Trouble adding post-self-insert-hook in define-minor-mode

Question

I am trying to write a minor mode that upon visiting a word, it manipulate it. There is a list of words which is parsed from a file. Here is the problem:

(define-minor-mode auto-gls-mode
  "Documentation goes here"
  :lighter " AGLS"
  ;(setq agls-list '("foo" "bar"))    <----------works
  (setq agls-list (agls-parse-acn-file)) <-------doesn't work
  (if auto-gls-mode
      (add-hook 'post-self-insert-hook
        'agls-check-word nil t)
    (remove-hook 'post-self-insert-hook
         'agls-check-word t)))

and the hooked function:

(defun agls-check-word ()
  "Check if the word is in the list"
  (if (= last-command-event 32)
      (do-some-stuff)))   

The agls-parse-acn-file is pretty long but in pseudo-elisp reads like this:

(defun agls-parse-acn-file()
  ;find-file-noselect
  ;while new-line
    ;extract keywords
    ;end
  local-list)

simply opens a file by find-file-noselect, parse it, extract keywords and return a list. The conundrum is that, if populate the list as pointed by arrow the function in add-hook get called properly. If I use populate the list by calling the parse function, as I type in buffers with minor mode activate, nothing happens (agls-check-word is not called)

Answer 1

Base on the comments, you changed the current buffer during agls-parse-acn-file, you can use the following instead:

(with-temp-buffer
  (insert-file-contents "path/to/file")
  (parse-the-file))