On Friday, 2011-06-24 at 21:13 , Axel Rauschmayer wrote: > I’m trying to understand all the implications of Irakli’s code. > > https://gist.github.com/d33befccbe1e0ed492d5 > > Object.prototype.new = function new() { > return new this.constructor(); > }; > Object.prototype.extend = function extend(properties) { > var constructor = new Function(), descriptor = {}; > properties = properties || {}; > Object.getOwnPropertyNames(properties).forEach(function(name) { > descriptor[name] = Object.getOwnPropertyDescriptor(properties, name); > }); > descriptor.constructor = { value: constructor }; > return Object.freeze(constructor.prototype = Object.create(this, > descriptor)); > }; > > Object.new = function new() { > return Object.prototype.new(); > }; > Object.extend = function extend(properties) { > return Object.prototype.extend(properties); > }; > > Questions: > > 1. Do "new" and "extend" really work properly on any built-in other than > Object? > - E.g., I would expect String.extend() to lead to the invocation of > Object.prototype.extend() which assumes "this" to be a prototype, but it is a > constructor. > - This could be fixed by checking whether "this" is a function and then > acting accordingly. Or by setting up a constructor/class method "extend" for > each built-in. I have not tried or thought much about other build-ins as showing idea was a main point. Yeah I was thinking that similar methods could be created per build-ins if necessary. > 2. I don’t like that new() methods have to keep the result of super.new() and > return it. I would prefer something like the code below, which enables a > constructor behavior like in Allen’s example. > I personally think that whole prototype, constructor and new keyword relationships add a lot of complexity to a language, and since this was fitting discussion nicely I though I'd share idea how this can be evolved to something more straight forward, that fits language much more IMO. I like new as a method because code is becomes simple and obvious. > 3. Are my changes really an improvement or do they impede proper interaction > with built-ins, somehow? > > ===== Library code ===== > > // Optional, possibly faster: split the method below into > Object.prototype.new and Function.prototype.new (the latter overriding the > former) > Object.prototype.new = function new() { > if (this instanceof Function) { > return new this(); > } else { > return new this.constructor(); > } > }; > // Performance is less of an issue for this method > Object.prototype.extend = function extend(properties) { > var superProto; > if (this instanceof Function) { > superProto = this.prototype; > } else { > superProto = this; > } > var descriptor = {}; > properties = properties || {}; > Object.getOwnPropertyNames(properties).forEach(function(name) { > descriptor[name] = Object.getOwnPropertyDescriptor(properties, name); > }); > var thisProto = Object.create(superProto, descriptor); > if (thisProto.constructor) { > thisProto.constructor.prototype = thisProto; > } > thisProto.__super__ = superProto; > return thisProto; > }; > > // Optional: split the method below into Object.prototype.hasInstance and > Function.prototype.hasInstance > Object.prototype.hasInstance = function extend(instance) { > if (this instanceof Function) { > return instance instanceof this; > } else { > return this.isPrototypeOf(instance); > } > }; In my library I just use Foo.isPrototypeOf(bar); https://github.com/Gozala/selfish > > /**** Not necessary, any more (Object instanceof Object) > Object.new = function new() { > return Object.prototype.new(); > }; > Object.extend = function extend(properties) { > return Object.prototype.extend(properties); > }; > ****/ > > ===== Using the library ===== > > const SkinnedMesh = THREE.Mesh.extend({ > constructor: function SkinnedMesh(geometry, materials) { > SkinnedMesh.__super__.constructor.apply(this, arguments); > // initialize instance properties > this.identityMatrix = THREE.Matrix4.new(); > this.bones = []; > this.boneMatrices = []; > }, > update: function(camera) { > ... > // call base version of same method > SkinnedMesh.__super__.update.call(this); > } > }); > _______________________________________________ > es-discuss mailing list > [email protected] (mailto:[email protected]) > https://mail.mozilla.org/listinfo/es-discuss
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