Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!ucsd!pacbell.com!decwrl!hayes.fai.alaska.edu!accuvax.nwu.edu!mmdf
From: lynch@aristotle.ils.nwu.edu (Richard Lynch)
Newsgroups: comp.lang.lisp
Subject: Matching Parens (was Virtues of LISP Syntax?)
Message-ID: <12558@accuvax.nwu.edu>
Date: 25 Sep 90 22:15:43 GMT
Sender: mmdf@accuvax.nwu.edu
Lines: 61

I can read LISP code just fine if "standard" parenthesis rules are used.
BUT, when it comes to debugging code known to be faulty, I really hate to try
and figure out which parenthesis the ones at the end of a line are coding.
And it's not enough to assume that the code is lined up correctly (even by
the editors that supposedly line it up for you.)
That's why I always follow these rules:

A closing parenthesis can only appear:
  A.  In the same line as the open parenthesis.
  B.  In the same column as the open parenthesis.

The indentation for arguments on lines below the function is 2 spaces.  Always.

Thus, my code looks like this:

(defun insert-menu (menu &optional (place nil))
"Inserts menu at place in the menubar.  If place is a menu, the new menu goes
after it.  If place is an integer, the menu goes in that ordinal position."
  (let ((need-update (installed-p)))
    (if place
      (let* ((old-menus (menus))
             (len (length old-menus))
            )
        (when (isa-p place *menu*)
          (let ((pos (position place old-menus)))
            (if pos
              (setq place (1+ pos))
              (setq place (1+ len))
        ) ) )
        (if (integerp place)
          (progn
            (setq place (max 0 place))
            (setq place (min place (1+ len)))
            (if (= place (1+ len))
              (add-menu menu)
              (set-menus (nconc (subseq old-menus 0 place)
                                (list menu)
                                (subseq old-menus  place len)
          ) ) )          )
          (cerror "Adding ~S to end of menubar..."
                  "Invalid place specifier ~S for insert-menu.~%~
                   place must be an integer or menu." place
                  (add-menu menu)
          )
      ) )
      (add-menu menu)
    )
    (if need-update (set-menubar (menus)))
) )

Actually, before you flame me, I am aware that on lines that have just
right parens, they are in reverse order and thus my rules are incorrectly
stated.  But I consider them "isomorphic" in some sense.

I hardly ever have parenthesis problems, and when I do, I find the error very
quickly.
The expense of a lot of lines with just right parens is worth the benifit of
minimal debugging time to me.
Anyone else use this, or am I all alone here?

"TANSTAAFL" Rich lynch@aristotle.ils.nwu.edu