bug#14187: [PATCH] Pretty-print long values in custom variables

[Adam Spiers <emacs@adamspiers.org>]

* cus-edit.el (custom-save-variables): When a custom value is over 60
characters long, insert it using indent-pp-sexp so that the value is
more legible through being split over multiple lines.  This is
particularly useful when `custom-file' is tracked by a version control
system, since then the diffs become much more manageable.
---
 lisp/cus-edit.el | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/lisp/cus-edit.el b/lisp/cus-edit.el
index d19e2de..8a018cb 100644
--- a/lisp/cus-edit.el
+++ b/lisp/cus-edit.el
@@ -4529,7 +4529,15 @@ This function does not save the buffer."
 	    (princ " '(")
 	    (prin1 symbol)
 	    (princ " ")
-	    (prin1 (car value))
+	    (let ((val (prin1-to-string (car value))))
+	      (if (< (length val) 60)
+		  (insert val)
+		(newline-and-indent)
+		(let ((beginning-of-val (point)))
+		  (insert val)
+		  (save-excursion
+		    (goto-char beginning-of-val)
+		    (indent-pp-sexp 1)))))
 	    (when (or now requests comment)
 	      (princ " ")
 	      (prin1 now)
-- 
1.8.2.1.347.gbef22ca