NodeJS's __filename/__dirname in ES6 Modules

Bradley Meck bradley.meck at gmail.com
Sat Jan 21 17:02:38 UTC 2017


Please see
https://github.com/tc39/proposal-dynamic-import#an-actual-function

As per `"currentDir()" and "currentFile()"` this may not make sense for all
URLs. Please use https://url.spec.whatwg.org/ which ships in Node v7+ under
`require('url').URL` and the proposal to bring it into the language itself
https://github.com/jasnell/proposal-url . Getting the "directory" of a URL
would be ~= `new URL('.', file_url)`.

On Sat, Jan 21, 2017 at 10:42 AM, Gil Tayar <gil at tayar.org> wrote:

> Thanks!
>
> Makes total sense. So why not have Domenic's "import" be a real function
> that comes from this "js:context", thus obviating the need for a new
> JavaScript operator?
>
> While I realize that "js:context" will a Node thing, we could have a
> special import (e.g. import {...} from "js:system") that enables the system
> to expose real functions, of which one is "dynamicImport" and others would
> be "currentDir()" and "currentFile()".
>
> In other words - Domenic exposed a real need, but it seems that this need
> is more general, and not specific only to dynamic import, and should be
> added to the spec as a special import, just like it may be in Node.
>
>
> On Fri, Jan 20, 2017 at 6:48 PM Bradley Meck <bradley.meck at gmail.com>
> wrote:
>
>> The current trend is towards the https://github.com/nodejs/
>> node-eps/pull/39 rewrite which does not have magic variables
>> https://github.com/bmeck/node-eps/blob/b14276ca093fac9cbc3b72ff5433df
>> 35ae67fb59/002-es-modules.md#341-environment-variables
>>
>> There are ideas about exposing the URL of the current ESM via something
>> like https://docs.google.com/presentation/d/1aq_
>> QjBUQTovj9aQZQrVzS7l1aiOs3ZNlk7wgNTUEMy0/edit#slide=id.g16ab11d101_0_22
>>
>> On Fri, Jan 20, 2017 at 10:42 AM, Gil Tayar <gil at tayar.org> wrote:
>>
>> While reading Dominic Denicola's spec for dynamic import() at
>> https://github.com/tc39/proposal-dynamic-import, I read his rational for
>> not having import be a regular function, but rather a "syntactic form". The
>> idea is that import() needs to be "in the scope" of the current module, as
>> it needs to resolve the module path it is given relative to the current
>> module's.
>> Thinking about it some more, I thought it would be a pity for import to
>> be so "special", and asked myself whether there will be more features that
>> will need to be "module-aware" like import().
>>
>> And there are! (I think...) - __filename and __dirname in NodeJS are
>> exactly such features. Actually, anything passed to the function wrapping
>> each NodeJS module is such a feature, but going over them, only __filename
>> and __dirname are not immediately related to the module mechanism.
>>
>> So my question is this (and it is specifically addressed to the NodeJS
>> implementors in the group): in NodeJS's implementation of ES6 modules, how
>> will __dirname and __filename be implemented? Will there still be a
>> function wrapper like in the current module implementation? Or will
>> __dirname and __filename be a "syntactic form" like import()? Or something
>> else?
>>
>> Thanks,
>> Gil Tayar
>>
>> _______________________________________________
>> es-discuss mailing list
>> es-discuss at mozilla.org
>> https://mail.mozilla.org/listinfo/es-discuss
>>
>>
>>
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