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坡贞孟
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1 无类继承 JavaScript 面向对象的根基周爱民 / aimingoo aiming@gmail.com

rand = new Person("Rand McKinnon",... https://docs.oracle.

2 rand = new Person("Rand McKinnon",

3 function car(make, model, year) { this.make = make; this.model = model;

4 JavaScript 1.1 prototype based

5 function MyObject() { this.xxx = } MyObject.prototype = new Object(); MyObject.prototype.constructor = MyObject;... obj = new MyObject(); obj.x = 100;

6 Object() prototype.tostring().xxx proto MyObject() prototype.constructor proto obj x: 100 console.log(obj.x); console.log(obj.xxx); console.log(obj.tostring());

7 原型继承类抄写声明 : 类 / 原型 / 对象... 类继承 js1.1 ~ 1.x js2 ECMAScript edition 1~4

8 ECMAScript Ed5 Non-classes based

9 Object.hasOwnProperty(obj,...) Object.defineProperty(obj,...) Object.freeze() Object.XXXX()...

10 obj = Object.create(X, {... })

11 Object.setPrototypeOf(obj, X)

12 X.isPrototypeOf(obj)

13 X.isPrototypeOf(obj) vs. obj instanceof Object

14 1. 对象就是属性包 1 2 所以原型继承就是属性包的链式访问所以可以没有类继承 ( 例例如构造器器和 new) an object is a collection of properties

15 JavaScript 2015 ECMAScript Ed 6 / ES6 该来的总会来的

16 let obj = { name: 'obj', foo() {... } }

17 homeobj = Method[[HomeObject]]; super = Object.getPrototypeOf(homeObj)

18 let obj = { foo() { // 所以这是静态声明初始器赋值 console.log(super.name, this.name); } } Object.setPrototypeOf(obj, {name: 'Super'}); obj.name = 'obj'; obj.foo(); // Super, obj let obj2 = Object.create(obj, {name: 'I am obj2'}); obj2.foo(); // Super, I am obj2

19 let foo = obj.foo; foo(); //???,???

20 Class is appearances

21 class MyClass extends X { constructor() {.. } static foo() {.. } more() {...

22 class MyClass extends X { constructor() { super();.. } static foo() {.. } more() {..... // bind classname and set prototypes MyClass = asclassconstructor(constructor); Object.setPrototypeOf(MyClass, X); Object.setPrototypeOf(MyClass.prototype, X.prototype); = // for static methods sethomeobject(foo, MyClass); // for constructor and instance methods sethomeobject(constructor, MyClass.prototype); sethomeobject(more, MyClass.prototype);

23 class MyClass {} class MyClass extends X {}

24 class MyClass { constructor() { } } // no "super()" class MyClass extends X { constructor(...args) { // default super(...args); } }

25 > class MyClass extends null {} > obj = new MyClass; TypeError: Super constructor null of > Object.setPrototypeOf(MyClass, Object) > typeof(obj = new MyClass) 'object'

26 new X New or create

27 Base() prototype.tostring().xxx function MyObject() {} MyObject.prototype = new Base(); MyObject.prototype.foo =... proto MyObject() prototype.constructor proto obj = new MyObject; obj foo:...

$..... obj2 = new MyClass; Base() constructor { _this = new_instance() setprototypeof(_this, new.target.prototype); // binding <this> or return... } MyClass() constructor { super(); // with new.target...... obj2 is <_this> obj2 obj2 = new MyClass; obj2.$

28 function MyObject() {} MyObject.prototype = new Base(); MyObject.prototype.foo =... obj = new MyObject; class MyClass extends Base { constructor() {... foo() { obj2 = new MyClass; Base() constructor { _this = new_instance() setprototypeof(_this, new.target.prototype); // binding <this> or return... } MyClass() constructor { super(); // with new.target obj2 is <_this> obj2 obj2 = new MyClass; obj2.foo();

29 // success class MyDate extends Date {... // fail MyFunction.prototype = Function; } MyDate.prototype = new Date();... // success class MyFunction extends Function {... }

30 class MyClass extends X; 1 2 父类 X 是可以通过写类的原型来重置的 super 总是通过计算指向 X, 并受上述重置影响 obj = new MyClass; 1 obj 总是由祖先类 (Base) 创建的实例例

31 Atom Meta based

32 X = Object.create(null); Object.setPrototypeOf(X null);

33 function isatom(obj) { let types = {object: true, function: true}; if (types[typeof obj]) { return!(obj instanceof Object); } return false; }

34 arguments namespace // for arguments args = Function('return arguments')(); isatom(args); // true // for namespace import * as namespace from "./exports.mjs"; isatom(namespace); // true

35 atom 原子 meta 元能产生原子的一个过程 Meta - 能产生meta的一个过程称为元类型 MetaClass - 如果所产生的meta是一个类则这个Meta称为元类类型 // 如下代码意味着Atom()是元函数或元构造器器 atom = new Atom();

36 // a meta/atom-constructor, derived from null, it s meta style class meta extends null {...

37 // Atom() for meta system class Atom extends null { constructor() { return Object.create(new.target.prototype); } }

38 // Atom() for meta system class Atom... // Meta class Meta extends null { constructor() { return Object.setPrototypeOf( class extends new.target{}, Atom); } }

39 // Atom() for meta system class Atom... // Meta class Meta... // to atom style void Object.setPrototypeOf(Atom, null); void Object.setPrototypeOf(Meta, null);

40 // Atom() for meta system class Atom... // Meta class Meta... // to atom style... // Meta Classes class MetaClass extends Meta { static isclassof(x) { return x instanceof this x.prototype instanceof this; } }

41 // Atom() for meta system class Atom... // Meta class Meta... // to atom style... // Meta Classes class MetaClass extends Meta {... class MetaObject extends new MetaClass {} x = new MetaObject;

42 > [MetaObject, MetaClass, Meta, Atom, x].foreach(x=>console.log(isatom(x))); true true true true true > typeof x 'object'

43 class Meta class MetaClass class MetaObject extends new MetaClass {} class MetaX extends MetaClass {} Meta (元类型) extends extends class MetaObjectEx extends MetaObject {} obj = new MetaObject; obj2 = new MetaObjectEx; MetaClass (元类) MetaX (派生类) Meta-class instantiation Meta based ECMAScript based MetaObject (实例例类) instanceof is 'true' extends MetaObjectEx obj instanceof is 'true' obj2

44 > Meta.isAtom(null); true > Meta.isAtom(Object.prototype); true

45 > Objext = Meta.from(Object);

46 atom Object.prototype > Objext = Meta.from(Object); > Objext.keys(new Objext); [] Atom Meta MetaClass MetaObject Objext = Object

47 Ox bje t github.com/aimingoo/metameta

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