How to activate semantic-mode for specific major modes only?

Question

I've seen this question a lot. But none of the replies fixed my issue: the minor mode stays on in others modes.

So far, I have tried:

(use-package stickyfunc-enhance
  :config
  ;; (add-to-list 'semantic-default-submodes 'global-semantic-stickyfunc-mode)
  ;; (defun turn-on-semantic () (semantic-mode 1) (require 'stickyfunc-enhance))
  ;; (add-hook 'python-mode-hook 'turn-on-semantic)
  (add-hook 'python-mode-hook
            (lambda ()
              (add-to-list 'semantic-default-submodes 'global-semantic-stickyfunc-mode)
              (semantic-mode 1)
              (require 'stickyfunc-enhance))))

My issue with those 2 approaches is that semantic-mode will stay on in all major modes once I visited a Python buffer.

How can I turn off semantic-mode in all other modes? Do I have to manually turn it off on prog-mode-hook?

---

Trying kaushalmodi's solution:

(use-package stickyfunc-enhance
  :init
  (add-to-list 'semantic-default-submodes 'global-semantic-stickyfunc-mode)
  :config
  (defun me/enable-semantic-maybe ()
    "Maybe enable `semantic-mode'."
    (if (derived-mode-p 'python-mode)
        (lambda ()
          (semantic-mode 1)
          (require 'stickyfunc-enhance))
      (semantic-mode -1)))
  (add-hook 'change-major-mode-hook #'me/enable-semantic-maybe))

Yields me:

Making python-shell-interpreter local to  *Python Internal [792caf12c778150badeeede64c068cee]* while let-bound!
Making python-shell-interpreter-args local to  *Python Internal [792caf12c778150badeeede64c068cee]* while let-bound!

Answer 1

The best solution I have found to restrict semantic-mode to certain buffers only is to set semantic-inhibit-functions. For example you can add a function that inhibits semantic in buffers not in python mode as follows

(defun my-inhibit-semantic-p ()
  (not (equal major-mode 'python-mode)))

(with-eval-after-load 'semantic
      (add-to-list 'semantic-inhibit-functions #'my-inhibit-semantic-p))

Answer 2

Looking at the source code in semantic.el, it looks like semantic-mode is a global minor mode. So once activated, it will be activated in all the buffers; and once deactivated, it will be deactivated in all.

---

You can probably have something like below that enables semantic mode only when you open a specific mode buffer (but I am not sure how well it will behave when you have buffers open with different major modes):

(defun my/enable-semantic-mode-maybe ()
  (if (derived-mode-p 'python-mode)
      (semantic-mode 1)
    (semantic-mode -1)))
(add-hook 'change-major-mode-hook #'my/enable-semantic-mode-maybe)

---

From semantic.el:

(define-minor-mode semantic-mode
  "Toggle parser features (Semantic mode).
With a prefix argument ARG, enable Semantic mode if ARG is
positive, and disable it otherwise.  If called from Lisp, enable
Semantic mode if ARG is omitted or nil.

;; -- snip --     

\\{semantic-mode-map}"
  :global t ; <-- GLOBAL MODE

;; -- snip --