source: Dev/trunk/src/client/dojo/Stateful.js @ 527

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 names = this._getAttrNames(name),
                        oldValue = this._get(name, names),
                        setter = this[names.s],
                        result;
                if(typeof setter === "function"){
                        // use the explicit setter
                        result = setter.apply(this, Array.prototype.slice.call(arguments, 1));
                }else{
                        // no setter so set attribute directly
                        this[name] = value;
                }
                if(this._watchCallbacks){
                        var self = this;
                        // If setter returned a promise, wait for it to complete, otherwise call watches immediatly
                        when(result, function(){
                                self._watchCallbacks(name, oldValue, value);
                        });
                }
                return this; // dojo/Stateful
        },
        _changeAttrValue: function(name, value){
                // summary:
                //              Internal helper for directly changing an attribute value.
                //
                // name: String
                //              The property to set.
                // value: Mixed
                //              The value to set in the property.
                //
                // description:
                //              Directly change the value of an attribute on an object, bypassing any 
                //              accessor setter.  Also handles the calling of watch and emitting events. 
                //              It is designed to be used by descendent class when there are two values 
                //              of attributes that are linked, but calling .set() is not appropriate.

                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.

                var callbacks = this._watchCallbacks;
                if(!callbacks){
                        var self = this;
                        callbacks = this._watchCallbacks = function(name, oldValue, value, ignoreCatchall){
                                var notify = function(propertyCallbacks){
                                        if(propertyCallbacks){
                                                propertyCallbacks = propertyCallbacks.slice();
                                                for(var i = 0, l = propertyCallbacks.length; i < l; i++){
                                                        propertyCallbacks[i].call(self, name, oldValue, value);
                                                }
                                        }
                                };
                                notify(callbacks['_' + name]);
                                if(!ignoreCatchall){
                                        notify(callbacks["*"]); // the catch-all
                                }
                        }; // we use a function instead of an object so it will be ignored by JSON conversion
                }
                if(!callback && typeof name === "function"){
                        callback = name;
                        name = "*";
                }else{
                        // prepend with dash to prevent name conflicts with function (like "name" property)
                        name = '_' + name;
                }
                var propertyCallbacks = callbacks[name];
                if(typeof propertyCallbacks !== "object"){
                        propertyCallbacks = callbacks[name] = [];
                }
                propertyCallbacks.push(callback);

                // 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
        }

});

});