Subject: Re: bug#32896: 27.0.50; wishlist: Delete matching pairs

From: Juri Linkov <[email-masked]>
Date: Wed, 17 Oct 2018 02:00:14 +0300

>> Fortunately, Emacs already has such a command named ‘delete-pair’:
>> it deletes the parens around the let function as in your first
>> example as well as the quotes in your second example.  It makes
>> sense to bind this command to e.g. ‘C-x M-(’ to be the inverse of
>> ‘M-(’ (insert-pair)
>
> Yay! I didn't know about that command (and I really did search before
> reporting this bug, no idea how I missed it!). It doesn't work backward
> though as far as I can tell:
>
> (let (message "%s" "foobar")|)

With a simple twist in the patch attached, it will be able to work backward
with M-- M-x delete-pair, i.e. with a negative prefix argument.

diff --git a/lisp/emacs-lisp/lisp.el b/lisp/emacs-lisp/lisp.el
index 5a89923f8f..fd6018988e 100644
--- a/lisp/emacs-lisp/lisp.el
+++ b/lisp/emacs-lisp/lisp.el
@@ -723,11 +723,12 @@ insert-parentheses
   (interactive "P")
   (insert-pair arg ?\( ?\)))
 
-(defun delete-pair ()
+(defun delete-pair (&optional arg)
   "Delete a pair of characters enclosing the sexp that follows point."
-  (interactive)
-  (save-excursion (forward-sexp 1) (delete-char -1))
-  (delete-char 1))
+  (interactive "p")
+  (unless arg (setq arg 1))
+  (save-excursion (forward-sexp arg) (delete-char (if (> arg 0) -1 1)))
+  (delete-char (if (> arg 0) 1 -1)))
 
 (defun raise-sexp (&optional arg)
   "Raise ARG sexps higher up the tree."