Disable minor mode in specific major-modes or changing buffers (i.e. selectrum for prog-modes but not in shell)

Question

This is similar to many other questions but nothing is leaping out..

I'm a fan of selectrum (similar to helm and ido I gather): e.g. hit M-x and start typing, it'll find matches and list them.

I'd like selectrum-mode enabled during all modes (at least prog-modes), but not during a shell (M-x shell); I'm fine with a specific list of modes to disable it (i.e. enable for all, then disable selectively) or enable for specific modes, i.e. it's handy during non-prog to find-file for opening, but when in shell I want regular shell (bash/etc) based tab completion to occur.

Simple enable of selectrum is:

(selectrum-mode +1)

But this is global in all modes, all the time, so the simpler tab-completion goes instead to selectrum.

I tried putting it in an add-hook:

(add-hook 'prog-mode-hook 'selectrum-mode)

but this just enables it globally when first entering a prog-mode, I think; its not limited to prog modes. And really, I'd like it on all the time, barring some modes. The question is can selectrum be non-global at all, and even if it's a global-only minor mode, can it be toggled on and off automagically?

Without changing selectrum-mode's code to be non-global (if that's possible), I wonder if there's a way to enable/disable it selectively per mode.

What is best practice?

If it's global, could it be toggled on and off when toggling buffers? Perhaps a code fragment to hook switching buffers and disable as appropriate; i.e. on switch buffer, check if entering the list of modes, and then check if selectrum-mode is on, and then (selectrum-mode -1) if needed. This seems cumbersome and likely there is a more elegant approach.

Your help is appreciated; always love to learn something!

edit: Noticed there is a hook buffer-list-update-hook which might be usable, so perhaps I'll learn enough elisp to build the if-mode-active disable code, but I'm sure there's a much more elegant solution.

Answer 1

Attempting answering my own question:

Try 1: partially works, but as per comments below doesn't seem reliable

Create a wrapper global mode, that is selective about when it enables.

(define-global-minor-mode my-global-selectrum-mode selectrum-mode
  (lambda ()
    (when (not (memq major-mode
                     (list 'shell-mode)))
      (selectrum-mode))))

(my-global-selectrum-mode 1)

edit: Try 2: Enable/disable the global minor mode on buffer changes

;; turn selectrum on globally
(selectrum-mode +1)
;; Turn off selectrum on first entry into a new comint-mode (shell) buffer.
(add-hook 'comint-mode-hook (lambda () (selectrum-mode -1)))
;; Toggle selectrum after every buffer switch, avoiding the minibuffer.
(add-hook 'buffer-list-update-hook
          (lambda ()
            (unless (eq major-mode 'minibuffer-inactive-mode)
              (selectrum-mode (if (derived-mode-p 'comint-mode) -1 +1)))))

Stolen from: https://lists.gnu.org/archive/html/help-gnu-emacs/2018-07/msg00002.html