TypeScript：扩展导入的枚举

TypeScript: extending imported enum

提问by smnbbrv

I can merge enum declarations within a single file e.g.

我可以在单个文件中合并枚举声明，例如

export enum Test {
  value1 = <any>'value1',
  value2 = <any>'value2'
}

export enum Test {
  value3 = <any>'value3'
}

This works fine, but my intention is to have a shared enum which I can extend later, e.g.

这工作正常，但我的目的是有一个共享的枚举，我可以稍后扩展，例如

// test.enum.ts
export enum Test {
  value1 = <any>'value1',
  value2 = <any>'value2'
}

// place-to-extend-enum.ts
import { Test } from './test.enum';

export enum Test {
  value3 = <any>'value3'
}

What I get is

我得到的是

Individual declarations in merged declaration 'Test' must be all exported or all local.

合并声明“测试”中的单个声明必须全部导出或全部为本地声明。

Is there a way to achieve the desired behaviour?

有没有办法实现所需的行为？

回答by Chklang

In refer to https://github.com/Microsoft/TypeScript/pull/6213you can do :

在参考https://github.com/Microsoft/TypeScript/pull/6213你可以这样做：

// test.enum.ts
export enum Test {
  value1 = <any>'value1',
  value2 = <any>'value2'
}

// place-to-extend-enum.ts
import { Test } from './test.enum';

declare module './test.enum' {
  export enum Test {
    value3 = <any>'value3'
  }
}

... Magic! ;)

... 魔法！;)

回答by VJPPaz

I saw a way that you can add additional function/method in an existing enum. this is by create the function within a namespace similar to the enum type: Here

我看到了一种可以在现有枚举中添加附加功能/方法的方法。这是通过在类似于枚举类型的命名空间中创建函数：这里

enum Weekday {
    Monday,
    Tuesday,
    Wednesday,
    Thursday,
    Friday,
    Saturday,
    Sunday
}
namespace Weekday {
    export function isBusinessDay(day: Weekday) {
        switch (day) {
            case Weekday.Saturday:
            case Weekday.Sunday:
                return false;
            default:
                return true;
        }
    }
}

const mon = Weekday.Monday;
const sun = Weekday.Sunday;
console.log(Weekday.isBusinessDay(mon)); // true
console.log(Weekday.isBusinessDay(sun)); // false

You can see the complete information here https://basarat.gitbooks.io/typescript/docs/enums.htmlat section "Enum with static functions"

您可以在此处https://basarat.gitbooks.io/typescript/docs/enums.html的“具有静态函数的枚举”部分查看完整信息

回答by smnbbrv

After some research I must admit I cannot find a super-proper way to do that.

经过一些研究，我必须承认我找不到一种非常合适的方法来做到这一点。

But there are two possible solutions that are not that bad and not stinking that much.

但是有两种可能的解决方案，既不那么糟糕，也不那么臭。

First is implementing a custom enum - this way is not allowing to consume already existing enums. This is probably the only limitation of this method. Other than that it looks simple and quite native.

首先是实现自定义枚举 - 这种方式不允许使用已经存在的枚举。这可能是这种方法的唯一限制。除此之外，它看起来简单而且非常原生。

Another way is a big hackaround with [merging enums into one value with a separate type declaration. This way allows to consume already existing, realenums; however it is less comfortable to use because there are two entities to be aware of: enum value and enum type.

另一种方法是[将枚举合并为一个具有单独类型声明的值的大hackaround。这种方式允许使用已经存在的真实枚举；但是使用起来不太舒服，因为有两个实体需要注意：枚举值和枚举类型。