Plato - dojo/Stateful.js

define(["./_base/declare", "./_base/lang", "./_base/array", "./when"], function(declare, lang, array, when){
	// module:
	//		dojo/Stateful

return declare("dojo.Stateful", null, {
	// summary:
	//		Base class for objects that provide named properties with optional getter/setter
	//		control and the ability to watch for property changes
	//
	//		The class also provides the functionality to auto-magically manage getters
	//		and setters for object attributes/properties.
	//		
	//		Getters and Setters should follow the format of _xxxGetter or _xxxSetter where 
	//		the xxx is a name of the attribute to handle.  So an attribute of "foo" 
	//		would have a custom getter of _fooGetter and a custom setter of _fooSetter.
	//
	// example:
	//	|	require(["dojo/Stateful", function(Stateful) {
	//	|		var obj = new Stateful();
	//	|		obj.watch("foo", function(){
	//	|			console.log("foo changed to " + this.get("foo"));
	//	|		});
	//	|		obj.set("foo","bar");
	//	|	});

// _attrPairNames: Hash
	//		Used across all instances a hash to cache attribute names and their getter 
	//		and setter names.
	_attrPairNames: {},

_getAttrNames: function(name){
		// summary:
		//		Helper function for get() and set().
		//		Caches attribute name values so we don't do the string ops every time.
		// tags:
		//		private

var apn = this._attrPairNames;
		if(apn[name]){ return apn[name]; }
		return (apn[name] = {
			s: "_" + name + "Setter",
			g: "_" + name + "Getter"
		});
	},

postscript: function(/*Object?*/ params){
		// Automatic setting of params during construction
		if (params){ this.set(params); }
	},

_get: function(name, names){
		// summary:
		//		Private function that does a get based off a hash of names
		// names:
		//		Hash of names of custom attributes
		return typeof this[names.g] === "function" ? this[names.g]() : this[name];
	},
	get: function(/*String*/name){
		// summary:
		//		Get a property on a Stateful instance.
		// name:
		//		The property to get.
		// returns:
		//		The property value on this Stateful instance.
		// description:
		//		Get a named property on a Stateful object. The property may
		//		potentially be retrieved via a getter method in subclasses. In the base class
		//		this just retrieves the object's property.
		// example:
		//	|	require(["dojo/Stateful", function(Stateful) {
		//	|		var stateful = new Stateful({foo: 3});
		//	|		stateful.get("foo") // returns 3
		//	|		stateful.foo // returns 3
		//	|	});

return this._get(name, this._getAttrNames(name)); //Any
	},
	set: function(/*String*/name, /*Object*/value){
		// summary:
		//		Set a property on a Stateful instance
		// name:
		//		The property to set.
		// value:
		//		The value to set in the property.
		// returns:
		//		The function returns this dojo.Stateful instance.
		// description:
		//		Sets named properties on a stateful object and notifies any watchers of
		//		the property. A programmatic setter may be defined in subclasses.
		// example:
		//	|	require(["dojo/Stateful", function(Stateful) {
		//	|		var stateful = new Stateful();
		//	|		stateful.watch(function(name, oldValue, value){
		//	|			// this will be called on the set below
		//	|		}
		//	|		stateful.set(foo, 5);
		//	set() may also be called with a hash of name/value pairs, ex:
		//	|		stateful.set({
		//	|			foo: "Howdy",
		//	|			bar: 3
		//	|		});
		//	|	});
		//	This is equivalent to calling set(foo, "Howdy") and set(bar, 3)

// If an object is used, iterate through object
		if(typeof name === "object"){
			for(var x in name){
				if(name.hasOwnProperty(x) && x !="_watchCallbacks"){
					this.set(x, name[x]);
				}
			}
			return this;
		}

var oldValue = this.get(name);
		this[name] = value;
		if(this._watchCallbacks){
			this._watchCallbacks(name, oldValue, value);
		}
		return this; // dojo/Stateful
	},
	watch: function(/*String?*/name, /*Function*/callback){
		// summary:
		//		Watches a property for changes
		// name:
		//		Indicates the property to watch. This is optional (the callback may be the
		//		only parameter), and if omitted, all the properties will be watched
		// returns:
		//		An object handle for the watch. The unwatch method of this object
		//		can be used to discontinue watching this property:
		//		|	var watchHandle = obj.watch("foo", callback);
		//		|	watchHandle.unwatch(); // callback won't be called now
		// callback:
		//		The function to execute when the property changes. This will be called after
		//		the property has been changed. The callback will be called with the |this|
		//		set to the instance, the first argument as the name of the property, the
		//		second argument as the old value and the third argument as the new value.

// TODO: Remove unwatch in 2.0
		var handle = {};
		handle.unwatch = handle.remove = function(){
			var index = array.indexOf(propertyCallbacks, callback);
			if(index > -1){
				propertyCallbacks.splice(index, 1);
			}
		};
		return handle; //Object
	}

});

dojo/Stateful.js

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