Emacs: Use column-number-mode in prog-mode / text-mode only

.emacs.d/lisp/functions.el

@@ -408,15 +408,20 @@ This does not interfere with `subword-mode'."
     (modify-syntax-entry ?_ "_")
     (message "_ is a word delimiter")))
 
+(defun turn-on-column-number-mode ()
+  "Unconditionally turn on `column-number-mode' for the current buffer."
+  (set (make-variable-buffer-local 'column-number-mode) t))
+
+(defun turn-on-delete-trailing-whitespace ()
+  "Add the `delete-trailing-whitespace' function to `before-save-hook'.
+This does not affect .csv files."
+  (unless (string= (file-name-extension buffer-file-name) "csv")
+    (add-hook 'before-save-hook 'delete-trailing-whitespace nil t)))
+
 (defun turn-on-fmt-before-save ()
   "Unconditionally add the `fmt' function to `before-save-hook'."
   (add-hook 'before-save-hook 'fmt nil t))
 
-(defun turn-on-delete-trailing-whitespace ()
-  "Unconditionally add the `delete-trailing-whitespace' function to `before-save-hook'."
-  (unless (string= (file-name-extension buffer-file-name) "csv")
-    (add-hook 'before-save-hook 'delete-trailing-whitespace nil t)))
-
 (defun turn-off-indent-tabs ()
   "Unconditionally turn off tab indentation."
   (setq indent-tabs-mode nil))
@@ -425,6 +430,14 @@ This does not interfere with `subword-mode'."
   "Unconditionally turn on tab indentation."
   (setq indent-tabs-mode t))
 
+(defun turn-off-line-number-mode ()
+  "Unconditionally turn off `line-number-mode' fur the current buffer.."
+  (set (make-variable-buffer-local 'line-number-mode) nil))
+
+(defun turn-off-linum ()
+  "Unconditionally turn off Linum mode."
+  (linum-mode 0))
+
 (defun turn-on-newline-paragraph ()
   "Unconditionally make of newlines the start of a paragraph."
   (set (make-local-variable 'paragraph-start) "
@@ -437,10 +450,6 @@ This does not interfere with `subword-mode'."
   "Allow skeletons to make markers to ease field navigation."
   (add-hook 'skeleton-end-hook 'skeleton-make-markers))
 
-(defun turn-off-linum ()
-  "Unconditionally turn off Linum mode."
-  (linum-mode 0))
-
 (defun turn-on-tab-width-to-4 ()
   "Unconditionally set tab width to 4."
   (setq tab-width 4))

.emacs.d/lisp/main.el

@@ -47,9 +47,6 @@
 ;;; Enable all disabled commands.
 (setq disabled-command-function nil)
 
-;;; Print column number in mode line.
-(column-number-mode 1)
-
 ;;; Print buffer size in mode line.
 (size-indication-mode 1)
 
@@ -69,9 +66,8 @@
 ;;; Line numbers
 ;;; Adding to `find-file-hook' ensures it will work for every file, regardless of
 ;;; the mode, but it won't work for buffers without files nor on mode change.
-(defun turn-off-line-number-mode ()
-  (line-number-mode -1))
 (dolist (hook '(prog-mode-hook text-mode-hook))
+  (add-hook hook 'turn-on-column-number-mode)
   (add-hook hook 'turn-off-line-number-mode)
   (add-hook hook 'linum-mode))
 ;;; Emacs-nox does not display a fringe after the linum: Setting linum-format in