From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Alan Mackenzie Newsgroups: gmane.emacs.devel Subject: Re: Supporting tabs for indentation, spaces for alignment Date: Thu, 11 Apr 2019 09:02:23 +0000 Message-ID: <20190411090223.GA5183@ACM> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="136098"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Mutt/1.10.1 (2018-07-13) Cc: emacs-devel@gnu.org To: Ergus Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Thu Apr 11 11:03:19 2019 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hEVc6-000ZFX-9P for ged-emacs-devel@m.gmane.org; Thu, 11 Apr 2019 11:03:18 +0200 Original-Received: from localhost ([127.0.0.1]:44705 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hEVc5-0000nT-6U for ged-emacs-devel@m.gmane.org; Thu, 11 Apr 2019 05:03:17 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:37193) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hEVbJ-0000n6-0Z for emacs-devel@gnu.org; Thu, 11 Apr 2019 05:02:30 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hEVbH-0003aR-DI for emacs-devel@gnu.org; Thu, 11 Apr 2019 05:02:28 -0400 Original-Received: from colin.muc.de ([193.149.48.1]:18413 helo=mail.muc.de) by eggs.gnu.org with smtp (Exim 4.71) (envelope-from ) id 1hEVbH-0003YK-1s for emacs-devel@gnu.org; Thu, 11 Apr 2019 05:02:27 -0400 Original-Received: (qmail 61764 invoked by uid 3782); 11 Apr 2019 09:02:24 -0000 Original-Received: from acm.muc.de (p4FE15DBC.dip0.t-ipconnect.de [79.225.93.188]) by colin.muc.de (tmda-ofmipd) with ESMTP; Thu, 11 Apr 2019 11:02:23 +0200 Original-Received: (qmail 5841 invoked by uid 1000); 11 Apr 2019 09:02:23 -0000 Content-Disposition: inline X-Delivery-Agent: TMDA/1.1.12 (Macallan) X-Primary-Address: acm@muc.de X-detected-operating-system: by eggs.gnu.org: FreeBSD 9.x [fuzzy] X-Received-From: 193.149.48.1 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:235273 Archived-At: Hello again, Ergus. You were asking in your post Subject: Re: C style alist question? for a way of indenting CC Mode modes with "tabs for indentation and spaces for alignment." The topic has come up before, and I answered back in 2008 with the following post to the OP and bug-cc-mode@gnu.org. It's a bit wordy, I admit, but does provide a way of getting what you're asking for. I admit not having tried it out recently. -- Alan Mackenzie (Nuremberg, Germany). ----- Forwarded message from Alan Mackenzie ----- X-Spam-Checker-Version: SpamAssassin 3.2.0 (2007-05-01) on colin2.muc.de X-Spam-Level: X-Spam-Status: No, score=0.1 required=5.0 tests=AWL,BAYES_50 autolearn=no version=3.2.0 Date: Fri, 11 Apr 2008 20:31:42 +0000 To: Mike Sullivan Subject: Re: Supporting tabs for indentation, spaces for alignment X-Delivery-Agent: TMDA/1.1.5 (Fettercairn) From: Alan Mackenzie X-Primary-Address: acm@muc.de X-detected-kernel: by monty-python.gnu.org: FreeBSD 4.6-4.9 Cc: bug-cc-mode@gnu.org X-BeenThere: cc-mode-help@lists.sourceforge.net X-Mailman-Version: 2.1.8 Reply-To: bug-cc-mode@gnu.org List-Id: "Bug reports, feature requests, and general talk about CC Mode." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi, Mike, Sorry it's taken me so long to answer. On Wed, Jan 09, 2008 at 02:04:40AM -0600, Mike Sullivan wrote: > Currently, cc-mode offers no simple way to use tabs for indentation, > but spaces for alignment (as described many places on the web, > including http://wiki.chad.org/wiki?IndentationUsingTabs). Is there > any chance that this will be added as a feature in a future version? OK: Here's what I think that page means. Supposing your tab-width is 8, in { if (a really long conditional that won't fit onto one line) { .... .... } } , you want (I think), tabs here: tttttttt , yet spaces here: .... If your tab-width were 2, you'd want to see this: { if (a really long conditional that won't fit onto one line) { .... .... } } , with tabs here: tt , and spaces here: .... . Currently, assuming indent-tabs-mode is set, with a sufficiently large tab-width (say, 8), this is what you'll get, but with a smaller tab-width (2), the four spaces will be replaced by two tabs, not what you want. No, there are no plans for putting such a feature into CC Mode at the moment. One could opine that the opinions on that web page are somewhat opinionated, capable of triggering religious wars. ;-) My own view is that that indentation strategy would be a right royal pain, unless it somehow got enforced 100% by the project's management and _every_ editor in use supported it. To implement the idea "properly" in CC Mode would entail a non-trivial amount of work. However, this is the sort of thing that seems tailor-made for c-special-indent-hook (see page "Other Indentation" in the CC Mode manual), and shows just how flexible Emacs (in general) and CC Mode (in particular) are, and just how superior they are to lesser editors. ;-) I've written a quick hack, to give you an idea how this sort of thing could work. Here's the source file I tried it on, _without_ tabs here (it goes more easily into an email that way), with c-basic-offset = 3: int foo (char a, char b, char c, char d, char e, char f, char g) { if (a = 'a' && b = 'b' && c = 'c') { print "hi!\n" ; return 0 ; } return 1 ; } As a quick tip, to _see_ tabs in a buffer, do M-x hi-lock-mode, then C-x w h. On being prompted for a regexp just do C-q , then select some highlighting face. OK, here's the hack: (defun ms-space-for-alignment () "Make the current line use tabs for indentation and spaces for alignment. It is intended to be called from the hook `c-special-indent-hook'. It assumes that `indent-tabs-mode' is non-nil and probably assumes that `c-basic-offset' is the same as `tab-width'." (save-excursion (let* ((indent-pos (progn (back-to-indentation) (point))) (indent-col (current-column)) (syn-elt (car c-syntactic-context)) (syn-sym (c-langelem-sym syn-elt))) (when (memq syn-sym '(arglist-cont-nonempty)) ;; <============== (let* ((syn-anchor (c-langelem-pos syn-elt)) (anchor-col (progn (goto-char syn-anchor) (back-to-indentation) (current-column))) num-tabs) ;; (goto-char indent-pos) (delete-horizontal-space) (insert-char ?\t (/ anchor-col tab-width)) (insert-char ?\ (- indent-col (current-column)))))))) To enable it, do this: M-: (setq indent-tabs-mode t) M-: (setq tab-width 3) M-: (setq c-basic-offset tab-width) (add-hook 'c-special-indent-hook 'ms-space-for-alignment nil t) If you were to develop this hack into fully working code, I would be willing to put it into the next full version of CC Mode (subject to the customary copyright assignment to the FSF, which we all have to do). > Thanks, Mike Sullivan Happy hacking! -- Alan Mackenzie (Nuremberg, Germany). ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone ----- End forwarded message -----