Use lexical-binding in text-mode.el

* lisp/textmodes/text-mode.el: Use lexical-binding.
(text-mode, paragraph-indent-minor-mode, text-mode-hook-identify):
Use setq-local.
(toggle-text-mode-auto-fill): Quote function symbols as such.
(center-line): Minor simplification.
* doc/lispref/modes.texi (Example Major Modes): Update code example
for these changes to text-mode.

2 files changed, 18 insertions, 23 deletions

diff --git a/doc/lispref/modes.texi b/doc/lispref/modes.texi
index 1afbc5a5cee..7b64a56b199 100644
--- a/doc/lispref/modes.texi
+++ b/doc/lispref/modes.texi
@@ -1291,10 +1291,9 @@ You can thus get the full benefit of adaptive filling
 Turning on Text mode runs the normal hook `text-mode-hook'."
 @end group
 @group
-  (set (make-local-variable 'text-mode-variant) t)
-  (set (make-local-variable 'require-final-newline)
-       mode-require-final-newline)
-  (set (make-local-variable 'indent-line-function) 'indent-relative))
+  (setq-local text-mode-variant t)
+  (setq-local require-final-newline mode-require-final-newline)
+  (setq-local indent-line-function #'indent-relative))
 @end group
 @end smallexample
 
diff --git a/lisp/textmodes/text-mode.el b/lisp/textmodes/text-mode.el
index 931faadb5bb..90bb3eb3b53 100644
--- a/lisp/textmodes/text-mode.el
+++ b/lisp/textmodes/text-mode.el
@@ -1,4 +1,4 @@
-;;; text-mode.el --- text mode, and its idiosyncratic commands
+;;; text-mode.el --- text mode, and its idiosyncratic commands  -*- lexical-binding: t -*-
 
 ;; Copyright (C) 1985, 1992, 1994, 2001-2019 Free Software Foundation,
 ;; Inc.
@@ -104,10 +104,9 @@ You can thus get the full benefit of adaptive filling
  (see the variable `adaptive-fill-mode').
 \\{text-mode-map}
 Turning on Text mode runs the normal hook `text-mode-hook'."
-  (set (make-local-variable 'text-mode-variant) t)
-  (set (make-local-variable 'require-final-newline)
-       mode-require-final-newline)
-  (set (make-local-variable 'indent-line-function) 'indent-relative))
+  (setq-local text-mode-variant t)
+  (setq-local require-final-newline mode-require-final-newline)
+  (setq-local indent-line-function #'indent-relative))
 
 (define-derived-mode paragraph-indent-text-mode text-mode "Parindent"
   "Major mode for editing text, with leading spaces starting a paragraph.
@@ -131,14 +130,12 @@ Turning on Paragraph-Indent minor mode runs the normal hook
   :initial-value nil
   ;; Change the definition of a paragraph start.
   (let ((ps-re "[ \t\n\f]\\|"))
-    (if (eq t (compare-strings ps-re nil nil
-                               paragraph-start nil (length ps-re)))
+    (if (string-prefix-p ps-re paragraph-start)
         (if (not paragraph-indent-minor-mode)
-            (set (make-local-variable 'paragraph-start)
-                 (substring paragraph-start (length ps-re))))
+            (setq-local paragraph-start
+                        (substring paragraph-start (length ps-re))))
       (if paragraph-indent-minor-mode
-          (set (make-local-variable 'paragraph-start)
-               (concat ps-re paragraph-start)))))
+          (setq-local paragraph-start (concat ps-re paragraph-start)))))
   ;; Change the indentation function.
   (if paragraph-indent-minor-mode
       (add-function :override (local 'indent-line-function)
@@ -154,7 +151,7 @@ Turning on Paragraph-Indent minor mode runs the normal hook
 (defun text-mode-hook-identify ()
   "Mark that this mode has run `text-mode-hook'.
 This is how `toggle-text-mode-auto-fill' knows which buffers to operate on."
-  (set (make-local-variable 'text-mode-variant) t))
+  (setq-local text-mode-variant t))
 
 (defun toggle-text-mode-auto-fill ()
   "Toggle whether to use Auto Fill in Text mode and related modes.
@@ -163,8 +160,8 @@ both existing buffers and buffers that you subsequently create."
   (interactive)
   (let ((enable-mode (not (memq 'turn-on-auto-fill text-mode-hook))))
     (if enable-mode
-        (add-hook 'text-mode-hook 'turn-on-auto-fill)
-      (remove-hook 'text-mode-hook 'turn-on-auto-fill))
+        (add-hook 'text-mode-hook #'turn-on-auto-fill)
+      (remove-hook 'text-mode-hook #'turn-on-auto-fill))
     (dolist (buffer (buffer-list))
       (with-current-buffer buffer
         (if (or (derived-mode-p 'text-mode) text-mode-variant)
@@ -214,15 +211,14 @@ The argument NLINES says how many lines to center."
   (while (not (eq nlines 0))
     (save-excursion
       (let ((lm (current-left-margin))
-            line-length)
+            space)
         (beginning-of-line)
         (delete-horizontal-space)
         (end-of-line)
         (delete-horizontal-space)
-        (setq line-length (current-column))
-        (if (> (- fill-column lm line-length) 0)
-            (indent-line-to
-             (+ lm (/ (- fill-column lm line-length) 2))))))
+        (setq space (- fill-column lm (current-column)))
+        (if (> space 0)
+            (indent-line-to (+ lm (/ space 2))))))
     (cond ((null nlines)
            (setq nlines 0))
           ((> nlines 0)