From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: Opaque objects and Emacs documentation Date: Tue, 21 Jul 2020 22:36:30 +0300 Message-ID: <83v9igfyo1.fsf@gnu.org> References: <20200712184908.13140.5739@vcs0.savannah.gnu.org> <20200712184909.BBC61209B1@vcs0.savannah.gnu.org> <7bf4d6ef-c0ec-43dc-ad5d-f6e81422ad90@yandex.ru> <83zh84m5ws.fsf@gnu.org> <3dd1c224-69b2-40af-5b2e-43a310253632@yandex.ru> <83tuybmtxs.fsf@gnu.org> <859f594b-1343-6d26-e1ac-7157c44eb56c@yandex.ru> <83a6zyk4tt.fsf@gnu.org> <6edffb7d-7708-534f-93ad-bf9180f5e0ed@yandex.ru> <835zamjsvk.fsf@gnu.org> <831rlajock.fsf@gnu.org> <1fcdc463-b3ab-2d32-31d7-904783ae0d81@yandex.ru> <83y2nii6sk.fsf@gnu.org> <750ecd90-0f89-5040-f737-2d8c1b8f01c9@yandex.ru> <83tuy3h87j.fsf@gnu.org> <412b0e60-7ccb-ee72-b361-566710156365@yandex.ru> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="34702"; mail-complaints-to="usenet@ciao.gmane.io" Cc: rms@gnu.org, emacs-devel@gnu.org To: Dmitry Gutov Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Tue Jul 21 21:37:10 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 1jxy4a-0008vm-JL for ged-emacs-devel@m.gmane-mx.org; Tue, 21 Jul 2020 21:37:08 +0200 Original-Received: from localhost ([::1]:57614 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jxy4Z-000132-Lw for ged-emacs-devel@m.gmane-mx.org; Tue, 21 Jul 2020 15:37:07 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:58566) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jxy47-0000de-Kw for emacs-devel@gnu.org; Tue, 21 Jul 2020 15:36:39 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:35183) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jxy47-0000NJ-Ce; Tue, 21 Jul 2020 15:36:39 -0400 Original-Received: from [176.228.60.248] (port=2151 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1jxy3z-0001rT-TJ; Tue, 21 Jul 2020 15:36:32 -0400 In-Reply-To: <412b0e60-7ccb-ee72-b361-566710156365@yandex.ru> (message from Dmitry Gutov on Tue, 21 Jul 2020 22:00:15 +0300) 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:253139 Archived-At: > Cc: npostavs@gmail.com, emacs-devel@gnu.org > From: Dmitry Gutov > Date: Tue, 21 Jul 2020 22:00:15 +0300 > > On 19.07.2020 17:48, Eli Zaretskii wrote: > > . a predicate to test whether an arbitrary Lisp value is an object > > of that type > > A predicate would look like: > > (defun project-instance-p (pr) > (condition-case nil > (progn > (project-roots pr) > t) > (error > nil))) I actually thought about cl-defgeneric etc., since obviously each type of project should have its own implementation. > But I don't see how it's going to help you write documentation. It makes the object system more complete. Suppose some application would like to check it gets a valid object, before dispatching? > > . a function to compare two objects of this type > > As discussed, it's a little function called 'equal'. Again, I envisioned a cl-defgeneric here. Using 'equal' only works for simple forms, but if we are willing to limit ourselves to such simple forms, why do we need generics at all?