From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on starla X-Spam-Level: X-Spam-Status: No, score=0.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_BL_SPAMCOP_NET,SPF_HELO_PASS, SPF_PASS autolearn=no autolearn_force=no version=3.4.6 Received: from nue.mailmanlists.eu (nue.mailmanlists.eu [94.130.110.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id A92651F4CC for ; Mon, 6 Jan 2025 02:17:33 +0000 (UTC) Authentication-Results: dcvr.yhbt.net; dkim=pass (1024-bit key; unprotected) header.d=ml.ruby-lang.org header.i=@ml.ruby-lang.org header.a=rsa-sha256 header.s=mail header.b=nynkf65E; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ruby-lang.org header.i=@ruby-lang.org header.a=rsa-sha256 header.s=s1 header.b=Heibohd3; dkim-atps=neutral DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ml.ruby-lang.org; s=mail; t=1736129851; bh=aMqrN32uJbl9TmguVk3ArYdgXZpRMieCZGbyTYGP94E=; h=Date:References:To:Reply-To:Subject:List-Id:List-Archive: List-Help:List-Owner:List-Post:List-Subscribe:List-Unsubscribe: From:Cc:From; b=nynkf65EdH7sXpNHNKU4V19WN2fc1+X5Rx5d0Utn/bTObvgaxP1ZeXsKDHzOOoD44 WwKkt/rkD0zjgXHEWya9S8TRZQm6gzGkCAkYr+AjHe9KxIMy7IwLV8Um0Lxx5foO2G 8CKaLNMp12Mx2Fv04Y4re554c1WqYZlS5qHsaE8U= Received: from nue.mailmanlists.eu (localhost [IPv6:::1]) by nue.mailmanlists.eu (Postfix) with ESMTP id 5CF6F46527 for ; Mon, 6 Jan 2025 02:17:31 +0000 (UTC) Authentication-Results: nue.mailmanlists.eu; dkim=pass (2048-bit key; unprotected) header.d=ruby-lang.org header.i=@ruby-lang.org header.a=rsa-sha256 header.s=s1 header.b=Heibohd3; dkim-atps=neutral Received: from s.wrqvtbkv.outbound-mail.sendgrid.net (s.wrqvtbkv.outbound-mail.sendgrid.net [149.72.123.24]) by nue.mailmanlists.eu (Postfix) with ESMTPS id F2B2A44DC1 for ; Mon, 6 Jan 2025 02:17:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ruby-lang.org; h=from:references:subject:mime-version:content-type: content-transfer-encoding:list-id:to:cc:content-type:from:subject:to; s=s1; bh=PkQYMwHRKU42VHeC4nwXut7RS6PEqJiLR+MRLQQFyFs=; b=Heibohd3PnScAZ/h8hemwrWpURKJtAkjpV3xRAlUjolKa3sIYNni3d53teZyfmEnne7n KhWQX3cO6HaTuJvDH0pcnldw5o53a4Bam4+vVl/5IWA04BmVUgSJs1fvtYxYpjID6TmyFg pV3XtFfm+OaUdRzTDYszhLXK6vUyszDfTMo9MhETNUZNJoFmJKi0iT4EeAV0RFvrcgU7AX 1xcO0/Mr0OX8I1Igeu5+s+/sH6/CZgEoM/QO64OK+3wq0fKPE6RFdo0UD7a2Lz0OeTF+PW zwSasGSRRXaJF7Op/o83KBfBeqZQI6THswJSE0cNXZNUsLlTjnwsPh4smQUe4fCw== Received: by recvd-5f54b5d587-qstlq with SMTP id recvd-5f54b5d587-qstlq-1-677B3D34-1B 2025-01-06 02:17:24.9893828 +0000 UTC m=+4510555.529245233 Received: from herokuapp.com (unknown) by geopod-ismtpd-9 (SG) with ESMTP id 8JlbBzMHSr6ZgGzH2VL35Q for ; Mon, 06 Jan 2025 02:17:24.925 +0000 (UTC) Date: Mon, 06 Jan 2025 02:17:25 +0000 (UTC) Message-ID: References: Mime-Version: 1.0 X-Redmine-Project: ruby-master X-Redmine-Issue-Tracker: Feature X-Redmine-Issue-Id: 21000 X-Redmine-Issue-Author: Dan0042 X-Redmine-Issue-Priority: Normal X-Redmine-Sender: nobu X-Mailer: Redmine X-Redmine-Host: bugs.ruby-lang.org X-Redmine-Site: Ruby Issue Tracking System X-Auto-Response-Suppress: All Auto-Submitted: auto-generated X-Redmine-MailingListIntegration-Message-Ids: 97168 X-SG-EID: =?us-ascii?Q?u001=2E5PtzXJ23KrYzgM1nrOIr+EQ222PyrDaWSg0Er8CZ8tP86xyXmBM81zBKD?= =?us-ascii?Q?HreavdFYMbHjxXOR6UPMkt=2Fu9CyBIp6y52n8D2y?= =?us-ascii?Q?qA9zqurrgUeerJDf=2F0zxGTc7Ti=2F26MJdsQczEAf?= =?us-ascii?Q?vrRye3pL4ZypAerIm9C4woolR0k5TiBdwZY68Dg?= =?us-ascii?Q?4WuslQCzaPL68umFJnYzE64WmjPmPuSeXSKCzX+?= =?us-ascii?Q?arp2R4CwdyIF3y20YcnZDoFwMrr+AhvZILGpMLK?= =?us-ascii?Q?AppS0mZ95hocNuLFOZK1F3vpmw=3D=3D?