ChangeWatcher

패키지	mx.binding.utils
클래스	public class ChangeWatcher
상속	ChangeWatcher Object

언어 버전:

ActionScript 3.0

제품 버전:

Flex 3

런타임 버전:

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.

기타 예제

Defining binding watchers

공용 속성

상속되는 공용 속성 숨기기

상속되는 공용 속성 표시

	속성		정의 주체
		constructor : Object 지정된 객체 인스턴스의 클래스 객체 또는 생성자 함수에 대한 참조입니다.	Object
		useWeakReference : Boolean Determines whether the reference to handler is strong or weak.	ChangeWatcher

공용 메서드

상속되는 공용 메서드 숨기기

상속되는 공용 메서드 표시

	메서드		정의 주체
		ChangeWatcher(access:Object, handler:Function, commitOnly:Boolean = false, next:ChangeWatcher = null) Constructor.	ChangeWatcher
		canWatch(host:Object, name:String, commitOnly:Boolean = false):Boolean [정적] Lets you determine if the host exposes a data-binding event on the property.	ChangeWatcher
		getEvents(host:Object, name:String, commitOnly:Boolean = false):Object [정적] 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 지정된 속성이 객체에 정의되어 있는지 여부를 나타냅니다.	Object
		isPrototypeOf(theClass:Object):Boolean Object 클래스의 인스턴스가 매개 변수로 지정된 객체의 프로토타입 체인에 있는지 여부를 나타냅니다.	Object
		isWatching():Boolean Returns true if each watcher in the chain is attached to at least one change event.	ChangeWatcher
		propertyIsEnumerable(name:String):Boolean 지정된 속성이 존재하고 열거 가능한지 여부를 나타냅니다.	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 루프 작업에서 동적 속성을 사용할 수 있는지 여부를 설정합니다.	Object
		toLocaleString():String 로캘별 규칙에 따라 서식이 지정된 이 객체의 문자열 표현을 반환합니다.	Object
		toString():String 지정된 객체의 문자열 표현을 반환합니다.	Object
		unwatch():void Detaches this ChangeWatcher instance, and its handler function, from the current host.	ChangeWatcher
		valueOf():Object 지정된 객체의 프리미티브 값을 반환합니다.	Object
		watch(host:Object, chain:Object, handler:Function, commitOnly:Boolean = false, useWeakReference:Boolean = false):ChangeWatcher [정적] Creates and starts a ChangeWatcher instance.	ChangeWatcher

속성 세부 정보

useWeakReference

속성

public var useWeakReference:Boolean

언어 버전:

ActionScript 3.0

제품 버전:

Flex 3

런타임 버전:

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.

기본값: false.

생성자 세부 정보

()

생성자

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

언어 버전:

ActionScript 3.0

제품 버전:

Flex 3

런타임 버전:

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.

매개 변수

	`access:Object`

	`handler:Function`

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

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

메서드 세부 정보

canWatch

()

메서드

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

언어 버전:

ActionScript 3.0

제품 버전:

Flex 3

런타임 버전:

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.

매개 변수

	`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.

반환값

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

getEvents

()

메서드

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

언어 버전:

ActionScript 3.0

제품 버전:

Flex 3

런타임 버전:

Flash Player 9, AIR 1.1

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

매개 변수

	`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.

반환값

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

getValue

()

메서드

public function getValue():Object

언어 버전:

ActionScript 3.0

제품 버전:

Flex 3

런타임 버전:

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

반환값

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

isWatching

()

메서드

public function isWatching():Boolean

언어 버전:

ActionScript 3.0

제품 버전:

Flex 3

런타임 버전:

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.

반환값

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

reset

()

메서드

public function reset(newHost:Object):void

언어 버전:

ActionScript 3.0

제품 버전:

Flex 3

런타임 버전:

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.

매개 변수

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

setHandler

()

메서드

public function setHandler(handler:Function):void

언어 버전:

ActionScript 3.0

제품 버전:

Flex 3

런타임 버전:

Flash Player 9, AIR 1.1

Sets the handler function.

매개 변수

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

unwatch

()

메서드

public function unwatch():void

언어 버전:

ActionScript 3.0

제품 버전:

Flex 3

런타임 버전:

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

()

메서드

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

언어 버전:

ActionScript 3.0

제품 버전:

Flex 3

런타임 버전:

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).

매개 변수

	`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.

반환값

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.

ChangeWatcher - AS3 Flex

클래스 x

useWeakReference

ChangeWatcher

canWatch

getEvents

getValue

isWatching

reset

setHandler

unwatch

watch