javascript 如何导出从另一个文件导入的 Flow 类型定义？
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How do you export a Flow type definition that is imported from another file?
提问by ide
Given a type definition that is imported from another module, how do you re-export it?
给定从另一个模块导入的类型定义，您如何重新导出它？
/**
* @flow
*/
import type * as ExampleType from './ExampleType';
...
// What is the syntax for exporting the type?
// export { ExampleType };
回答by Gabe Levi
The simplest form of this question is "how do I export a type alias?" and the simple answer is "with export type!"
这个问题最简单的形式是“如何导出类型别名？” 简单的答案是“用export type！”
For your example, you can write
对于你的例子，你可以写
/**
* @flow
*/
import type * as ExampleType from './ExampleType';
export type { ExampleType };
You may ask "why is ExampleTypea type alias?" Well, when you write
你可能会问“为什么是ExampleType类型别名？” 那么，当你写
type MyTypeAlias = number;
You are explicitly creating the type alias MyTypeAliaswhich aliases number. And when you write
您正在显式创建MyTypeAliasaliases的类型别名number。当你写
import type { YourTypeAlias } from './YourModule';
You are implicitly creating the type alias YourTypeAliaswhich aliases the YourTypeAliasexport of YourModule.js.
您正在隐式创建类型别名YourTypeAlias，该别名YourTypeAlias为YourModule.js.
回答by locropulenton
The following works nicely
以下效果很好
export type { Type } from './types';
回答by Gunther
The accepted answer is old and throwing warnings on my end. Given the amount of views, here's an updated answer that's compatible with flow 0.10+ .
接受的答案是旧的，并对我发出警告。鉴于观看次数，这里有一个与 flow 0.10+ 兼容的更新答案。
MyTypes.js:
MyTypes.js：
export type UserID = number;
export type User = {
id: UserID,
firstName: string,
lastName: string
};
User.js:
用户.js：
import type {UserID, User} from "MyTypes";
function getUserID(user: User): UserID {
return user.id;
}
回答by James Ko
I just found a need one-liner to do this for ES6 default classes, building on @locropulenton's answer. Suppose you have
我刚刚发现需要单行代码来为 ES6 默认类执行此操作，基于@locropulenton 的回答。假设你有
// @flow
export default class Restaurants {}
in a Restaurants.jsfile. To export it from an index.jsfile in the same directory, do this:
在一个Restaurants.js文件中。要从index.js同一目录中的文件导出它，请执行以下操作：
export type {default as Restaurants} from './Restaurants';
