var cache = {};
// 通過(guò)解析Function.prototype.toString()取得參數(shù)名
function getParamNames(func) {
 var paramNames = func.toString().match(/^function\s*[^\(]*\(\s*([^\)]*)\)/m)[1];
 paramNames = paramNames.replace(/ /g, '');
 paramNames = paramNames.split(',');
 return paramNames;
}
var injector = {
 // 將func作用域中的this關(guān)鍵字綁定到bind對(duì)象上，bind對(duì)象可以為空
 resolve: function (func, bind) {
  // 取得參數(shù)名
  var paramNames = getParamNames(func);
  var params = [];
  for (var i = 0; i < paramNames.length; i++) {
   // 通過(guò)參數(shù)名在cache中取出相應(yīng)的依賴(lài)
   params.push(cache[paramNames[i]]);
  }
  // 注入依賴(lài)并執(zhí)行函數(shù)
  func.apply(bind, params);
 }
};
 
function Notebook() {}
Notebook.prototype.printName = function () {
 console.log('this is a notebook');
};
 
function Pencil() {}
Pencil.prototype.printName = function () {
 console.log('this is a pencil');
};
 
function Student() {}
Student.prototype.write = function (notebook, pencil) {
 if (!notebook || !pencil) {
  throw new Error('Dependencies not provided!');
 }
 console.log('writing...');
};
// 提供notebook依賴(lài)
cache['notebook'] = new Notebook();
// 提供pencil依賴(lài)
cache['pencil'] = new Pencil();
var student = new Student();
injector.resolve(student.write, student); // writing...

function Injector() {
 this._cache = {};
}
 
Injector.prototype.put = function (name, obj) {
 this._cache[name] = obj;
};
 
Injector.prototype.getParamNames = function (func) {
 var paramNames = func.toString().match(/^function\s*[^\(]*\(\s*([^\)]*)\)/m)[1];
 paramNames = paramNames.replace(/ /g, '');
 paramNames = paramNames.split(',');
 return paramNames;
};
 
Injector.prototype.resolve = function (func, bind) {
 var self = this;
 var paramNames = self.getParamNames(func);
 var params = paramNames.map(function (name) {
  return self._cache[name];
 });
 func.apply(bind, params);
};
 
var injector = new Injector();
 
var student = new Student();
injector.put('notebook', new Notebook());
injector.put('pencil', new Pencil())
injector.resolve(student.write, student); // writing...
比如現(xiàn)在要執(zhí)行Student類(lèi)上的另一個(gè)方法function draw(notebook, pencil, eraser)，因?yàn)閕njector的cache中已經(jīng)有了notebook和pencil對(duì)象，我們只需要將額外的eraser也存放到cache中：
function Eraser() {}
Eraser.prototype.printName = function () {
 console.log('this is an eraser');
};
 
// 為Student增加draw方法
Student.prototype.draw = function (notebook, pencil, eraser) {
 if (!notebook || !pencil || !eraser) {
  throw new Error('Dependencies not provided!');
 }
 console.log('drawing...');
};
 
injector.put('eraser', new Eraser());
injector.resolve(student.draw, student);

Student.prototype.write.depends = ['notebook', 'pencil'];
Student.prototype.draw.depends = ['notebook', 'pencil', 'eraser'];
Injector.prototype.resolve = function (func, bind) {
 var self = this;
 // 首先檢查func上是否有depends屬性，如果沒(méi)有，再用正則表達(dá)式解析
 func.depends = func.depends || self.getParamNames(func);
 var params = func.depends.map(function (name) {
  return self._cache[name];
 });
 func.apply(bind, params);
};
var student = new Student();
injector.resolve(student.write, student); // writing...
injector.resolve(student.draw, student); // draw...
 

class Pencil {
 public printName() {
  console.log('this is a pencil');
 }
}
 
class Eraser {
 public printName() {
  console.log('this is an eraser');
 }
}
 
class Notebook {
 public printName() {
  console.log('this is a notebook');
 }
}
 
class Student {
 pencil: Pencil;
 eraser: Eraser;
 notebook: Notebook;
 public constructor(notebook: Notebook, pencil: Pencil, eraser: Eraser) {
  this.notebook = notebook;
  this.pencil = pencil;
  this.eraser = eraser;
 }
 public write() {
  if (!this.notebook || !this.pencil) {
   throw new Error('Dependencies not provided!');
  }
  console.log('writing...');
 }
 public draw() {
  if (!this.notebook || !this.pencil || !this.eraser) {
   throw new Error('Dependencies not provided!');
  }
  console.log('drawing...');
 }
}

var dependenciesMap = {};
var injector = {
 resolve: function (constructor) {
  var dependencies = dependenciesMap[constructor.name];
  dependencies = dependencies.map(function (dependency) {
   return new dependency();
  });
  // 如果可以使用ES6的語(yǔ)法，下面的代碼可以合并為一行：
  // return new constructor(...dependencies);
  var mockConstructor: any = function () {
   constructor.apply(this, dependencies);
  };
  mockConstructor.prototype = constructor.prototype;
  return new mockConstructor();
 }
};
function Inject(...dependencies) {
 return function (constructor) {
  dependenciesMap[constructor.name] = dependencies;
  return constructor;
 };
}

