Do Anonymous Exports Solve the Backwards Compatibility Problem?

Domenic Denicola domenic at domenicdenicola.com
Wed Dec 19 20:20:56 PST 2012


> -----Original Message-----
> From: es-discuss-bounces at mozilla.org [mailto:es-discuss- bounces at mozilla.org] On Behalf Of Brendan Eich
> Sent: Wednesday, December 19, 2012 23:11


> In a thread you may not have caught up on, Andreas did argue for a special form such as

> module foo at "foo";

> for anonymous import, so that the system can check that "foo" indeed does

> export = ...

> and throw otherwise. Sorry if you did see this and reply (in which case I missed the reply!). If not, whaddya think?

IMO this is undesirable. In such a situation, modules can no longer be abstraction boundaries. Instead you must peek inside each module and see which form it exported itself using.

If we instead had

import foo from "foo";

where `foo` became either the module instance object (in the multi-export case) or the singly-exported value (single-export case), abstraction boundaries are preserved much more neatly.

This goes both ways, of course. I.e., ideally, this should work too:

```js
module "glob" {
    function glob() {
    }
    glob.sync = function () { };
}

import { sync } from "glob";
```

(see https://npmjs.org/package/glob)

This was much of the motivation behind Yehuda and I's proposal, FWIW.


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