= To: ruby-core@ml.ruby-lang.org X-Entity-ID: u001.I8uzylDtAfgbeCOeLBYDww== Message-ID-Hash: FBFRN3RPTW2NW4TRPULCL2NUAJ42S4WC X-Message-ID-Hash: FBFRN3RPTW2NW4TRPULCL2NUAJ42S4WC X-MailFrom: bounces+313651-b711-ruby-core=ml.ruby-lang.org@em5188.ruby-lang.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.9 Precedence: list Reply-To: Ruby developers Subject: [ruby-core:120492] [Ruby master Feature#21000] A way to avoid loading constant required by a type check List-Id: Ruby developers Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: From: "nobu (Nobuyoshi Nakada) via ruby-core" Cc: "nobu (Nobuyoshi Nakada)" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Issue #21000 has been updated by nobu (Nobuyoshi Nakada). Dan0042 (Daniel DeLorme) wrote: > ### defined?(mod) returns mod if it's a class/module > > If XYZ is a module, `defined?(XYZ)` could return XYZ instead of returning "constant". So it can be used in expressions like > > ```ruby > case obj > when nil > when defined?(XYZ) > > if obj and defined?(XYZ) === obj > > if defined?(Gem::Specification)&.respond_to?(:each) > ``` > Very versatile, with the downside that it's a small backward incompatibiliy. I like this, but we will need to consider the incompatibility and inconsistency with other constants. ---------------------------------------- Feature #21000: A way to avoid loading constant required by a type check https://bugs.ruby-lang.org/issues/21000#change-111277 * Author: Dan0042 (Daniel DeLorme) * Status: Open ---------------------------------------- There is this pattern I encounter sometimes: ```ruby if defined?(NameSpace::ClassName) and obj.is_a?(NameSpace::ClassName) ``` Searching in gems, the pattern is fairly common: https://pastebin.com/VGfjRWNu I would like a way to avoid the repetition of `NameSpace::ClassName` above. I can think of a number of ways to approach the issue, each with different tradeoffs... ### Pattern match ignores uninitialized constant Pattern match like `obj in XYZ` could return false if XYZ is not defined. The danger here is that a typo could go undetected and just silently ignore the error even when the constants is expected to be defined. ### Pattern match has special syntax to ignore uninitialized constant Pattern match such as `obj in XYZ?` (or some other syntax) could return false if XYZ is not defined. The downside is that we're adding yet more new syntax. But it could be `obj in defined?(XYZ)` and then it doesn't really feel like new syntax. ### Do not autoload constants required by pattern match If we have `autoload :XYZ, "xyz"` then `obj in XYZ` could skip the autoload and return false. There is a possibility that `XYZ` might be defined as a regexp or other matcher that return true, but in general autoload is only used for classes/modules. And if the class/module is not yet loaded, obviously an object of that type cannot exist so we can avoid loading it. But this would only work for autoloaded constants, so can't be used to check a library that might not be loaded, ex: `obj in ActiveRecord::Base` ### defined?(mod) returns mod if it's a class/module If XYZ is a module, `defined?(XYZ)` could return XYZ instead of returning "constant". So it can be used in expressions like ```ruby case obj when nil when defined?(XYZ) if obj and defined?(XYZ) === obj if defined?(Gem::Specification)&.respond_to?(:each) ``` Very versatile, with the downside that it's a small backward incompatibiliy. -- https://bugs.ruby-lang.org/ ______________________________________________ ruby-core mailing list -- ruby-core@ml.ruby-lang.org To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/