From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Attaching context info to an error Date: Thu, 28 Dec 2023 14:22:20 -0500 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="5448"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: emacs-devel@gnu.org To: =?windows-1252?B?Sm/jbyBU4XZvcmE=?= Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Thu Dec 28 20:23:15 2023 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 1rIvyL-0001DB-UZ for ged-emacs-devel@m.gmane-mx.org; Thu, 28 Dec 2023 20:23:14 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rIvxi-0007DO-2J; Thu, 28 Dec 2023 14:22:34 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rIvxf-0007DG-VS for emacs-devel@gnu.org; Thu, 28 Dec 2023 14:22:31 -0500 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rIvxe-0002xZ-06 for emacs-devel@gnu.org; Thu, 28 Dec 2023 14:22:31 -0500 Original-Received: from pmg3.iro.umontreal.ca (localhost [127.0.0.1]) by pmg3.iro.umontreal.ca (Proxmox) with ESMTP id AFB184423EA; Thu, 28 Dec 2023 14:22:27 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1703791346; bh=d2R/yepODHawTdNBE8TmElnUTtFFUKes4vHcBa3lGyo=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=n8sXEzNnsbUTO966cVeG/Tbg6F7+YUZH9W9pfQFnZ15HuBgShhUULszTM/+7xC/NF XXHkmyMR/XlLBlMC3Xj0H0i5EfY1XKcoi6nRzRTmJbf9sUILKEnJ9LTyXHOUS//l0G 1vFy6YT/sRTkq6iWwaT30tHNbMmWUkno0fDBoh0K5I5tkeYlwDObgxzb+8moLLVPgN KXlA2bxXFGk8FpAYl7VCEVnPguYP7tYT/f3XYTILdm28DB6DrCtADblcxkPLlyKx9a W+NBr1dPpQ1vx8qk2OoTl5JgHhmPqA7poUyO2CRfbkHmO4RyW3RpXJQnk87AgkpK13 cuE0asoZ6ULrg== Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg3.iro.umontreal.ca (Proxmox) with ESMTP id 1C1754423E8; Thu, 28 Dec 2023 14:22:26 -0500 (EST) Original-Received: from pastel (65-110-221-238.cpe.pppoe.ca [65.110.221.238]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id EA9CC1210C3; Thu, 28 Dec 2023 14:22:25 -0500 (EST) In-Reply-To: (=?windows-1252?Q?=22Jo=E3o_T=E1vora=22's?= message of "Thu, 28 Dec 2023 17:15:11 +0000") Received-SPF: pass client-ip=132.204.25.50; envelope-from=monnier@iro.umontreal.ca; helo=mailscanner.iro.umontreal.ca X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:314291 Archived-At: > Just see eglot.el and jsonrpc.el for examples. It's a constructor > in the C++ style. Meaning the client of the library, when making > an object, won't get just a bunch of data. They will either > get a fully functioning object _or_ an error. You can't do that > in plain Elisp without "-init" custom constructors, just as > you can't do that in C without foo = (Foo*)malloc() + init_foo(foo). Not sure where using a "smart constructor" function (what you call "-init" custom constructor) is less work than defining a `initialize-instance` method. > Furthermore, just like in typical OO, derivation of such classes > are guaranteed to have the base class parts valid and constructed > in their `intialize :after` this is the bread and butter of CLOS, > and it's awkward and error-prone to program without it. Ah... I think I'm beginning to see why I don't see the benefit: in my world, objects are basically immutable, so an object that's partly initialized (as in your "have the base class parts valid") is just already very weird :-) > Right, it's because I _know_ that you wrote these things that I find > it odd you do now see how useful they are. There's a difference between knowing how to build a car and being a good driver, yes. I can write a Prolog interpreter but my Prolog programming skills suck. Similarly, I'm more comfortable using Haskell-style type classes (or the closely related C++ templates) than "classic OOP" with subtyping. >> Redefinition of a class is definitely not currently supported (with no >> plan to support it in the foreseeable future). > In this case, it was a new version of jsonrpc.el that has to > be backward compatible to clients programming against the older > version. Then your bug report would be a feature request, I guess. E.g. include a small patch to `jsonrpc.el` showing the code you would *like* to use. > CLOS class redefinition is big business indeed, but just removing > a slot here in the same image worked nicely here for demonstration > purposes: it still errored as reassuringly as it would have if in > another Emacs session. Yes, I'm aware of this. But ELisp is a fairly limited "programming system" (as opposed to programming language", see doi:10.1145/2384592.2384611). I'm a PL guy and one from the functional programming side (i.e. averse to mutation) to boot, so redefining the classes of existing objects makes my head hurt. Stefan