bug#8368: 24.0.50; "temp" means "help" - rename or at least document

[Drew Adams]

> From: Stefan Monnier Sent: Saturday, September 10, 2011 9:58 PM
>
Lars> There's been no response in two months.
Lars> I think the following is a bug:
Lars> ;; This makes `with-output-to-temp-buffer' buffers use `help-mode'.
Lars> (add-hook 'temp-buffer-setup-hook 'help-mode-setup)
Lars> (add-hook 'temp-buffer-show-hook 'help-mode-finish)
Lars> Would removing these be a good idea?
> 
> Not at this stage of the development, no.

So now it's been over a year since the bug was filed.

Can't the help mode code add those hooks only for the use of *Help* and other
help-mode buffers?  Why should all uses of `with-output-to-temp-buffer' end up
running those hook functions that are, after all, specific to help mode?

Can we please move forward on fixing this bug?

There is lots of stuff in a "temp" buffer now that has nothing to do with a
temporary buffer.

emacs -Q
(setq debug-on-error t)
(defun foo ()
  "..."
  (with-output-to-temp-buffer "*TEMP*"
    (princ "FOOOOO\n-----\n\n")))
(foo)
C-x b *TEMP*
TAB

Debugger entered--Lisp error: (error "No buttons!")
  signal(error ("No buttons!"))
  error("No buttons!")
  forward-button(1 1 1)
  call-interactively(forward-button nil nil)

No f___ing buttons?  WTF?  Who cares?

Look at all the keys bound now in a "temporary" buffer (below).  How many of
them have to do with a temporary display of something other than outright
*Help*?

The only keys I can think of that might generally make sense for a temporary
buffer mode are SPC, DEL, <, >, ?, h, q, maybe z (but why was `z' chosen to
kill?), maybe the digits and -, and maybe (if `revert-buffer-function' says so)
g.

All of the special help link and navigation commands should be reserved for a
help mode that is _derived_ from a (minimal) temporary buffer mode.

While waiting for that, users have to do something like this, just to get rid of
the *Help*-imposed stuff:

(defmacro with-output-to-plain-temp-buffer (buf &rest body)
  "Like `with-output-to-temp-buffer', but with no *Help* navigation stuff."
  `(unwind-protect
    (progn
      (remove-hook 'temp-buffer-setup-hook 'help-mode-setup)
      (remove-hook 'temp-buffer-show-hook  'help-mode-finish)
      (with-output-to-temp-buffer ,buf ,@body))
    (add-hook 'temp-buffer-setup-hook 'help-mode-setup)
    (add-hook 'temp-buffer-show-hook  'help-mode-finish)))

It makes no more sense for *Help* to have co-opted temporary buffer display than
it would have made for Info to have co-opted it.  Dunno how we ever went down
this road.

key             binding
---             -------

C-c             Prefix Command
TAB             forward-button
RET             help-follow
ESC             Prefix Command
SPC             scroll-up-command
-               negative-argument
0 .. 9  digit-argument
<               beginning-of-buffer
>               end-of-buffer
?               describe-mode
g               revert-buffer
h               describe-mode
q               quit-window
z               kill-this-buffer
DEL             scroll-down-command
<backtab>       backward-button
<mouse-2>       help-follow-mouse
<remap> Prefix Command

C-c C-b help-go-back
C-c C-c help-follow-symbol
C-c C-f help-go-forward

M-TAB           backward-button