214 lines
6.8 KiB
JavaScript
214 lines
6.8 KiB
JavaScript
define("dojo/Stateful", ["./_base/declare", "./_base/lang", "./_base/array", "dojo/when"], function(declare, lang, array, when){
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// module:
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// dojo/Stateful
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return declare("dojo.Stateful", null, {
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// summary:
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// Base class for objects that provide named properties with optional getter/setter
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// control and the ability to watch for property changes
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//
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// The class also provides the functionality to auto-magically manage getters
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// and setters for object attributes/properties.
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//
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// Getters and Setters should follow the format of _xxxGetter or _xxxSetter where
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// the xxx is a name of the attribute to handle. So an attribute of "foo"
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// would have a custom getter of _fooGetter and a custom setter of _fooSetter.
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//
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// example:
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// | var obj = new dojo.Stateful();
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// | obj.watch("foo", function(){
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// | console.log("foo changed to " + this.get("foo"));
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// | });
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// | obj.set("foo","bar");
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// _attrPairNames: Hash
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// Used across all instances a hash to cache attribute names and their getter
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// and setter names.
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_attrPairNames: {},
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_getAttrNames: function(name){
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// summary:
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// Helper function for get() and set().
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// Caches attribute name values so we don't do the string ops every time.
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// tags:
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// private
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var apn = this._attrPairNames;
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if(apn[name]){ return apn[name]; }
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return (apn[name] = {
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s: "_" + name + "Setter",
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g: "_" + name + "Getter"
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});
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},
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postscript: function(/*Object?*/ params){
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// Automatic setting of params during construction
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if (params){ this.set(params); }
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},
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_get: function(name, names){
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// summary:
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// Private function that does a get based off a hash of names
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// names:
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// Hash of names of custom attributes
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return typeof this[names.g] === "function" ? this[names.g]() : this[name];
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},
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get: function(/*String*/name){
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// summary:
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// Get a property on a Stateful instance.
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// name:
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// The property to get.
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// returns:
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// The property value on this Stateful instance.
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// description:
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// Get a named property on a Stateful object. The property may
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// potentially be retrieved via a getter method in subclasses. In the base class
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// this just retrieves the object's property.
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// For example:
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// | stateful = new dojo.Stateful({foo: 3});
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// | stateful.get("foo") // returns 3
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// | stateful.foo // returns 3
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return this._get(name, this._getAttrNames(name)); //Any
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},
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set: function(/*String*/name, /*Object*/value){
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// summary:
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// Set a property on a Stateful instance
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// name:
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// The property to set.
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// value:
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// The value to set in the property.
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// returns:
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// The function returns this dojo.Stateful instance.
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// description:
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// Sets named properties on a stateful object and notifies any watchers of
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// the property. A programmatic setter may be defined in subclasses.
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// For example:
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// | stateful = new dojo.Stateful();
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// | stateful.watch(function(name, oldValue, value){
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// | // this will be called on the set below
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// | }
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// | stateful.set(foo, 5);
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//
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// set() may also be called with a hash of name/value pairs, ex:
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// | myObj.set({
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// | foo: "Howdy",
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// | bar: 3
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// | })
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// This is equivalent to calling set(foo, "Howdy") and set(bar, 3)
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// If an object is used, iterate through object
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if(typeof name === "object"){
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for(var x in name){
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if(name.hasOwnProperty(x) && x !="_watchCallbacks"){
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this.set(x, name[x]);
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}
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}
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return this;
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}
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var names = this._getAttrNames(name),
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oldValue = this._get(name, names),
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setter = this[names.s],
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result;
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if(typeof setter === "function"){
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// use the explicit setter
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result = setter.apply(this, Array.prototype.slice.call(arguments, 1));
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}else{
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// no setter so set attribute directly
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this[name] = value;
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}
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if(this._watchCallbacks){
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var self = this;
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// If setter returned a promise, wait for it to complete, otherwise call watches immediatly
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when(result, function(){
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self._watchCallbacks(name, oldValue, value);
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});
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}
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return this; // dojo/Stateful
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},
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_changeAttrValue: function(name, value){
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// summary:
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// Internal helper for directly changing an attribute value.
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//
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// name: String
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// The property to set.
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// value: Mixed
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// The value to set in the property.
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//
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// description:
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// Directly change the value of an attribute on an object, bypassing any
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// accessor setter. Also handles the calling of watch and emitting events.
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// It is designed to be used by descendent class when there are two values
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// of attributes that are linked, but calling .set() is not appropriate.
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var oldValue = this.get(name);
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this[name] = value;
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if(this._watchCallbacks){
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this._watchCallbacks(name, oldValue, value);
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}
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return this; // dojo/Stateful
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},
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watch: function(/*String?*/name, /*Function*/callback){
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// summary:
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// Watches a property for changes
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// name:
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// Indicates the property to watch. This is optional (the callback may be the
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// only parameter), and if omitted, all the properties will be watched
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// returns:
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// An object handle for the watch. The unwatch method of this object
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// can be used to discontinue watching this property:
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// | var watchHandle = obj.watch("foo", callback);
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// | watchHandle.unwatch(); // callback won't be called now
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// callback:
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// The function to execute when the property changes. This will be called after
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// the property has been changed. The callback will be called with the |this|
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// set to the instance, the first argument as the name of the property, the
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// second argument as the old value and the third argument as the new value.
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var callbacks = this._watchCallbacks;
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if(!callbacks){
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var self = this;
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callbacks = this._watchCallbacks = function(name, oldValue, value, ignoreCatchall){
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var notify = function(propertyCallbacks){
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if(propertyCallbacks){
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propertyCallbacks = propertyCallbacks.slice();
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for(var i = 0, l = propertyCallbacks.length; i < l; i++){
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propertyCallbacks[i].call(self, name, oldValue, value);
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}
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}
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};
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notify(callbacks['_' + name]);
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if(!ignoreCatchall){
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notify(callbacks["*"]); // the catch-all
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}
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}; // we use a function instead of an object so it will be ignored by JSON conversion
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}
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if(!callback && typeof name === "function"){
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callback = name;
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name = "*";
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}else{
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// prepend with dash to prevent name conflicts with function (like "name" property)
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name = '_' + name;
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}
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var propertyCallbacks = callbacks[name];
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if(typeof propertyCallbacks !== "object"){
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propertyCallbacks = callbacks[name] = [];
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}
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propertyCallbacks.push(callback);
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// TODO: Remove unwatch in 2.0
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var handle = {};
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handle.unwatch = handle.remove = function(){
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var index = array.indexOf(propertyCallbacks, callback);
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if(index > -1){
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propertyCallbacks.splice(index, 1);
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}
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};
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return handle; //Object
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}
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});
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});
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