From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS4713 221.184.0.0/13 X-Spam-Status: No, score=-3.6 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from neon.ruby-lang.org (neon.ruby-lang.org [221.186.184.75]) by dcvr.yhbt.net (Postfix) with ESMTP id 81B581F463 for ; Fri, 13 Sep 2019 15:15:16 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 623FD1209CE; Sat, 14 Sep 2019 00:15:08 +0900 (JST) Received: from xtrwkhkc.outbound-mail.sendgrid.net (xtrwkhkc.outbound-mail.sendgrid.net [167.89.16.28]) by neon.ruby-lang.org (Postfix) with ESMTPS id 7506B1209C5 for ; Sat, 14 Sep 2019 00:15:05 +0900 (JST) Received: by filter0159p3mdw1.sendgrid.net with SMTP id filter0159p3mdw1-20755-5D7BB27B-80 2019-09-13 15:15:07.324556483 +0000 UTC m=+61959.707566273 Received: from herokuapp.com (unknown [54.242.69.183]) by ismtpd0032p1iad2.sendgrid.net (SG) with ESMTP id xVVlQNezTHCG1cXK-fYIeA for ; Fri, 13 Sep 2019 15:15:07.269 +0000 (UTC) Date: Fri, 13 Sep 2019 15:15:07 +0000 (UTC) From: merch-redmine@jeremyevans.net Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 70482 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 16157 X-Redmine-Issue-Author: Dan0042 X-Redmine-Sender: jeremyevans0 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-SG-EID: =?us-ascii?Q?RVE3t853K5scBhbmJHUzZTFFeVC=2FZSUmHZ0Dc+26wcEi2CTgsF1oz0wTSSxGGN?= =?us-ascii?Q?BI3EdTYd7fgLE+qxmKxk4ZkAI1jd=2F0EYQv+v81S?= =?us-ascii?Q?xuL=2FiDfr=2FqHFXYfX4309PAun9KeG7+4+Ppiwc6B?= =?us-ascii?Q?xR+qIZxt2gZ9XCBuU9LX+0XDBdvL7zRnSrR2745?= =?us-ascii?Q?gwEsAJwW7ePrGLTzK19oJPyKbxfZfSwTJrA=3D=3D?= To: ruby-core@ruby-lang.org X-ML-Name: ruby-core X-Mail-Count: 94928 Subject: [ruby-core:94928] [Ruby master Misc#16157] What is the correct and *portable* way to do generic delegation? X-BeenThere: ruby-core@ruby-lang.org X-Mailman-Version: 2.1.15 Precedence: list Reply-To: Ruby developers List-Id: Ruby developers List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ruby-core-bounces@ruby-lang.org Sender: "ruby-core" Issue #16157 has been updated by jeremyevans0 (Jeremy Evans). Dan0042 (Daniel DeLorme) wrote: > With 2.7, people will be asked to migrate their generic delegations to use `pass_keywords`. Then at some point in the future when 2.6 is no longer supported, `pass_keywords` will be deprecated and they'll be asked to migrate their generic delegations a second time, to use `(*args, **kw)` > > Is that the idea? `pass_keywords` is proposed only to make it easier to continue to support older versions of Ruby with the same method definition. I don't think we will be pushing people to use `pass_keywords`, merely making it available as an option. You are correct that `pass_keywords` is currently envisioned as a temporary solution, not a permanent one. However, there is nothing technically preventing it from being a permanent solution. For 2.7+, delegation using `(*args, **kw)` should work the same way `(*args)` works in Ruby <2.7. If you only want to migrate once and still want to support backwards compatibility, you can certainly switch to having separate definitions, using the current one for <2.7 and adding one for 2.7+. Then you could drop the <2.7 definition when you drop support for Ruby <2.7. ---------------------------------------- Misc #16157: What is the correct and *portable* way to do generic delegation? https://bugs.ruby-lang.org/issues/16157#change-81544 * Author: Dan0042 (Daniel DeLorme) * Status: Open * Priority: Normal * Assignee: ---------------------------------------- With the keyword argument changes in 2.7 we must now specify keyword arguments explicitly when doing generic delegation. But this change is not compatible with 2.6, where it adds an empty hash to the argument list of methods that do not need/accept keyword arguments. To illustrate the problem: ```ruby class ProxyWithoutKW < BasicObject def initialize(target) @target = target end def method_missing(*a, &b) @target.send(*a, &b) end end class ProxyWithKW < BasicObject def initialize(target) @target = target end def method_missing(*a, **o, &b) @target.send(*a, **o, &b) end end class Test def args(*a) a end def arg(a) a end def opts(**o) o end end # 2.6 2.7 3.0 ProxyWithoutKW.new(Test.new).args(42) # [42] [42] [42] ok ProxyWithoutKW.new(Test.new).arg(42) # 42 42 42 ok ProxyWithoutKW.new(Test.new).opts(k: 42) # {:k=>42} {:k=>42} +warn [{:k=>42}] incompatible with >= 2.7 ProxyWithKW.new(Test.new).args(42) # [42, {}] [42] [42] incompatible with <= 2.6 ProxyWithKW.new(Test.new).arg(42) # error 42 42 incompatible with <= 2.6 ProxyWithKW.new(Test.new).opts(k: 42) # {:k=>42} {:k=>42} +warn {:k=>42} must ignore warning? cannot use pass_positional_hash in 2.6 ``` I don't know how to solve this, so I'm asking for the **official** correct way to write portable delegation code. And by **portable** I mean code that can be used in gems that target ruby 2.6 and above. -- https://bugs.ruby-lang.org/