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 83E421F4C0 for ; Wed, 23 Oct 2019 09:20:26 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 04155120A90; Wed, 23 Oct 2019 18:20:17 +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 645CB120A8F for ; Wed, 23 Oct 2019 18:20:15 +0900 (JST) Received: by filter0155p3mdw1.sendgrid.net with SMTP id filter0155p3mdw1-24463-5DB01B55-1B 2019-10-23 09:20:21.190893226 +0000 UTC m=+125072.524647224 Received: from herokuapp.com (unknown [52.91.158.104]) by ismtpd0060p1iad1.sendgrid.net (SG) with ESMTP id _dc951hoSFSb7pzqQzYmVQ for ; Wed, 23 Oct 2019 09:20:21.168 +0000 (UTC) Date: Wed, 23 Oct 2019 09:20:21 +0000 (UTC) From: sawadatsuyoshi@gmail.com Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 71090 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 16274 X-Redmine-Issue-Author: sawa X-Redmine-Sender: sawa 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?jFXA8Rt481sXUUIO9tYW1AJlMOZdNdlSw=2F5TfLCefGugB5bNrZ1J8Hz5vgmdyH?= =?us-ascii?Q?mtN+q+gIToBDG2bn=2F3kO0IUqGb1G+NqjfJN9h8H?= =?us-ascii?Q?A+GtOWalByGwisyysSj1TX+FDYQLi8k0cIGZjBT?= =?us-ascii?Q?yszTWvl2KuQVMKoHjzgDkfeKftSFfIgvTrpKHgb?= =?us-ascii?Q?lJcP42pVZLn8gjBhIQdMAaGS7WwmXFlUaMw=3D=3D?= To: ruby-core@ruby-lang.org X-ML-Name: ruby-core X-Mail-Count: 95498 Subject: [ruby-core:95498] [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="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ruby-core-bounces@ruby-lang.org Sender: "ruby-core" Issue #16274 has been updated by sawa (Tsuyoshi Sawada). shyouhei (Shyouhei Urabe) wrote: > Understand the motivation (maybe that of #slice can be separated into another request). > > One quick question: what should happen if _both_ a block and an argument are passed at once? Actually, I just came up with an additional idea regarding that exact point. Updated the issue. ---------------------------------------- Feature #16274: Transform hash keys by a hash https://bugs.ruby-lang.org/issues/16274#change-82273 * 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 from old keys to new keys follow some rule. But in reality, we frequently want to change the keys where it is difficult to provide a rule. For example, suppose we have: ``` hash = {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 +0900, 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}) # => {created_at: 2019-10-23 17:54:46 +0900, update_time: 2019-10-23 17:59:18 +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 other hash form, it makes sense to let it take an optional hash argument. ``` hash.slice(:created, :author, transform_keys: {created: :created_at}) # => {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 block simultaneously: ``` hash.transform_keys({created: :created_at, updated: :update_time}, &:to_s) # => {"created_at" => 2019-10-23 17:54:46 +0900, "update_time" => 2019-10-23 17:59:18 +0900, "author" => "foo"} ``` -- https://bugs.ruby-lang.org/