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Fri, 3 Jan 2025 18:44:06 +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=UCiliYePjbn9FTWrPYkjYPzL1QNpC+TRm+W81RMmSyI=; b=Skh2vqz3WMEwdNTdJGaekU8TzaH1XvvpuguTuLcw06wsLxzK5kwsujc3VMuCzWCZ9Jv4 eg92y3dQDZGqeP+05MfhOt2GM4Fr6vakStZYIW2Ifd1B5McpO1jFRS12zQ++fSVXmW8ndO ZZJVTdBlLqkQOW6icPAVYfromYGxMQXrHgfXcQBuOLUsxNp0P3A5OQ5eg3I2xN+S7jKvTs vF5n6KhprE+svyuApdU7cO8P5ymA9tzF++U26F/EnlwuvD/eF5yXVrnKHG9EmG6a4vYSq0 9p1ua6ktlFKrDkkDFb+E1xvgL4DTVyOnaW6zKLHPwIp7DcXLlMQbcF2T2C4gdJQQ== Received: by recvd-5f54b5d587-dffwj with SMTP id recvd-5f54b5d587-dffwj-1-67782FF5-E 2025-01-03 18:44:05.483264086 +0000 UTC m=+4310484.840371435 Received: from herokuapp.com (unknown) by geopod-ismtpd-7 (SG) with ESMTP id Find5JagTNelmh_fGmsp0w for ; Fri, 03 Jan 2025 18:44:05.406 +0000 (UTC) Date: Fri, 03 Jan 2025 18:44:05 +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: Dan0042 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: 97145 X-SG-EID: =?us-ascii?Q?u001=2EHy4LB1bizMxDg=2Fk6r7dYDS9qUDe3jZN8DIPm4OS+F86l7XdLFEAVX=2F2lh?= =?us-ascii?Q?z0Jj=2Ft7J6DgKnq5Qaf6Ba4+egck=2FoKuUHMa9Cn6?= =?us-ascii?Q?7D+EQ8vUJVvT+NALChivExunH6rxDlGFqKX3lRW?= =?us-ascii?Q?pXKSWflz5n9T=2F6+WAn1z1DZKC4On8f0lhfxF87y?= =?us-ascii?Q?+C6Nv=2FLVdq0vPnQdWgP=2Fh6OxZBNxJfrsuqh=2FZJ4?= =?us-ascii?Q?kMRE3a+fbt98oinobR7Sf=2F08FPBfVikec2f+0zw?= =?us-ascii?Q?BZzrxTA8jqJljROoK3n681N62g=3D=3D?= To: ruby-core@ml.ruby-lang.org X-Entity-ID: u001.I8uzylDtAfgbeCOeLBYDww== Message-ID-Hash: ZDJU2SHNZ7GR2GJSIUJLGSHUDX22B3IN X-Message-ID-Hash: ZDJU2SHNZ7GR2GJSIUJLGSHUDX22B3IN 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:120469] [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: "Dan0042 (Daniel DeLorme) via ruby-core" Cc: "Dan0042 (Daniel DeLorme)" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Issue #21000 has been reported by Dan0042 (Daniel DeLorme). ---------------------------------------- Feature #21000: A way to avoid loading constant required by a type check https://bugs.ruby-lang.org/issues/21000 * 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/