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 AA7011F4CC for ; Mon, 6 Jan 2025 14:29:28 +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=cPv+v7x6; 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=lp/3eEZx; dkim-atps=neutral DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ml.ruby-lang.org; s=mail; t=1736173736; bh=0UQUZznwUhtus7D6clTiXScSuuT1QkNXGwM/6RjVGiY=; 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=cPv+v7x66MoOq5X3P7rJXDgo7pd+CJpxopmsdFCm3YC4JCUlVyFDdI4o2qSiA6rMe Jajne62/35/TbQlgv21Ylu9GxIVqULJBTZpsk2/fEWltpwCJwsW51mZYEdDb43DH8y ehxuIVYKTVQ3wxV3qdZsTTuYlTdT7P5d3tLzOzSY= Received: from nue.mailmanlists.eu (localhost [IPv6:::1]) by nue.mailmanlists.eu (Postfix) with ESMTP id 12B2146769 for ; Mon, 6 Jan 2025 14:28:56 +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=lp/3eEZx; 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 C3A50466C2 for ; Mon, 6 Jan 2025 14:26:36 +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=mpovymB3njXLi0WxETk8MG/WT4Yhp57tKiqU7dVA5QU=; b=lp/3eEZxLn3PXsxTIvhoMGwIcSyzu+eccEL2TiN0Woe9GKXYQuNpBNKmwKbBB7R0KLLS C7OtFFhZp2jo04slMj9sEfzbAMOHdme19dsTVM4R/erNRcdiXtSliv0nZ6GTu/YKLQpMw7 Hkm4/CFOF//33zkSVssGS4Unh7CRZ6RjflzAAi7CnlUFCgGDAQKf9o+jrNwzTuecOhJtvk +nX5tOL0683BpzIf14ak9uNHIpV+XgnrEkEUYB8FxIjAdeP9UJn6JQRp87U8h0PKCRTkMS HZB1Prn9pVRTTnEYKHA5tHmgadQemA8nCLgokTphgCzJag+maUhZhMdKpJqVQj2Q== Received: by recvd-5f54b5d587-7rz2t with SMTP id recvd-5f54b5d587-7rz2t-1-677BE81B-8 2025-01-06 14:26:35.240587099 +0000 UTC m=+4554328.405439981 Received: from herokuapp.com (unknown) by geopod-ismtpd-33 (SG) with ESMTP id IxiTNsctSpC5tca7Po-PSw for ; Mon, 06 Jan 2025 14:26:35.191 +0000 (UTC) Date: Mon, 06 Jan 2025 14:26:35 +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: Eregon 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: 97178 X-SG-EID: =?us-ascii?Q?u001=2EByjZWvxTCjdoV8K03xEuhE7KqN4thWULFLM7+oH78KY30oYB3qFthsDpL?= =?us-ascii?Q?4w4cbYa3ttBh8bAHPOnE=2FkzPba67JNu7Lnrked2?= =?us-ascii?Q?O7K9VQ=2FJax2VG83ochkLWsgOukMKV8tgkRLBeGQ?= =?us-ascii?Q?ekuyLn2rhmf1eKsYNgd7128+XA0W8PFWZ0cYIsk?= =?us-ascii?Q?mxqdg+qXaYBIAmPYWJtu2jJFeUvmJBC8Fflh9aq?= =?us-ascii?Q?4xrY+RsSRh8ycEKz=2Fi=2FRMp+9ann0TbJNZuWAqeH?= =?us-ascii?Q?hFkSoT9OGrkUeoyX=2FvLWAyL6Fg=3D=3D?= To: ruby-core@ml.ruby-lang.org X-Entity-ID: u001.I8uzylDtAfgbeCOeLBYDww== Message-ID-Hash: FOZUIOZNHFEVJZK63A4PZCYIZWDSRXZ5 X-Message-ID-Hash: FOZUIOZNHFEVJZK63A4PZCYIZWDSRXZ5 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:120502] [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: "Eregon (Benoit Daloze) via ruby-core" Cc: "Eregon (Benoit Daloze)" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Issue #21000 has been updated by Eregon (Benoit Daloze). I'm unsure, I suppose it could be a compatibility concern. If you want to know if `Foo::Bar` exists and `Foo` is an autoload the only way to know is to load Foo and see if it has a constant `Bar`. So while surprising these semantics do make sense since `defined?` doesn't have a "it's an autoload (not yet loaded), I don't know" return value, it's either `nil` (doesn't exist) or `"constant"` (exists). ---------------------------------------- Feature #21000: A way to avoid loading constant required by a type check https://bugs.ruby-lang.org/issues/21000#change-111295 * 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/