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: [PATCH] elisp manual patch: add to file notification documentation Date: Tue, 13 Dec 2022 13:06:28 -0500 Message-ID: References: <87bko8knq2.fsf@rabkins.net> <87k02vu32l.fsf@gmx.de> <871qp3i4wu.fsf@rabkins.net> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="14785"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: Michael Albinus , Stefan Kangas , emacs-devel To: Yoni Rabkin Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Tue Dec 13 19:06:59 2022 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 1p59gB-0003d9-Bw for ged-emacs-devel@m.gmane-mx.org; Tue, 13 Dec 2022 19:06:59 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1p59fo-0000PN-NR; Tue, 13 Dec 2022 13:06:36 -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 1p59fn-0000OR-Gq for emacs-devel@gnu.org; Tue, 13 Dec 2022 13:06:35 -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 1p59fl-0003Ko-FZ for emacs-devel@gnu.org; Tue, 13 Dec 2022 13:06:35 -0500 Original-Received: from pmg2.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id BCC7B80853; Tue, 13 Dec 2022 13:06:31 -0500 (EST) Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 1735E80014; Tue, 13 Dec 2022 13:06:30 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1670954790; bh=iWxs4Gn8sezVCmxNgGyp1phhWPjevjeEu3LhZqNvOzQ=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=BZrbpzG5D86qRdJGtBrHrp/cfiuVBLXlFcHPD+zQYhI8zaA+GmZr0uc2ZOp1YQksI Yz+VPM0gwqa/zt3821EFlVeTmAaZOhsBeAfHO2Z+e+7iwCm4gyWvfsmIf0qT0jWAdm mkgPwbxJLb/doW+mk55h3fWBpvqomEwuk2f/Is6pxKvqcK/ZG45nJpyihObrPZh6VU Pz4aex8J96+/cwZsbCZ9bKNlNepUdgW0UrpFkaf5Jn3oSMOVhh2OrQKUXU1Gtz7DK4 naDv97wT+TPoP2Pe8Uo3H3b2YdDHG8QK+5eV9GRaoAzqFBaPPv0KRzzcnC5sx8uK0u ML8brmduUrERg== Original-Received: from pastel (unknown [45.72.193.52]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id DD55B12016C; Tue, 13 Dec 2022 13:06:29 -0500 (EST) In-Reply-To: <871qp3i4wu.fsf@rabkins.net> (Yoni Rabkin's message of "Tue, 13 Dec 2022 12:34:25 -0500") 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 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:301337 Archived-At: > The documentation for `file-notify-add-watch' says: "If the file cannot > be watched for some reason, this function signals a `file-notify-error' > error." If this error is not good enough, maybe we should improve it, e.g. it could return different contents depending on whether the problem is a lack of notification support in Emacs, or a lack of notification support for this particular file/dir (e.g. via Tramp), etc... > I think that there is value in documenting a way for us to check if the > emacs we are running supports file notification, short of actually > trying to run `file-notify-add-watch', getting a generic > `file-notify-error', and reading the associated message to find out if > it is a simple problem, like a missing directory, or a difficult > problem, like a missing library. I guess it depends what you intend to do with that info. AFAIK all callers of `file-notify-add-watch` need to handle the case where the addition fails, but I wonder how you intend to use the specific kind of error in the rest of the code. I guess you could also perform a dummy `file-notify-add-watch` on something like $HOME as a way to check whether there is basic support for file notifications. Stefan