英文:
What's the point of importing and exporting at the same time in the same typescript file
问题
我阅读了chart.js的源文件，发现以下几行代码：
export * from './controllers/index.js'';
export * from './core/index.js'';
export * from './elements/index.js'';
export * from './platform/index.js'';
export * from './plugins/index.js'';
export * from './scales/index.js'';
import * as controllers from './controllers/index.js';
import * as elements from './elements/index.js';
import * as plugins from './plugins/index.js';
import * as scales from './scales/index.js';
export {
controllers,
elements,
plugins,
scales,
};
我稍微理解了这段代码，但对于其中的这行代码import * as controllers from './controllers/index.js'，然后将其导出为不同的简单名称controllers，我不太确定。
但为什么要这样做export * from './controllers/index.js'; 好像重复导入/导出了相同的包。
我搜索了一下，发现许多TypeScript脚本都这样做。有人可以解释一下这段代码的好处/原因吗？
这不会导致任何依赖循环问题吗？
我明白了。我看到很多示例都这样做。我想这是基于TypeScript的某种约定。
英文:
I read chart.js source files found lines below:
export * from './controllers/index.js';
export * from './core/index.js';
export * from './elements/index.js';
export * from './platform/index.js';
export * from './plugins/index.js';
export * from './scales/index.js';
import * as controllers from './controllers/index.js';
import * as elements from './elements/index.js';
import * as plugins from './plugins/index.js';
import * as scales from './scales/index.js';
export {
controllers,
elements,
plugins,
scales,
};
I understand slightly but not sure enough with the line import * as controllers from './controllers/index.js'; and then export it as a different simple name controllers.
But why export * from './controllers/index.js'; It seems do duplicate things as import/export the same package.
I search that many ts script is doing like this. Can someone please give some explanation for the benefit/reason of this piece of code?
Won't this cause any dependecy loop issue?
Understand. I saw multiple samples doing this. I thought it based some convention of TS.
答案1
得分: 1
这会重复导出相同的内容，但方式略有不同。
这个
export * from './controllers/index.js';
会将其他文件中的所有导出内容重新导出，保持它们原始的导出名称。例如，如果该文件有 export const foo = 'foo';，上面的代码将创建一个名为 foo 的具名导出。它允许通过此文件使用 controllers，如下所示：
import foo from './thepath.js';
console.log(foo);
但这个
import * as controllers from './controllers/index.js';
export {
controllers,
将所有导入内容放入一个单一的具名导出中，这个导出是一个名为 controllers 的命名空间对象。它允许通过此文件使用 controllers，如下所示：
import { controllers } from './thepath.js';
console.log(controllers.foo);
因此，它会重复导出内容，但这可能是有意为之，以便模块的使用者有更多选择。这种重复并不是必需的，只是他们决定采用的设计选择。
这不会导致任何依赖循环吗？
不会，没有循环依赖。
英文:
They do import/export the same thing, but in slightly different ways.
This
export * from './controllers/index.js';
will re-export all exports from that other file under their original export names. For example, if that file has export const foo = 'foo';, that above line will create a named export named foo. It allows the use of controllers through this file with:
import foo from './thepath.js';
console.log(foo);
But this
import * as controllers from './controllers/index.js';
export {
controllers,
instead takes all the imports and puts them into a single named export, a namespace object called controllers. It allows the use of controllers through this file with:
import { controllers } from './thepath.js';
console.log(controllers.foo);
So it is duplicating exports, but that may well be deliberate so that consumers of the module find it handy to have more options. Such duplication isn't necessary, just a design choice they decided to go with.
>Won't this cause any dependency loop?
No, there's no circular dependency.
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