From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Davis Herring" Newsgroups: gmane.emacs.devel Subject: Re: Is (provide 'foo) at the start good or bad? Date: Fri, 12 Jun 2009 16:00:03 -0700 (PDT) Message-ID: <49293.130.55.118.19.1244847603.squirrel@webmail.lanl.gov> References: <21glws7jx732.fsf@gmail.com> <87r5xqw0s8.fsf@uwakimon.sk.tsukuba.ac.jp> Reply-To: herring@lanl.gov NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain;charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1244847626 24697 80.91.229.12 (12 Jun 2009 23:00:26 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 12 Jun 2009 23:00:26 +0000 (UTC) Cc: Leo , emacs-devel@gnu.org To: "Stephen J. Turnbull" Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Jun 13 01:00:22 2009 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1MFFjS-0002wa-2Z for ged-emacs-devel@m.gmane.org; Sat, 13 Jun 2009 01:00:22 +0200 Original-Received: from localhost ([127.0.0.1]:43868 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MFFjR-0000JC-I7 for ged-emacs-devel@m.gmane.org; Fri, 12 Jun 2009 19:00:21 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MFFjL-0000H0-Px for emacs-devel@gnu.org; Fri, 12 Jun 2009 19:00:15 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MFFjG-0000Ds-Dl for emacs-devel@gnu.org; Fri, 12 Jun 2009 19:00:14 -0400 Original-Received: from [199.232.76.173] (port=46975 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MFFjG-0000Dk-A5 for emacs-devel@gnu.org; Fri, 12 Jun 2009 19:00:10 -0400 Original-Received: from proofpoint1.lanl.gov ([204.121.3.25]:42733) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1MFFjF-0007Id-Np for emacs-devel@gnu.org; Fri, 12 Jun 2009 19:00:10 -0400 Original-Received: from mailrelay1.lanl.gov (mailrelay1.lanl.gov [128.165.4.101]) by proofpoint1.lanl.gov (8.14.3/8.14.3) with ESMTP id n5CN03Vf029968; Fri, 12 Jun 2009 17:00:03 -0600 Original-Received: from localhost (localhost.localdomain [127.0.0.1]) by mailrelay1.lanl.gov (Postfix) with ESMTP id 66105160198; Fri, 12 Jun 2009 17:00:03 -0600 (MDT) X-NIE-2-Virus-Scanner: amavisd-new at mailrelay1.lanl.gov Original-Received: from webmail1.lanl.gov (webmail1.lanl.gov [128.165.4.106]) by mailrelay1.lanl.gov (Postfix) with ESMTP id 528A8160195; Fri, 12 Jun 2009 17:00:03 -0600 (MDT) Original-Received: by webmail1.lanl.gov (Postfix, from userid 48) id 4FC161518033; Fri, 12 Jun 2009 17:00:03 -0600 (MDT) Original-Received: from 130.55.118.19 (SquirrelMail authenticated user 196434) by webmail.lanl.gov with HTTP; Fri, 12 Jun 2009 16:00:03 -0700 (PDT) In-Reply-To: <87r5xqw0s8.fsf@uwakimon.sk.tsukuba.ac.jp> User-Agent: SquirrelMail/1.4.8-5.7.lanl1 X-Priority: 3 (Normal) Importance: Normal X-Proofpoint-Virus-Version: vendor=fsecure engine=1.12.8161:2.4.5, 1.2.40, 4.0.166 definitions=2009-06-12_08:2009-06-01, 2009-06-12, 2009-06-12 signatures=0 X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.6, seldom 2.4 (older, 4) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:111465 Archived-At: > Putting the provide form at the beginning allows mutually recursive > requires to succeed. If you have two files which require each other, why do they each have a feature symbol? Requiring one is equivalent to requiring the other (and equivalent to requiring both, in either order), and `featurep' will always return the same value for each. The only reasons I can think of to have two such files separately are to 1. make them each smaller and easier to digest 2. hide some ugly hacks that aren't relevant to the package's interface 3. provide backwards compatibility with earlier versions of two packages that used to not be interdependent 4. connect two packages which somehow depend on each other and yet are maintained by different people. #1 and #2 can be resolved by having the one that is found by `require' `load' the other. #3 can be resolved by replacing one or both "old" packages with a "dummy" that merely requires the combined package and provides itself. #4 is likely to require more than merely turning the third `require' into a no-op: putting one of the `require's at the bottom, or doing something like (let ((combined-a-b-load t)) (require 'b)). Put differently, `provide' is supposed to "Announce that FEATURE is a feature of the current Emacs.". If you put it at the beginning of a package, you're lying (until the end of it). Davis -- This product is sold by volume, not by mass. If it appears too dense or too sparse, it is because mass-energy conversion has occurred during shipping.