bug#13032: 24.3.50; Request: Provide a `delete-duplicate-lines' command

[Dani Moncayo <dmoncayo@gmail.com>]

Severity: wishlist

Recent versions of MS-Excel and also LibreOffice's Calc have a feature
that I find very useful: the ability of remove duplicate lines from a
given list (range).  I think it would be worth to add such a feature
to Emacs.

That is: provide a function `delete-duplicate-lines' (or some such)
that removes all duplicate lines in the active region and prints in
the echo area a message like "Duplicate lines removed: <n>".

TIA.

PS: There has been some discussion about this in this thread:
http://lists.gnu.org/archive/html/help-gnu-emacs/2012-11/msg00417.html.
 Jambunathan K provided a possible implementation, but it lacks the
message in the echo area (which I think is important).


In GNU Emacs 24.3.50.1 (i386-mingw-nt6.1.7601)
 of 2012-11-28 on MS-W7-DANI
Bzr revision: 111021 jay.p.belanger@gmail.com-20121128045113-o6xvwncuryx8al3u
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --with-gcc (4.7) --no-opt --enable-checking --cflags
 -Ic:/emacs/libs/libXpm-3.5.10/include -Ic:/emacs/libs/libXpm-3.5.10/src
 -Ic:/emacs/libs/libpng-1.2.37-lib/include -Ic:/emacs/libs/zlib-1.2.5
 -Ic:/emacs/libs/giflib-4.1.4-1-lib/include
 -Ic:/emacs/libs/jpeg-6b-4-lib/include
 -Ic:/emacs/libs/tiff-3.8.2-1-lib/include
 -Ic:/emacs/libs/libxml2-2.7.8-w32-bin/include/libxml2
 -Ic:/emacs/libs/gnutls-3.0.9-w32-bin/include
 -Ic:/emacs/libs/libiconv-1.9.2-1-lib/include'

Important settings:
  value of $LANG: ENU
  locale-coding-system: cp1252
  default enable-multibyte-characters: t

-- 
Dani Moncayo