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Re: view-read-only causes read-write

From: Kevin Rodgers
Subject: Re: view-read-only causes read-write
Date: Thu, 17 Apr 2003 11:10:29 -0600
User-agent: Mozilla/5.0 (X11; U; SunOS i86pc; en-US; rv: Gecko/20020406 Netscape6/6.2.2

Dan Jacobson wrote:

I did
$ emacs --no-site-file -q -nw -eval '
  (and(setq view-read-only t) (describe-variable (quote

1. Ok, the help buffer says View mode in the modeline, but how about
   turning on the -%%- marker in the modeline?

Setting that variable is not the right way to turn on View mode.  Setting
any variable is never the right the right way to turn on a mode.  Use the
mode's function.

2. Hey, real view-mode doesn't let me eat text with C-k etc, and then
   you can't repair the damage with undo because no undo record is
   kept for that buffer.

If you want the buffer in View mode, run the view-mode function.

3. OK, trying again without messing first with view-read-only
   gives what one expects.

   Do I smell someone toggling read-only once too much?

No.  You don't understand that the variable is read to indicate to the user
that view mode is on, and that the view-mode function is used to invoke the

4. view-read-only's docstring: "*Non-nil means buffers visiting files
   read-only, do it in view mode." (P.S. I assume the "*" means
   "Chef's choice".)

   OK, but what about read-only buffers not visiting files? Obviously
   you are over affecting those and at the same time not mentioning them.

M-x pick-nit

P.S. I am no lisp pro but above I had to use an "(and ...)" or else
only one sexp was used, without any warning to the user.

Of course.  Symbolic expressions are well-defined: (function arg ...).
In order to evaluate multiple sexps in sequence, use (progn ...) or multiple
--eval command line options.

PSS, while we are here, let's examine this docstring:
  toggle-read-only is an interactive compiled Lisp function in `files'.
  (toggle-read-only &optional ARG)

  Change whether this buffer is visiting its file read-only.
  With arg, set read-only iff arg is positive.

Ok, but it doesn't say what will happen if you give it a non positive
arg.  One can't just assume "common sense".  E.g. me, any common sense
and I wouldn't be hanging around this pop stand.

"iff" means "if and only if", which is a well-defined logical operator.  It
means that if arg is not positive, unset read-only.

  If visiting file read-only and `view-read-only' is non-nil, enter view mode.

Hold on a second. We came here to toggle-read-only and like wham, we
are sent into view mode. It's like I do "chmod -w file" and wham, "more
file" is invoked as a free bonus.  What if I am a batch job? Anyway,
docsting looks bad. Didn't check the code.

Then do (setq read-only t) instead of (toggle-read-only 1) to avoid the side


<a href="mailto:&lt;kevin.rodgers&#64;ihs.com&gt;";>Kevin Rodgers</a>

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