如何使用Flow键入默认导出？ [英] How can I type a default export using Flow?

问题描述

// index.js
type complexThing = {
  a: string
}
type Thing = {
  x: number,
  y: boolean,
  z: complexThing
}

export default {
 x: 0,
 y: true,
 z: {a: 'hello'}
} : Thing // this says my default export is a Thing

可接受的选择：

或者，我不介意内联键入每个对象属性，但我认为这在语法上是不可能的：

Acceptable Alternative:

Alternatively, I wouldn't mind typing each of the object properties inline, but I think that's syntactically impossible:

export default {
 // I don't know how to add type signatures here
 x: 0, // number
 y: true, // boolean
 z: {a: 'hello'} // complexThing
}

不是我想要的：

我不想要做的是将变量存储到Flow类型：

Not What I Want:

What I don't want to do is store a variable just to to Flow type it:

// index.js
type complexThing = {
  a: string
}
type Thing = {
  x: number,
  y: boolean,
  z: complexThing
}

const myThing: Thing = {
 x: 0,
 y: true,
 z: {a: 'hello'}
}

export default myThing

推荐答案

你正在做类型转换所以你需要围绕对象的parens，例如更改

You are doing a typecast so you will need parens around the object, e.g. change

export default {
  x: 0,
  y: true,
  z: {a: 'hello'}
} : Thing

到

export default ({
  x: 0,
  y: true,
  z: {a: 'hello'}
} : Thing)

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