[Emacs] Use nlinum-mode

dotfiles/emacs.d/README.org

@@ -998,6 +998,7 @@ This was stolen from https://github.com/jwiegley/dot-emacs
        (,mode-name ,disable-value)))
 
 (imalison:disable-mode-hook linum-mode)
+(imalison:disable-mode-hook nlinum-mode)
 (imalison:disable-mode-hook yas-minor-mode)
 #+END_SRC
 ** Other
@@ -1141,12 +1142,27 @@ I keep it around just in case I need it.
 (line-number-mode t)
 (column-number-mode t)
 #+END_SRC
-Linum can be really slow on large files so it does not make sense to
+*** nlinum
-have it on by default. Its probably safe to turn it on when in a
+Linum/NLinum can be really slow on large files so it does not make sense to have
-programming mode.
+it on by default. Its probably safe to turn it on when in a programming mode.
 #+BEGIN_SRC emacs-lisp
 (global-linum-mode -1)
-(add-hook 'prog-mode-hook (lambda () (linum-mode t)))
+#+END_SRC
+#+BEGIN_SRC emacs-lisp
+(use-package nlinum
+  :demand t
+  :config
+  (progn
+    (add-hook 'prog-mode-hook (lambda () (nlinum-mode t)))
+    (defun imalison-nlinum-mode-hook ()
+      (when nlinum-mode
+        (setq-local nlinum-format
+                    (concat "%" (number-to-string
+                                 ;; Guesstimate number of buffer lines.
+                                 (ceiling (log (max 1 (/ (buffer-size) 80)) 10)))
+                            "d"))))
+
+    (add-hook 'nlinum-mode-hook #'imalison-nlinum-mode-hook)))
 #+END_SRC
 ** Backups
 *** Put them all in one directory