Question

方法返回一个类类型：Widget。

我想使用以下代码创建此类型的对象：

const wType = def.getWidgetType(); // returns Widget as type
const obj = new wType('foo'); // use the const like a normal type with parameters

getWidgetType（）

public getWidgetType(): any {
 return TextWidget;
}

错误

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

有没有＆＃34;很好＆＃34; version（没有eval）创建具有给定类类型的对象？

Answer 1

假设getWidgetType返回的是构造函数，只要new wType('foo')的签名明确声明它返回构造函数签名，就可以调用getWidgetType。

例如，此代码有效：

class Definition<T> {
    // Takes in a constructor
    constructor(public ctor: new (p: string) => T) {

    }
    // returns a constructor (aka a function that can be used with the new operator)
    // return type annotation could be inferred here, was added for demonstrative purposes 
    getWidgetType() : new (p: string) => T{
        return this.ctor;
    }
}

const def = new Definition(class {
    constructor(p: string) {}
});

const wType = def.getWidgetType();
const obj = new wType('foo')

Typescript创建一个来自变量

1 个答案: