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export questions

# Kevin Smith (13 years ago)

Four things:

  1. The export grammar on the wiki allows:

    export *;

Which I take to mean "export every local binding". What's the justification? I don't think I've ever seen a ES5 "module" that didn't have some local, non-exported state or function.

  1. The grammar also allows:

    export * from Path.To.Module;

which is fine. But I think it would also be convenient to provide the following:

export * from "SomeModule.js";

In particular, this form would be useful in "package main" files, where you are combining the interface of several sub-modules into a single package interface. Using only the allowed forms, we would need something like:

import "SomeModule.js" as SomeModule;
export * from SomeModule;

  1. I really like the module syntax (except for import *), and I would like to see convergence on the syntax for importing to a module instance:

    import "SomeModule.js" as SomeModule; // or module SomeModule = "SomeModule.js";

I personally like the former, but has there been any agreement on either one? Until there's a decision, we can't proceed with bleeding-edge transcompilation. : )

  1. Just a comment: the main argument in favor of "import *" is convenience. But it's nearly as convenient to import to a module instance:

    import "A.js" as A; A.x(); A.y();

This is indeed what Node.js programmers are used to and I don't believe there has been any gnashing of teeth over it. In my opinion, being able to statically analyze a module in isolation outweighs the additional convenience of import *.

Thanks for your time!

# 程劭非 (13 years ago)

I guess Kevin has some same concerns with me.

The four things point to one question: What should we do with the old ES3/ES5 libraries after we have module? (please correct me if you didn't mean that.)

ES3/ES5 libraries might be in more than one files and there are no “export” and "import" in it.

For example, I might want to use jQuery 1.3.2 in ES6, and I might could not modify the .js file for some reason.

I might want the following thing:

import "ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js" as jQuery var $ = jQuery.$;

And, a library might have dependencies, and they might not be using ES6 modules to manage their dependencies, I might want the following thing:

import "jquery.min.js", "MyES5Module.js" as MyES5Module var dosth = MyES5Module.dosth;

Currently harmony:modules might not strong enough to cover these cases. My proposal is :

  1. Export every thing by default. Since we have "import ... from ..." to protect our namespace there is no need to use “export”. If any author of library would like to hide local variable they will use anonymous function.

2.Allow multiple files in a module

in Variant A: "import URL" syntax

ModuleImport ::= StringLiteral "as" Id

===>

ModuleImport ::= StringLiteral ("," StringLiteral)* "as" Id

2012/8/29 Kevin Smith <khs4473 at gmail.com>:

# Shijun He (13 years ago)

On Fri, Aug 31, 2012 at 3:16 PM, 程劭非 <csf178 at gmail.com> wrote:

I guess Kevin has some same concerns with me.

The four things point to one question: What should we do with the old ES3/ES5 libraries after we have module? (please correct me if you didn't mean that.)

ES3/ES5 libraries might be in more than one files and there are no “export” and "import" in it.

For example, I might want to use jQuery 1.3.2 in ES6, and I might could not modify the .js file for some reason.

I might want the following thing:

import "ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js" as jQuery var $ = jQuery.$;

I'm using this pattern from 2006:

$import("jquery.min.js#jQuery,$")

translate to ES6 syntax:

import {$} from "jquery.min.js#jQuery"

That is, use URI fragment to identify the export names for old scripts. The loader will run the scripts in a sandbox and only export the specified names. This can be achieved in customized loader in current draft.

var myLoader = new Loader(System, { translate: function(src, relURL, baseURL, resolved) { var frag = new URL(relURL).fragment // URL class parse the url to uri components if (frag == null) return src var exportNames = src.split(/\s*,\s*/) return wrap(src, exportNames) // wrap the src with AMD-style function wrapper } })

But maybe System loader could support it directly.

# 程劭非 (13 years ago)

What does it look like if you want to import more than one variables from one module?

2012/8/31 Shijun He <hax.sfo at gmail.com>:

# Shijun He (13 years ago)

On Fri, Aug 31, 2012 at 6:24 PM, 程劭非 <csf178 at gmail.com> wrote:

What does it look like if you want to import more than one variables from one module?

import {a,b} from "oldscript.js#a,b"