TypeScript中的工厂返回类 [英] Factory returning classes in TypeScript

问题描述

根据输入数据编写一个库；创建类并在主类中使用它们.

Wrote a library that, depending on the input data; creates classes and uses them inside a main class.

为了使代码更具可维护性和可读性，我将类生成逻辑移到了一个单独的文件中，该文件可以导出工厂函数.

To make the code more maintainable and readable, I've moved the class generation logic into a separate file that exports a factory function.

代码是在ES2015中编写的.现在，我要迁移到TypeScript.

Code was written in ES2015. Now I'm migrating to TypeScript.

这是一个伪示例:

export default function (foo:string) => {
    class A {
        value:string = foo + '-A';
    }

    return { A };
};

Main.ts

import factory from './factory';

export default class Main {
    private inner:any;
    constructor(foo:string) {
        this.inner = factory(foo);
    }
    get a() {
        return new this.inner.A();
    }
}

用法:

let main = new Main('bar');
console.log(main.a.value); // "bar-A"

问题:

• TS编译器错误:
  模块的默认导出具有或正在使用私有名称'A'.
• 在 Main 类中无法将getter a 的类型定义为 A (例如， get a():A {...}

Problems:

• TS compiler error:
  Default export of the module has or is using private name 'A'.
• Cannot define the type of the getter a as A in Main class (e.g. get a():A { ... }

您将如何解决(将工厂类保存在单独的文件中)?还是应该更改设计模式?

How would you resolve this (keeping the factory classes in a separate file)? Or should I change the design pattern?

推荐答案

诸如此类的事情

export interface Base {}

export interface IA extends Base {
    value: string;
}

export type Builders = {
    [name: string]: { new <T extends Base>(): T };
}

export function factory(foo: string): Builders {
    class A implements IA {
        value:string = foo + '-A';
    }

    return { A };
};

并且:

import { factory, IA, Builders } from './Factory';

export default class Main {
    private inner: Builders;

    constructor(foo:string) {
        this.inner = factory(foo);
    }

    get a():IA {
        return new this.inner.A() as IA;
    }
}

---

编辑

factory.ts 怎么了?

export class Base {}

export type Builders = {
    [name: string]: { new <T extends Base>(): T };
}

class A extends Base {
    value: string;

    constructor();
    constructor(foo: string);
    constructor(foo?: string) {
        super();
        this.value = foo + "-A";
    }
}

// more classes...

export function factory(foo: string): Builders {
    return { A: A.bind(A, foo) };
};

与您所做的基本上相同，只是这些类未在该类内部定义，并且已导出，因此不需要我建议的接口.
同样，通过这种方式，所有类仅被评估一次，而不是每次调用 factory 函数时都会被评估.

It's basically the same as what you did, just that the classes are not defined inside the class, and are exported so no need for the interfaces I suggested.
Also, this way all the classes will only be evaluated once and not every time the factory function is invoked.

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