bug#14591: New keyword :local for defcustom

[Juanma Barranquero <lekktu@gmail.com>]

On Wed, Jun 12, 2013 at 7:27 PM, Glenn Morris <rgm@gnu.org> wrote:

> (Do you ever
> want to make something permanent-local but not buffer-local?)

69 variables are so marked on lisp/**

Of these, 8 are really minor modes (so they are always used as buffer-local).

2 are defcustoms:

  2C-separator
  backup-by-copying-when-mismatch

The rest:

  archive-superior-buffer
  backup-inhibited
  buffer-auto-save-file-format
  buffer-file-format
  comint-input-autoexpand
  comint-input-filter-functions
  comint-input-ring
  comint-input-ring-index
  comint-move-point-for-output
  comint-output-filter-functions
  comint-preoutput-filter-functions
  comint-ptyp
  comint-save-input-ring-index
  comint-scroll-show-maximum-output
  comint-scroll-to-bottom-on-input
  custom-local-buffer
  cvs-buffer
  cvs-edit-log-files
  enable-character-translation
  epa-file-encrypt-to
  find-file-literally
  gud-find-file
  gud-marker-filter
  input-method-function
  plstore-encoded
  plstore-encrypt-to
  rcirc-urls
  revert-buffer-function
  revert-buffer-insert-file-contents-function
  rmail-buffer
  rmail-current-message
  rmail-deleted-vector
  rmail-inbox-list
  rmail-last-regexp
  rmail-message-vector
  rmail-mime-decoded
  rmail-msgref-vector
  rmail-old-headers
  rmail-old-pruned
  rmail-overlay-list
  rmail-seriously-modified
  rmail-summary-buffer
  rmail-summary-overlay
  rmail-summary-vector
  rmail-total-messages
  rmail-was-converted
  tar-superior-buffer
  tar-superior-descriptor
  term-input-autoexpand
  term-input-filter-functions
  term-input-ring
  term-input-ring-index
  term-ptyp
  term-scroll-show-maximum-output
  term-scroll-to-bottom-on-output
  vc-log-view-type
  vc-parent-buffer
  vc-parent-buffer-name
  write-file-functions

Of course, some (perhaps most) of these are made buffer-local when
used. But there are a few which are not, in a not-making-sense way.
One of them that I already mentioned is revert-buffer-function, but
backup-inhibited is even more ridiculous, because its docstring says:

  This variable is intended for use by making it local to a buffer.
  But it is local only if you make it local.

So we have a variable which is permanent local, *intended* to be used
as buffer-local, yet very explicitly and (apparently) purposefully not
made automatically buffer-local.

Color me puzzled,

   Juanma