From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "B.V. Raghav" Newsgroups: gmane.emacs.help Subject: Re: Skeleton angle brackets '<' and '>' Date: Sat, 09 Jan 2016 00:03:45 +0530 Message-ID: <8737u72a5y.fsf@think.bvr.lan> References: NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1452278063 9377 80.91.229.3 (8 Jan 2016 18:34:23 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 8 Jan 2016 18:34:23 +0000 (UTC) Cc: help-gnu-emacs@gnu.org To: Alan Mackenzie Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Fri Jan 08 19:34:14 2016 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1aHbrZ-0007EK-EY for geh-help-gnu-emacs@m.gmane.org; Fri, 08 Jan 2016 19:34:13 +0100 Original-Received: from localhost ([::1]:37662 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aHbrY-00044M-Md for geh-help-gnu-emacs@m.gmane.org; Fri, 08 Jan 2016 13:34:12 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:39372) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aHbrO-000445-3v for help-gnu-emacs@gnu.org; Fri, 08 Jan 2016 13:34:03 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aHbrK-0003u1-6m for help-gnu-emacs@gnu.org; Fri, 08 Jan 2016 13:34:02 -0500 Original-Received: from mail2.iitk.ac.in ([202.3.77.186]:53033) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aHbrJ-0003sj-NO for help-gnu-emacs@gnu.org; Fri, 08 Jan 2016 13:33:58 -0500 Original-Received: from smtp.cc.iitk.ac.in (smtp.cc.iitk.ac.in [172.31.1.22]) by mail2.iitk.ac.in (Postfix) with ESMTP id E08F11000129; Sat, 9 Jan 2016 00:03:45 +0530 (IST) Original-Received: from think (unknown [172.20.220.29]) (Authenticated sender: bvraghav) by smtp.cc.iitk.ac.in (Postfix) with ESMTPA id D707C48; Sat, 9 Jan 2016 00:03:45 +0530 (IST) In-Reply-To: (Alan Mackenzie's message of "Wed, 6 Jan 2016 17:59:39 +0000 (UTC)") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6.x X-Received-From: 202.3.77.186 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:108659 Archived-At: Alan Mackenzie writes: > B.V. Raghav wrote: >> Hi, > >> There are smart tools for the purpose, but I prefer to stick to the old >> school for auto pairing. > >> Electric Pair mode and Skeleton pair, like this: >> (electric-pair-mode t) >> (setq skeleton-pair t) > >> While in the c++ mode, (hopefully true for all c-modes) >> I am able to successfully pair (), {}, and [], with a single key press, >> i.e. of the preceding character of the pair. > >> I also want to pair the angle brackets, i.e. `<' and `>' characters. > > Be careful what you want! Do you also want automatically to pair up > "less than" with "greater than"? It could get pretty tedious if, every > time you wanted to write "i < 10", you got "i <>", forcing you to delete > the ">" before writing in the "10". > > This overloading of < and > with two meanings (actually, three when you > count "#include ", but that causes few problems) causes great > difficulties for C++ Mode. Only after extensive analysis can the mode > determine that a < and a > are a pair of template delimiters, and even > then, can't do it with 100% certainty. > > For example, how many parameters are passed to foo in the following: > > foo (a < b, c > d); Now I remember the problem. It was there when I simillarly, had to pass a templated type as argumentn to preprocessors using typedefs. This thread helped me recall. http://stackoverflow.com/a/7304772/4366367 One of the examples, that extensively uses typedefs to avoid this problem is Boost.Exceptions uses #define , template<> and overloading operator << --- extensively http://www.boost.org/doc/libs/1_60_0/libs/exception/doc/boost-exception.html > > ? It might be a function call with two relational expressions, it might > be a declaration with the single parameter d of templated type a . > Such was the wisdom of C++'s designers. > > When it is determined there is a pair of delimiters, they are marked as > such with syntax-table text properties, but this marking is always done > on both delimiters at once. > > In short, there is little chance of ever being able to insert angle > brackets as a pair in C++ Mode. Sorry! > >> The documentation for the variable sekeleton-pair-alist says, > >> [...] >> Each alist element, which looks like (ELEMENT ...), is passed to >> `skeleton-insert' with no interactor. Variable `str' does nothing. > >> Elements might be (?` ?` _ "''"), (?\( ? _ ")") or(?{ \n > _ \n ?} >). >> [...] > >> I am sorry to say, I cant make a head or tail of this cryptic value >> suggested for the variable. > > Sorry to say this, but neither can I. I don't know what an "interactor" > is, variable `str' is obscure, and it is totally unclear what the various > example elements might mean. > >> Help solicited. > > Can I suggest you submit a bug report for this dreadful doc string? > >> Thanks, >> r >> -- >> (B.V. Raghav) -- (B.V. Raghav)