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=-2.6 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, FORGED_GMAIL_RCVD,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS shortcircuit=no autolearn=no 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 31E0A1F4C0 for ; Wed, 23 Oct 2019 17:59:55 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 8DFEB120B05; Thu, 24 Oct 2019 02:59:46 +0900 (JST) Received: from o1678948x4.outbound-mail.sendgrid.net (o1678948x4.outbound-mail.sendgrid.net [167.89.48.4]) by neon.ruby-lang.org (Postfix) with ESMTPS id 83784120AE8 for ; Thu, 24 Oct 2019 02:59:44 +0900 (JST) Received: by filter0142p3mdw1.sendgrid.net with SMTP id filter0142p3mdw1-14147-5DB09514-D 2019-10-23 17:59:48.116156299 +0000 UTC m=+156239.416220266 Received: from herokuapp.com (unknown [52.91.158.104]) by ismtpd0049p1mdw1.sendgrid.net (SG) with ESMTP id hW51PtH-R1m6lzaR1CWr-Q for ; Wed, 23 Oct 2019 17:59:48.098 +0000 (UTC) Date: Wed, 23 Oct 2019 17:59:48 +0000 (UTC) From: bughitgithub@gmail.com Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 71101 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 14183 X-Redmine-Issue-Author: mame X-Redmine-Sender: bughit 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?Lz0+3qGVJFpKTmjP+6UJd2KKTsj+AtuP2yOGs8HtvQIWAInKOMlAWByRTN2grF?= =?us-ascii?Q?3tSV2e0LeUXYja5dVKDpIL+N96MPB9F22RV39MF?= =?us-ascii?Q?evwoiJ7Hzfe60oJK3BLb4QBnTa39bIhRExSjuo8?= =?us-ascii?Q?gdZ=2Fr6+PlWajnIlgUUeaav0cVPLtz8FTmhpeRHj?= =?us-ascii?Q?1pJrlODGPTWoNSlKXs=2FqdcWEJzKTpnWbG0g=3D=3D?= To: ruby-core@ruby-lang.org X-ML-Name: ruby-core X-Mail-Count: 95509 Subject: [ruby-core:95509] [Ruby master 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 bughit (bug hit). The original intent seems to have been to separate named args from hashes and make them a distinct language feature with more consistent, easier to understand syntax and semantics. However, how does the following fit with that goal: ```ruby def foo(a: nil, **args) args end foo(a: 1, 'a' => 2, 1 => 3, nil => 4, true => 5, Object.new => 6) ``` This invocation of foo should not be legal. `'a'`, `1`, `nil`, `true`, `Object.new`, are valid keys of a hash but they are not names of arguments, with which they are conflated. ---------------------------------------- Feature #14183: "Real" keyword argument https://bugs.ruby-lang.org/issues/14183#change-82285 * Author: mame (Yusuke Endoh) * Status: Closed * 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/