typescript - 合并不同文件中的 Typescript 接口(interface)和类

Question

在 Typescript 中，如果接口(interface)和类具有相同的名称并且位于同一文件中，则可以合并它们:

interface Test {
  example(input: 'a number'): number;
  example(input: 'a string'): string;
}

class Test {
  example(input: string): any {
    //return something
  }
}

const obj = new Test();
obj.example('a number'); //return type is number
obj.example('a string'); //return type is string
obj.example('something else'); //return type is any

但是似乎没有办法将这些接口(interface)定义拆分为多个文件，例如:

//test.interface.ts
export interface Test {
  example(input: 'a number'): number;
  example(input: 'a string'): string;
}

//test.class.ts
import "./test.interface.ts";

class Test {
  example(input: string): any {
    //return something
  }
}

const obj = new Test();
obj.example('a number'); //return type is any but should be number
obj.example('a string'); //return type is any but should be string
obj.example('something else'); //return type is any

将类和实际接口(interface)之间的接口(interface)定义拆分为多个文件的正确方法是什么？

Answer 1

此问题的解决方案是重新声明“托管” typescript 模块以扩充其定义:

//test.interface.ts
declare module './test.class.ts' {
  interface Test {
    example(input: 'a number'): number;
    example(input: 'a string'): string;
  }
}

//test.class.ts
import "./test.interface.ts";

class Test {
  example(input: string): any {
    //return something
  }
}

const obj = new Test();
obj.example('a number'); //return type is number
obj.example('a string'); //return type is string
obj.example('something else'); //return type is any