从Typescript中的Base类创建Child类的新实例 [英] Create new instance of Child class from Base class in Typescript

问题描述

我想通过 Base 类方法创建 Child 类的新实例.

I want to create new instance of Child class from Base class method.

这有点复杂，但是我会尽力解释.

It's a little bit complicated, but i will try to explain.

这是一个例子:

class Base(){
    constructor(){}

    clone(){
        //Here i want to create new instance
    }
}

class Child extends Base(){}


var bar = new Child();
var cloned = bar.clone();

clone instanceof Child //should be true!

所以.从这个示例中，我想克隆我的bar实例，该实例应该是Child

So. From this example i want to clone my bar instance, that should be instance of Child

好吧.我正在尝试在Bar.clone方法中进行跟踪:

Well. I'm trying following in Bar.clone method:

clone(){
    return new this.constructor()
}

...而且这在已编译的代码中有效，但是我遇到打字稿错误:

...And this works in compiled code, but i have typescript error:

error TS2351: Cannot use 'new' with an expression whose type lacks a call or construct signature.

有什么办法可以解决这个问题吗?

Any ideas how i can handle this?

谢谢.希望这对某人有帮助:)

Thank you. Hope this helps some1 :)

推荐答案

克隆未知对象时，您需要转换为通用对象.
最好的方法是使用<any>语句.

You need to cast to a generic object when cloning an unknown object.
The best way to do this is to use the <any> statement.

class Base {
    constructor() {

    }

    public clone() {
        return new (<any>this.constructor);
    }
}

class Child extends Base {

    test:string;

    constructor() {
        this.test = 'test string';
        super();
    }
}


var bar = new Child();
var cloned = bar.clone();

console.log(cloned instanceof Child); // returns 'true'
console.log(cloned.test); // returns 'test string'

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