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=-4.1 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED, 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 01C4320248 for ; Mon, 1 Apr 2019 14:52:45 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 1F34A121211; Mon, 1 Apr 2019 23:52:40 +0900 (JST) Received: from o1678916x28.outbound-mail.sendgrid.net (o1678916x28.outbound-mail.sendgrid.net [167.89.16.28]) by neon.ruby-lang.org (Postfix) with ESMTPS id 5509712120F for ; Mon, 1 Apr 2019 23:52:37 +0900 (JST) Received: by filter0061p3iad2.sendgrid.net with SMTP id filter0061p3iad2-7703-5CA225B3-20 2019-04-01 14:52:35.617034953 +0000 UTC m=+299134.553046962 Received: from herokuapp.com (unknown [54.84.241.30]) by ismtpd0050p1iad1.sendgrid.net (SG) with ESMTP id 6eE02brhTTWK0LUA47He1A for ; Mon, 01 Apr 2019 14:52:35.495 +0000 (UTC) Date: Mon, 01 Apr 2019 14:52:35 +0000 (UTC) From: matz@ruby.or.jp Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 67578 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 14183 X-Redmine-Issue-Author: mame X-Redmine-Sender: matz 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?bXEIHGfdFwsIlBTndiToCp=2Fmc2rfxRD2sZAksRKJIHVUL1H1=2Flvyr4gOC4SsEz?= =?us-ascii?Q?F3l7fltXM6gXtMn2KH7kO6ClT6UvRmcwDjQKs0L?= =?us-ascii?Q?D0LmKtP=2F0ee8IiB+baqu0VJ+S4NHKZSJeyYjVuh?= =?us-ascii?Q?s8=2FkRYLJcaE6zkREUQghG2veeijkNu+eb6Hv7da?= =?us-ascii?Q?o3RXh2RsqGr9n?= To: ruby-core@ruby-lang.org X-ML-Name: ruby-core X-Mail-Count: 92093 Subject: [ruby-core:92093] [Ruby trunk Feature#14183] "Real" keyword argument 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 #14183 has been updated by matz (Yukihiro Matsumoto). @jeremyevans0 I **will** investigate your proposal. I was not fully satisfied with the complete separation model proposed for 3.0, but I didn't think of any other model which is intuitive and clean, especially considering static type analysis. Your proposal could be a better alternative. Matz. ---------------------------------------- Feature #14183: "Real" keyword argument https://bugs.ruby-lang.org/issues/14183#change-77422 * Author: mame (Yusuke Endoh) * Status: Open * Priority: Normal * Assignee: * Target version: Next Major ---------------------------------------- In RubyWorld Conference 2017 and RubyConf 2017, Matz officially said that Ruby 3.0 will have "real" keyword arguments. AFAIK there is no ticket about it, so I'm creating this (based on my understanding). In Ruby 2, the keyword argument is a normal argument that is a Hash object (whose keys are all symbols) and is passed as the last argument. This design is chosen because of compatibility, but it is fairly complex, and has been a source of many corner cases where the behavior is not intuitive. (Some related tickets: #8040, #8316, #9898, #10856, #11236, #11967, #12104, #12717, #12821, #13336, #13647, #14130) In Ruby 3, a keyword argument will be completely separated from normal arguments. (Like a block parameter that is also completely separated from normal arguments.) This change will break compatibility; if you want to pass or accept keyword argument, you always need to use bare `sym: val` or double-splat `**` syntax: ``` # The following calls pass keyword arguments foo(..., key: val) foo(..., **hsh) foo(..., key: val, **hsh) # The following calls pass **normal** arguments foo(..., {key: val}) foo(..., hsh) foo(..., {key: val, **hsh}) # The following method definitions accept keyword argument def foo(..., key: val) end def foo(..., **hsh) end # The following method definitions accept **normal** argument def foo(..., hsh) end ``` In other words, the following programs WILL NOT work: ``` # This will cause an ArgumentError because the method foo does not accept keyword argument def foo(a, b, c, hsh) p hsh[:key] end foo(1, 2, 3, key: 42) # The following will work; you need to use keyword rest operator explicitly def foo(a, b, c, **hsh) p hsh[:key] end foo(1, 2, 3, key: 42) # This will cause an ArgumentError because the method call does not pass keyword argument def foo(a, b, c, key: 1) end h = {key: 42} foo(1, 2, 3, h) # The following will work; you need to use keyword rest operator explicitly def foo(a, b, c, key: 1) end h = {key: 42} foo(1, 2, 3, **h) ``` I think here is a transition path: * Ruby 2.6 (or 2.7?) will output a warning when a normal argument is interpreted as keyword argument, or vice versa. * Ruby 3.0 will use the new semantics. ---Files-------------------------------- vm_args.diff (4.19 KB) vm_args_v2.diff (4.18 KB) -- https://bugs.ruby-lang.org/