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=-3.9 required=3.0 tests=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 EB4001F4C0 for ; Wed, 23 Oct 2019 09:38:05 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id F1C16120A92; Wed, 23 Oct 2019 18:37:55 +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 509E2120A8E for ; Wed, 23 Oct 2019 18:37:53 +0900 (JST) Received: by filter0186p3mdw1.sendgrid.net with SMTP id filter0186p3mdw1-13118-5DB01F74-B 2019-10-23 09:37:56.143568906 +0000 UTC m=+125844.908905342 Received: from herokuapp.com (unknown [52.91.158.104]) by ismtpd0027p1mdw1.sendgrid.net (SG) with ESMTP id 1QhOJ_BxTfqSfgBOxzw-Tw for ; Wed, 23 Oct 2019 09:37:56.077 +0000 (UTC) Date: Wed, 23 Oct 2019 09:37:56 +0000 (UTC) From: duerst@it.aoyama.ac.jp Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 71091 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 16274 X-Redmine-Issue-Author: sawa X-Redmine-Sender: duerst 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?uQY=2F2xNrNfHHTWbKn6MBvvzfU5Pqk9I4lnOVb0CFDuua+B2XwmdEM8hZNSJ5Py?= =?us-ascii?Q?fXnB=2Fdz7iDptktN0EZeJvnVJW+bjCHEQN17fw0P?= =?us-ascii?Q?t0CzKN+HHwPled1uCFBFheN=2FBHwINaa3h+BND=2Fv?= =?us-ascii?Q?XMuspBWDCwVDMwFgNkoUD3MlAb7VoXsg=2FwJy5GG?= =?us-ascii?Q?jvovX+tgJwmx0GIpZynn=2FLRGGK+7bkPZRvg=3D=3D?= To: ruby-core@ruby-lang.org X-ML-Name: ruby-core X-Mail-Count: 95499 Subject: [ruby-core:95499] [Ruby master Feature#16274] Transform hash keys by a hash 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="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: ruby-core-bounces@ruby-lang.org Sender: "ruby-core" Issue #16274 has been updated by duerst (Martin D=FCrst). `String#gsub` also can take a block or a hash. Using a hash for `String#gsu= b` isn't possible in Perl or Python, but can be extremely handy. Maybe the = behavior when there's both a block and a hash could be the same as for `Str= ing#gsub`? ---------------------------------------- Feature #16274: Transform hash keys by a hash https://bugs.ruby-lang.org/issues/16274#change-82275 * Author: sawa (Tsuyoshi Sawada) * Status: Open * Priority: Normal * Assignee: = * Target version: = ---------------------------------------- We have `Hash#transform_keys` and its bang version to change the keys of a = hash, but that requires passing a block, which assumes that the mapping fro= m the old keys to the new keys follows some rule. But in reality, we freque= ntly want to change the keys where it is difficult to provide a rule. For e= xample, suppose we have: ``` hash =3D {created: 2019-10-23 17:54:46 +0900, updated: 2019-10-23 17:59:18 = +0900, author: "foo"} ``` and want to achieve: ``` {created_at: 2019-10-23 17:54:46 +0900, update_time: 2019-10-23 17:59:18 +0= 900, author: "foo"} ``` I request an option to change the keys of a hash not by giving a block, but= by passing a hash. I came up with two options. ### 1. Argument for `Hash#transform_keys` and its bang version Allow `Hash#transform_keys` to optionally take a hash argument instead of a= block. ``` hash.transform_keys({created: :created_at, updated: :update_time}) # =3D> {created_at: 2019-10-23 17:54:46 +0900, update_time: 2019-10-23 17:5= 9:18 +0900, author: "foo"} ``` ### 2. Argument for `Hash#slice` and the counterparts in other classes Since `Hash#slice` is often the first step of modifying a hash into some ot= her hash form, it makes sense to let it take an optional hash argument. ``` hash.slice(:created, :author, transform_keys: {created: :created_at}) # =3D> {created_at: 2019-10-23 17:54:46 +0900, author: "foo"} ``` With option 1, it could make sense to even allow a hash argument and a bloc= k simultaneously: ``` hash.transform_keys({created: :created_at, updated: :update_time}, &:to_s) # =3D> {"created_at" =3D> 2019-10-23 17:54:46 +0900, "update_time" =3D> 201= 9-10-23 17:59:18 +0900, "author" =3D> "foo"} ``` -- = https://bugs.ruby-lang.org/ Unsubscribe: