nbb.core/*file* doesn't survive bundle

[chr15m]

I am not sure if this is a bug or a feature request.

nbb v1.3.196
Ubuntu 22.04
Node v20.17.0

If you run nbb bundle printme.cljs -o printme.mjs and run the resulting script with node printme.mjs, any reference to nbb.core/*file* doesn't survive.

(ns printme
  (:require [nbb.core :refer [*file*]]))
(print *file*)

npx nbb bundle printme.cljs -o printme.mjs
npx nbb printme.cljs # outputs the path to the script
node printme.mjs # outputs nil

I expected *file* to be the .mjs script's location.

I can hack around this for now of course but I thought I'd file it just in case.

[chr15m]

Actually I don't think I can hack around it. As far as I can tell there is currently no way to get the path to the transformed js file:

$ cat printme.cljs 
(ns printme
  (:require [nbb.core :refer [*file*]]))

(print "#-> printme")

(print "__filename" js/__filename)
(print "globalThis.__filename" (aget js/globalThis "__filename"))
(print "*file*" *file*)

$ npm run build-mjs; npx nbb printme.cljs; node dist/printme.mjs

> build-mjs
> mkdir -p dist; nbb bundle printme.cljs -o dist/printme.mjs

#-> printme
__filename nil
globalThis.__filename nil
*file* /home/chrism/dev/repro-nbb-file-bundle/printme.cljs
#-> printme
__filename nil
globalThis.__filename nil
*file* nil

Unfortunately none of these vars survives. A possible fix would be allowing/setting __filename.

[chr15m]

Ok I learned that __filename doesn't existing in esm 🤯

Some suggest import.meta.url, but import seems to be a promise, and .meta is nil.

However, (aget js/process "argv" 1) seems to do what I want. 🎉

It works via (or *file* (aget js/process "argv" 1)) in both the .cljs and bundled .mjs file:

EITHER /home/chrism/dev/repro-nbb-file-bundle/printme.cljs
EITHER /home/chrism/dev/repro-nbb-file-bundle/printme.mjs

So I'll use this for now.

[borkdude]

*file* always points to the original source file so it doesn't make sense to fix this for "bundles" imo. the argv approach is probably the most reliable way.