Support local flow-bin

[wpcarro]

Any plans to support the local flow-bin executable via something like npx flow ...? That would be nice, so that project-specific flow-bin versions could be used instead of depending on a globally installed version. Other editor tools in the npm ecosystem support this if we need to draw from a precedent.

[aaronjensen]

I use this:

(defun flow/set-flow-executable ()
  (interactive)
  (let* ((os (pcase system-type
               ('darwin "osx")
               ('gnu/linux "linux64")
               (_ nil)))
         (root (locate-dominating-file  buffer-file-name  "node_modules/flow-bin"))
         (executable (car (file-expand-wildcards
                           (concat root "node_modules/flow-bin/*" os "*/flow")))))
    (setq-local flow-minor-default-binary executable)
    (setq-local company-flow-executable executable)
    (setq-local flycheck-javascript-flow-executable executable)))

(add-hook 'rjsx-mode-hook #'flow/set-flow-executable t)

I'm not sure about supporting this in the library out of the box, but maybe that'd be ok.

[wpcarro]

Thanks for sharing this snippet! I'll certainly be using this myself. From what I've seen, I know many people prefer using local bins whenever possible. Using npx is a great way to access the node_modules/.bin/flow call, which you may be able to use to simplify some of the finding logic in your function.

From a design philosophy, why not support a variable for activating the preference?

E.g. -

(setq company-flow-prefer-local-bin t)

[aaronjensen]

Personally, I wouldn't use npx for this as it increases startup time:

$ time npx flow version
Flow, a static type checker for JavaScript, version 0.65.0
npx flow version  0.14s user 0.11s system 95% cpu 0.263 total

$ time ./node_modules/.bin/flow version
Flow, a static type checker for JavaScript, version 0.65.0
./node_modules/.bin/flow version  0.10s user 0.07s system 96% cpu 0.172 total

$ time ./node_modules/flow-bin/flow-osx-v0.65.0/flow version
Flow, a static type checker for JavaScript, version 0.65.0
./node_modules/flow-bin/flow-osx-v0.65.0/flow version  0.01s user 0.01s system 84% cpu 0.023 total

Using the bin for flow directly is slower as well. That's why I path to the actual binary.

For this library, building that in may make sense since the logic is somewhat complicated and it makes a big difference in the performance/usability of company-flow.

[aaronjensen]

I updated the readme w/ the snippet. Hopefully that helps some people, but I'll still consider building this in.

[wpcarro]

Thanks for the explanation. I think I share your concerns about the time that npx pads in. I will definitely make use of that snippet for now and I'll stay tuned for any package updates!