to at least one change event. Note that the isWatching() method varies with host, since different hosts may expose different change events for the watcher's chosen property.

Zwraca

Boolean — true if each watcher in the chain is attached to at least one change event.

reset

()

metoda

public function reset(newHost:Object):void

Wersja języka:

ActionScript 3.0

Wersja produktu:

Flex 3

Wersje środowiska wykonawczego:

Flash Player 9, AIR 1.1

Resets this ChangeWatcher instance to use a new host object. You can call this method to reuse a watcher instance on a different host.

Parametry

newHost:Object — The new host of the property. See the watch() method for more information.

setHandler

()

metoda

public function setHandler(handler:Function):void

Wersja języka:

ActionScript 3.0

Wersja produktu:

Flex 3

Wersje środowiska wykonawczego:

Flash Player 9, AIR 1.1

Sets the handler function.

Parametry

handler:Function — The handler function. This argument must not be null.

unwatch

()

metoda

public function unwatch():void

Wersja języka:

ActionScript 3.0

Wersja produktu:

Flex 3

Wersje środowiska wykonawczego:

Flash Player 9, AIR 1.1

Detaches this ChangeWatcher instance, and its handler function, from the current host. You can use the reset() method to reattach the ChangeWatcher instance, or watch the same property or chain on a different host object.

watch

()

metoda

 public static function watch(host:Object, chain:Object, handler:Function, commitOnly:Boolean = false, useWeakReference:Boolean = false):ChangeWatcher

Wersja języka:

ActionScript 3.0

Wersja produktu:

Flex 3

Wersje środowiska wykonawczego:

Flash Player 9, AIR 1.1

Creates and starts a ChangeWatcher instance. A single ChangeWatcher instance can watch one property, or a property chain. A property chain is a sequence of properties accessible from a host object. For example, the expression obj.a.b.c contains the property chain (a, b, c).

Parametry

	`host:Object` — The object that hosts the property or property chain to be watched. You can use the use the `reset()` method to change the value of the `host` argument after creating the ChangeWatcher instance. The `host` maintains a list of `handlers` to invoke when `prop` changes.

	`chain:Object` — A value specifying the property or chain to be watched. Legal values are: A String containing the name of a public bindable property of the host object. An Object in the form: `{ name: property name, getter: function(host) { return host[name] } }`. The Object contains the name of a public bindable property, and a function which serves as a getter for that property. A non-empty Array containing any combination of the first two options. This represents a chain of bindable properties accessible from the host. For example, to watch the property `host.a.b.c`, call the method as: `watch(host, ["a","b","c"], ...)`. Note: The property or properties named in the `chain` argument must be public, because the `describeType()` method suppresses all information about non-public properties, including the bindability metadata that ChangeWatcher scans to find the change events that are exposed for a given property. However, the getter function supplied when using the `{ name, getter }` argument form described above can be used to associate an arbitrary computed value with the named (public) property.

	`handler:Function` — An event handler function called when the value of the watched property (or any property in a watched chain) is modified. The modification is signaled when any host object in the watcher chain dispatches the event that has been specified in that host object's `[Bindable]` metadata tag for the corresponding watched property. The default event is named `propertyChange`. The event object dispatched by the bindable property is passed to this handler function without modification. By default, Flex dispatches an event object of type PropertyChangeEvent. However, you can define your own event type when you use the `[Bindable]` metadata tag to define a bindable property.

	`commitOnly:Boolean` (default = `false`) — Set to `true` if the handler should be called only on committing change events; set to `false` if the handler should be called on both committing and non-committing change events. Note: the presence of non-committing change events for a property is indicated by the `[NonCommittingChangeEvent(<event-name>)]` metadata tag. Typically these tags are used to indicate fine-grained value changes, such as modifications in a text field prior to confirmation.

	`useWeakReference:Boolean` (default = `false`) — (default = false) Determines whether the reference to `handler` is strong or weak. A strong reference (the default) prevents `handler` from being garbage-collected. A weak reference does not.

Zwraca

ChangeWatcher — The ChangeWatcher instance, if at least one property name has been specified to the chain argument; null otherwise. Note that the returned watcher is not guaranteed to have successfully discovered and attached itself to change events, since none may have been exposed on the given property or chain by the host. You can use the isWatching() method to determine the watcher's state.

Powiązane elementy interfejsu API

mx.events.PropertyChangeEvent

Informacje prawne | Zasady prywatności online

ChangeWatcher - AS3 Flex

Klasy x

useWeakReference

ChangeWatcher

canWatch

getEvents

getValue

isWatching

reset

setHandler

unwatch

watch