// 裝飾器的使用非常簡(jiǎn)單，只需要在類(lèi)定義的上方添加一行代碼
// Inject是裝飾器的名字，后面是function Inject的參數(shù)
@Inject(Notebook, Pencil, Eraser)
class Student {
 pencil: Pencil;
 eraser: Eraser;
 notebook: Notebook;
 public constructor(notebook: Notebook, pencil: Pencil, eraser: Eraser) {
  this.notebook = notebook;
  this.pencil = pencil;
  this.eraser = eraser;
 }
 public write() {
  if (!this.notebook || !this.pencil) {
   throw new Error('Dependencies not provided!');
  }
  console.log('writing...');
 }
 public draw() {
  if (!this.notebook || !this.pencil || !this.eraser) {
   throw new Error('Dependencies not provided!');
  }
  console.log('drawing...');
 }
}
var student = injector.resolve(Student);
console.log(student instanceof Student); // true
student.notebook.printName(); // this is a notebook
student.pencil.printName(); // this is a pencil
student.eraser.printName(); // this is an eraser
student.draw(); // drawing
student.write(); // writing

function RadicalInject(...dependencies){
 var wrappedFunc:any = function (target: any) {
  dependencies = dependencies.map(function (dependency) {
   return new dependency();
  });
  // 使用mockConstructor的原因和上例相同
  function mockConstructor() {
   target.apply(this, dependencies);
  }
  mockConstructor.prototype = target.prototype;
 
  // 為什么需要使用reservedConstructor呢？因?yàn)槭褂肦adicalInject對(duì)Student方法裝飾之后，
  // Student指向的構(gòu)造函數(shù)已經(jīng)不是一開(kāi)始我們聲明的class Student了，而是這里的返回值，
  // 即reservedConstructor。Student的指向變了并不是一件不能接受的事，但是如果要
  // 保證student instanceof Student如我們所期望的那樣工作，這里就應(yīng)該將
  // reservedConstructor的prototype屬性指向原Student的prototype
  function reservedConstructor() {
   return new mockConstructor();
  }
  reservedConstructor.prototype = target.prototype;
  return reservedConstructor;
 }
 return wrappedFunc;
}

@RadicalInject(Notebook, Pencil, Eraser)
class Student {
 pencil: Pencil;
 eraser: Eraser;
 notebook: Notebook;
 public constructor() {}
 public constructor(notebook: Notebook, pencil: Pencil, eraser: Eraser) {
  this.notebook = notebook;
  this.pencil = pencil;
  this.eraser = eraser;
 }
 public write() {
  if (!this.notebook || !this.pencil) {
   throw new Error('Dependencies not provided!');
  }
  console.log('writing...');
 }
 public draw() {
  if (!this.notebook || !this.pencil || !this.eraser) {
   throw new Error('Dependencies not provided!');
  }
  console.log('drawing...');
 }
}
// 不再出現(xiàn)injector，直接調(diào)用構(gòu)造函數(shù)
var student = new Student();
console.log(student instanceof Student); // true
student.notebook.printName(); // this is a notebook
student.pencil.printName(); // this is a pencil
student.eraser.printName(); // this is an eraser
student.draw(); // drawing
student.write(); // writing

interface NotebookInterface {
 printName(): void;
}
interface PencilInterface {
 printName(): void;
}
interface EraserInterface {
 printName(): void;
}
interface StudentInterface {
 notebook: NotebookInterface;
 pencil: PencilInterface;
 eraser: EraserInterface;
 write(): void;
 draw(): void;
}
class Notebook implements NotebookInterface {
 public printName() {
  console.log('this is a notebook');
 }
}
class Pencil implements PencilInterface {
 public printName() {
  console.log('this is a pencil');
 }
}
class Eraser implements EraserInterface {
 public printName() {
  console.log('this is an eraser');
 }
}
 
class Student implements StudentInterface {
 notebook: NotebookInterface;
 pencil: PencilInterface;
 eraser: EraserInterface;
 constructor(notebook: NotebookInterface, pencil: PencilInterface, eraser: EraserInterface) {
  this.notebook = notebook;
  this.pencil = pencil;
  this.eraser = eraser;
 }
 write() {
  console.log('writing...');
 }
 draw() {
  console.log('drawing...');
 }
}

import { Inject } from "inversify";
 
@Inject("NotebookInterface", "PencilInterface", "EraserInterface")
class Student implements StudentInterface {
 notebook: NotebookInterface;
 pencil: PencilInterface;
 eraser: EraserInterface;
 constructor(notebook: NotebookInterface, pencil: PencilInterface, eraser: EraserInterface) {
  this.notebook = notebook;
  this.pencil = pencil;
  this.eraser = eraser;
 }
 write() {
  console.log('writing...');
 }
 draw() {
  console.log('drawing...');
 }
}

import { TypeBinding, Kernel } from "inversify";
 
var kernel = new Kernel();
kernel.bind(new TypeBinding<NotebookInterface>("NotebookInterface", Notebook));
kernel.bind(new TypeBinding<PencilInterface>("PencilInterface", Pencil));
kernel.bind(new TypeBinding<EraserInterface>("EraserInterface", Eraser));
kernel.bind(new TypeBinding<StudentInterface>("StudentInterface", Student));

var student: StudentInterface = kernel.resolve<StudentInterface>("StudentInterface");
console.log(student instanceof Student); // true
student.notebook.printName(); // this is a notebook
student.pencil.printName(); // this is a pencil
student.eraser.printName(); // this is an eraser
student.draw(); // drawing
student.write(); // writing