When I set the following in a mode
(https://github.com/TLINDEN/config-general-mode):

   (setq-local hippie-expand-only-buffers '(config-general-mode))

and have a .c file with c-mode open, and a file with config-general
mode, then 'try-expand-dabbrev-all-buffers expands from the .c file
as well, which is not what I expected.

It turns out, that the function (and all other try-expand-* functions
as well!) loops over all buffers in a while loop with 'set-buffer,
which then uses variables local for that *current* buffer or the
global ones, but not buffer-local variables from the original buffer,
from where the function was invoked. Since 'hippie-expand-only-buffers
is nil globally and not configured locally in c-mode (in my case),
it uses dabbrevs found in that file and thus ignores my buffer-local
setting.

The attached patch fixes this behavior by working on copies of the
relevant variables. It fixes 'try-expand-dabbrev-all-buffers only,
since I am not sure if the patch would be required by the other try
functions as well.



best regards,
Tom


In GNU Emacs 24.5.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.8)
 of 2015-06-15 on nubic
Windowing system distributor `The X.Org Foundation', version
11.0.11501000
System Description: Ubuntu 14.04.4 LTS

Configured using:
 `configure --with-xpm=no --with-jpeg=no --with-gif=no --with-tiff=no'

Important settings:
  value of $LC_MONETARY: de_DE.UTF-8
  value of $LC_NUMERIC: de_DE.UTF-8
  value of $LC_TIME: de_DE.UTF-8
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  ido-everywhere: t
  show-paren-mode: t
  tooltip-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Making completion list... [2 times]
current-kill: Kill ring is empty

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util
help-fns mail-prsvr mail-utils help-mode easymenu ido edmacro kmacro
cl-loaddefs cl-lib paren time-date tooltip electric uniquify ediff-hook
vc-hooks lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list newcomment lisp-mode prog-mode register
page menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock
font-lock syntax facemenu font-core frame cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese hebrew
greek romanian slovak czech european ethiopic indian cyrillic chinese
case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer nadvice
loaddefs button faces cus-face macroexp files text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process dbusbind
gfilenotify dynamic-setting system-font-setting font-render-setting
move-toolbar gtk x-toolkit x multi-tty emacs
)

Memory information:
((conses 16 87889 34583)
 (symbols 48 18533 1)
 (miscs 40 52 172)
 (strings 32 18602 28208)
 (string-bytes 1 447810)
 (vectors 16 9991)
 (vector-slots 8 397326 31713)
 (floats 8 76 172)
 (intervals 56 233 101)
 (buffers 960 12)
 (heap 1024 29194 3379))
)