| Package | mx.binding.utils |
| Class | public class ChangeWatcher |
| Inheritance | ChangeWatcher  Object |
| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
More examples
Hide Inherited Public Properties
Show Inherited Public Properties| Property | Defined By | ||
|---|---|---|---|
 | constructor : Object
A reference to the class object or constructor function for a given object instance. | Object | |
| useWeakReference : Boolean
Determines whether the reference to handler
is strong or weak. | ChangeWatcher | ||
| Method | Defined By | ||
|---|---|---|---|
ChangeWatcher(access:Object, handler:Function, commitOnly:Boolean = false, next:ChangeWatcher = null)
Constructor. | ChangeWatcher | ||
[static]
Lets you determine if the host exposes a data-binding event
on the property. | ChangeWatcher | ||
[static]
Returns all binding events for a bindable property in the host object. | ChangeWatcher | ||
Retrieves the current value of the watched property or property chain,
or null if the host object is null. | ChangeWatcher | ||
|
Indicates whether an object has a specified property defined. | Object | |
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Indicates whether an instance of the Object class is in the prototype chain of the object specified
as the parameter. | Object | |
Returns true if each watcher in the chain is attached
to at least one change event. | ChangeWatcher | ||
|
Indicates whether the specified property exists and is enumerable. | Object | |
Resets this ChangeWatcher instance to use a new host object. | ChangeWatcher | ||
Sets the handler function. | ChangeWatcher | ||
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Sets the availability of a dynamic property for loop operations. | Object | |
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Returns the string representation of this object, formatted according to locale-specific conventions. | Object | |
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Returns the string representation of the specified object. | Object | |
Detaches this ChangeWatcher instance, and its handler function,
from the current host. | ChangeWatcher | ||
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Returns the primitive value of the specified object. | Object | |
watch(host:Object, chain:Object, handler:Function, commitOnly:Boolean = false, useWeakReference:Boolean = false):ChangeWatcher [static]
Creates and starts a ChangeWatcher instance. | ChangeWatcher | ||
useWeakReference | property |
public var useWeakReference:Boolean| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | 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.
The default value is false.
ChangeWatcher | () | Constructor |
public function ChangeWatcher(access:Object, handler:Function, commitOnly:Boolean = false, next:ChangeWatcher = null)| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | 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.
access:Object | |
handler:Function | |
commitOnly:Boolean (default = false) | |
next:ChangeWatcher (default = null) |
canWatch | () | method |
public static function canWatch(host:Object, name:String, commitOnly:Boolean = false):Boolean| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | 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.
Parameters
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)true if the handler
should be called only on committing change events.
See the watch() method for more information.
|
Boolean — true if host exposes
any change events on name.
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getEvents | () | method |
public static function getEvents(host:Object, name:String, commitOnly:Boolean = false):Object| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | Flash Player 9, AIR 1.1 |
Returns all binding events for a bindable property in the host object.
Parameters
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) |
Object — Object of the form { eventName: isCommitting, ... }
containing all change events for the property.
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getValue | () | method |
public function getValue():Object| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | 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
ReturnsObject — The current value of the watched property or property chain.
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isWatching | () | method |
public function isWatching():Boolean| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | 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.
Boolean — true if each watcher in the chain is attached
to at least one change event.
|
reset | () | method |
public function reset(newHost:Object):void| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | 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.
Parameters
newHost:Object — The new host of the property.
See the watch() method for more information.
|
setHandler | () | method |
unwatch | () | method |
public function unwatch():void| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | 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 | () | method |
public static function watch(host:Object, chain:Object, handler:Function, commitOnly:Boolean = false, useWeakReference:Boolean = false):ChangeWatcher| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 3 |
| Runtime Versions: | 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).
Parameters
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:
Note: The property or properties named in the | |
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
| |
commitOnly:Boolean (default = false)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)handler is strong or weak. A strong
reference (the default) prevents handler from being
garbage-collected. A weak reference does not.
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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.
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Mon Apr 10 2017, 12:28 PM -07:00