From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 86744 invoked by alias); 9 Nov 2016 15:27:19 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 86732 invoked by uid 89); 9 Nov 2016 15:27:18 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.8 required=5.0 tests=BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=settle, _not_, personal X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 09 Nov 2016 15:27:08 +0000 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 324C167AF2; Wed, 9 Nov 2016 15:27:07 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uA9FR5Zp019652; Wed, 9 Nov 2016 10:27:06 -0500 Subject: Re: [PATCH] gdb: Use vector::emplace_back To: John Baldwin , gdb-patches@sourceware.org References: <1478651991-5083-1-git-send-email-palves@redhat.com> <75ff8113-cd29-c76d-030b-a296d23d13bb@redhat.com> <1575403.749fUSKQim@ralph.baldwin.cx> Cc: Yao Qi From: Pedro Alves Message-ID: <79425cad-160f-d1a2-3275-29605db7a7cb@redhat.com> Date: Wed, 09 Nov 2016 15:27:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <1575403.749fUSKQim@ralph.baldwin.cx> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit X-SW-Source: 2016-11/txt/msg00221.txt.bz2 On 11/09/2016 02:48 PM, John Baldwin wrote: > On Wednesday, November 09, 2016 12:55:52 PM Pedro Alves wrote: >> On 11/09/2016 12:42 PM, Yao Qi wrote: >> >>> I know leading underscore is used in some projects, so I want to know >>> is it a C++ code standard that we use trailing underscore in this case or >>> it is your personal coding habit. It is the latter. >> >> ... >> >>> Since the trailing underscore usage like this is not mentioned in C++ >>> code standard, people are free to use or not to use it. I don't have >>> a preference on that. >> >> OK. I may ask a couple gcc people for their preference and see about >> adding it to the docs. Each detail in the standard is based on >> someone's personal preference that had sufficient following/agreement, >> after all. :-) > > If the goal is to support -Wshadow then it would be nice to settle on a style > so it is consistent across the tree. It's not really about -Wshadow. In C++, in order to use a member initializer, like in: cmdarg (cmdarg_kind type_, char *string_) : type (type_), string (string_) {} The parameter names really must be different from the struct's elements. This: cmdarg (cmdarg_kind type, char *string) : this->type (type), this->string (string) {} is not valid C++ and does _not_ compile: src/gdb/main.c:450:7: error: expected identifier before ‘this’ : this->type (type_), this->string (string_) ^ This instead would work: cmdarg (cmdarg_kind type, char *string) { this->type = type; this->string = string; } However, using member initializer lists is a better default, because there are cases where the above using assignment wouldn't work or wouldn't be as efficient. E.g., in case the element being constructed has a heavy constructor, does not have a default constructor at all, or doesn't have an assignment operator. You can find more here: http://stackoverflow.com/questions/926752/why-should-i-prefer-to-use-member-initialization-list Thanks, Pedro Alves