From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Dmitry Gutov Newsgroups: gmane.emacs.devel Subject: Re: master 1e3b0f2: Improve doc strings of project.el Date: Sat, 18 Jul 2020 14:58:59 +0300 Message-ID: <704e75d3-ca35-6a1b-0780-f8a3ecda9d79@yandex.ru> References: <5d59dd9b-0848-691a-615e-c16d2070b92d@yandex.ru> <837dv8oida.fsf@gnu.org> <834kqcoghk.fsf@gnu.org> <99bb8976-580a-ef8e-6b7d-130c3ca5cb8a@yandex.ru> <83y2nom3hy.fsf@gnu.org> <20200713075842.GA4332@tuxteam.de> <21b47cbb-d1aa-d875-2944-deebb7583961@yandex.ru> <20200717152702.GA18658@tuxteam.de> <922bca06-3425-6fa3-b184-89942c75e91d@yandex.ru> <20200718090546.GC30436@tuxteam.de> <835zali167.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="32102"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 Cc: emacs-devel@gnu.org To: Eli Zaretskii , tomas@tuxteam.de Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sat Jul 18 13:59:49 2020 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jwlVN-0008Fd-4v for ged-emacs-devel@m.gmane-mx.org; Sat, 18 Jul 2020 13:59:49 +0200 Original-Received: from localhost ([::1]:43290 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jwlVM-00029K-7z for ged-emacs-devel@m.gmane-mx.org; Sat, 18 Jul 2020 07:59:48 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:47728) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jwlUf-0001Yy-UM for emacs-devel@gnu.org; Sat, 18 Jul 2020 07:59:06 -0400 Original-Received: from mail-ed1-x543.google.com ([2a00:1450:4864:20::543]:43024) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jwlUe-0006pU-Ad; Sat, 18 Jul 2020 07:59:05 -0400 Original-Received: by mail-ed1-x543.google.com with SMTP id a1so9630743edt.10; Sat, 18 Jul 2020 04:59:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=jE+1CNoQZ7Y+HRT/8FIif8sc2h1vlgyl52YsfoUzX1Y=; b=uIhZZMyKJ7d9Io9/yrfpkbIe3lvcCCC2OX8c72jKzGmVUZsgokDMBCYZro4ekH+8Il ULn84vNqgZkzSpVW3bYAEtTvqwkWyTijDlr2klzs09uhcVLSlxOcUxj1p9iDk/6BFxII nQ98TLI3v6VVgIdzhJs3perXWvPOGBpIll5VYGZO9JBYE+BjerU0eyVDu5Xf75ef3QhW xpbzpV/rWjvdW7mSjCJd0MHE+Jm+S4QuAnD0JCw23K78/7zBx0RcIGw7enDvxZGo92pP EyP3NWY1UWWz+vfZ0NWQa71qh8Z6v1NbR0dVPyTbDuuR44mAkAQ1VcZLbBB3d99DbSLr 1qDQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:subject:to:cc:references:from:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=jE+1CNoQZ7Y+HRT/8FIif8sc2h1vlgyl52YsfoUzX1Y=; b=Ln+aX4v2m9vdZUN0bQb8V7CEDJi3QYlIHhpcf6tiy5jYJZfN0Af56q458GoWQp1Frc Y0HgIdMI6fCOaIj4T5ZTyzBJJWBehTRoB3LdsdRHELvxVS3jeAP/MRCe17MiSAL4U0nj UQiyITHWhi47y4vqxiwUzJfz9/F2BF6g67+r9mUBmpXxdRUU7N8EQgaeYSwV8l3RA+ir itB298ZBYO5XRTkdACu55Zv3HUudBhdNhQ4jBHcGKn0zlfbAQI5lX3NewX246YLIRrXo cE5NeiE84btr3Zk9O2/3r82U33/Gvh7fMEFbqXxx7RNMwWpUvZQVHXCphD4clbRNPm4/ qb3Q== X-Gm-Message-State: AOAM533mtIv3LUk1xuBZU6jxURyDhxHDwX0Nxya71Zciu1QBXEIVzb4N hfWmolcydnVYtj6OsHXAfAB4k3+G X-Google-Smtp-Source: ABdhPJwCpIWrPqMunpFyfciU4NJV2YTons4oSMkCSqoNO7R1ypmaL0TCjpvd2JFWFdUJXPOqAXJC0A== X-Received: by 2002:a50:8e53:: with SMTP id 19mr13766582edx.185.1595073541572; Sat, 18 Jul 2020 04:59:01 -0700 (PDT) Original-Received: from [192.168.0.3] ([66.205.73.129]) by smtp.googlemail.com with ESMTPSA id l22sm10431469ejr.98.2020.07.18.04.58.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 18 Jul 2020 04:59:00 -0700 (PDT) In-Reply-To: <835zali167.fsf@gnu.org> Content-Language: en-US Received-SPF: pass client-ip=2a00:1450:4864:20::543; envelope-from=raaahh@gmail.com; helo=mail-ed1-x543.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: 0 X-Spam_score: 0.0 X-Spam_bar: / X-Spam_report: (0.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FORGED_FROMDOMAIN=1, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 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-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:253070 Archived-At: On 18.07.2020 13:10, Eli Zaretskii wrote: >> Date: Sat, 18 Jul 2020 11:05:46 +0200 >> From: tomas@tuxteam.de >> Cc: emacs-devel@gnu.org >> >>> I could be wrong in some details here, but a file descriptor seems >>> like a prime example of an abstraction. >> >> Well, that's at the Mother of Abstraction, aka the user space/kernel >> space barrier :-) > > IMO, there's nothing opaque about a file descriptor. It is just a > number. The abstraction here isn't in the descriptor itself, it's in > what it _represents_. Potato, pot-ah-to. > The descriptor is actually a _handle_ for an > object that itself is not exposed at all; you can only manipulate it > via the handle. So it's actually even more opaque. >> Yes, this is some kind of OO. But it leaks a couple of things: >> first, it's a "small number" (i.e. not some random 64 bit >> address, but the pattern of counting up from zero and of building >> bitmaps of FDs is considered --mostly-- viable), i.e. the mental >> model around is that the kernel "has" a table somewhere indexed >> by FD. This detail wasn't probably intended to leak in the first >> place, but was just "the obvious thing to do" in a world in which >> machines with a 32 bit address space were considered serious iron. > > That detail is not a general trait of a handle. Another popular > example of a handle is a FILE pointer in C, where the details of the > object it points to are generally not public. Here, the numerical > value of the handle is no longer small. A FILE pointer is less interesting, given that the structure on the other end is usually more or less the same. Even if it's concealed. > Yet another similar abstraction, much more close to our domain, is the > Lisp_Object representation on the C level: with a couple of > exceptions, each object is actually a handle of a C struct; Exactly. "There's nothing opaque about a project instance. It is just a Lisp_Object." > P.S. The interpretation of a file descriptor as an index into some > small table doesn't hold in modern OSes anyway. It was true for > MS-DOS, but modern OSes have moved away of that. Meaning that it's an abstraction that stood the test of time.