let department: Department;//ok to create a reference to an abstract typedepartment =newDepartment();//error: cannot create an instance of an abstract classdepartment =newAccountingDepartment();//ok to create and assign a non-abstract subclassdepartment.printName(); department.printMeeting(); dep...
// Property 'x' is protected and only accessible through an instance of class 'Derived2'. This is an instance of class 'Base'. } } 例如,Java 认为这是合法的。 另一方面,C# 和 C++ 选择此代码应该是非法的。 TypeScript 在这里支持 C# 和 C++,因为在Derived2中访问x应该只在Derived2的子类中是...
// Cannot create an instance of an abstract class. 抽象类通过子类来实现,子类继承了抽象类的属性和方法 class Cat extends Animal{ } const cat = new Cat('miaomiao') console.log(cat.name) 上述示例中,Cat继承了抽象类Animal,并且能够拥有Animal的属性name 抽象类方法和接口相似,只定义方法,不包含方法体...
The constructor is a special function used to create and initialize objects based on the class. When you create a new instance of the class, the constructor creates a new object with the class shape and initializes it with the values passed to it. Accessors are a type of fu...
function greet(ctor: typeof Base) { const instance = new ctor(); // Cannot create an instance of an abstract class. instance.printName(); } TypeScript 会报错,告诉你正在尝试实例化一个抽象类。毕竟,根据 greet 的定义,这段代码应该是合法的:/...
class和abstract class的区别主要是abstract class不能被实例化: abstractHuman{name: string; abstractlang():void;toString() {return`<human:${this.name}>`} }newHuman// Cannot create an instance of an abstract class. 4. interface和abstract class ...
// egclassGreeter{greeting:string;constructor(message:string){// this 成员访问符this.greeting=message;}greet(){return"Hello, "+this.greeting;}} 通过new方法创建类的instance,这将调用我们在类中定义的constructor(构造函数),它将完成两件事: 创建一个和Greeter类一样Shape的新对象,然后通过constructor里面的...
abstract class Animal { public name; public constructor(name) { this.name = name; } public abstract sayHi(); } let a = new Animal('Jack'); // index.ts(9,11): error TS2511: Cannot create an instance of the abstract class 'Animal'.复制代码 ...
Object.create(b):(__.prototype=b.prototype,new__());};})();varShape=/** @class*/(function(){functionShape(a){this.Area=a;}returnShape;}());varCircle=/** @class*/(function(_super){__extends(Circle,_super);functionCircle(){return_super!==null&&_super.apply(this,arguments)||...
Object.create(b) : (__.prototype = b.prototype, new __()); }; })(); var Root = /** @class */ (function () { function Root() { } return Root; }()); var Child = /** @class */ (function (_super) { __extends(Child, _super); function Child() { return _super !==...