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 723F71F463 for ; Mon, 23 Dec 2019 08:57:11 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 3065D120A6E; Mon, 23 Dec 2019 17:56:59 +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 9D0EF120A48 for ; Mon, 23 Dec 2019 17:56:56 +0900 (JST) Received: by filterdrecv-p3las1-5bf99c48d-527wg with SMTP id filterdrecv-p3las1-5bf99c48d-527wg-18-5E00815C-E 2019-12-23 08:57:00.290373637 +0000 UTC m=+547871.025873324 Received: from herokuapp.com (unknown [18.233.7.172]) by ismtpd0053p1iad1.sendgrid.net (SG) with ESMTP id QPwLZJbQQZunEq57Pk2-mw for ; Mon, 23 Dec 2019 08:57:00.139 +0000 (UTC) Date: Mon, 23 Dec 2019 08:57:00 +0000 (UTC) From: sawadatsuyoshi@gmail.com Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 72080 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=2F5TfLCefGsQlwL1h=2F8yRYD5Dv9Zsk?= =?us-ascii?Q?vJuwMZiXb9CLWeiLea0WJG0+T3OavrIHcuFAS5+?= =?us-ascii?Q?5hOqBl2a311BiFFbGWdE6nnbHhOlMdqm1epwgbU?= =?us-ascii?Q?9HE3rbpft4i+X8lz4hklz3m3P86sA5H8vUSbBdD?= =?us-ascii?Q?Dq57uUxPFDbfv=2FGTAUJlRgo7kRXE1qGcw703cdH?= =?us-ascii?Q?w0QAzF9=2Fp+HK3G4XA=3D?= To: ruby-core@ruby-lang.org X-ML-Name: ruby-core X-Mail-Count: 96421 Subject: [ruby-core:96421] [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). knu (Akinori MUSHA) wrote: > Which does `hash1.transform_keys(hash2)` iterate over, hash1's keys or hash2's keys? My intention of including the key `:author` in `hash` was to show that the iteration is done over the receiver (your `hash1`), not the hash argument (your `hash2`). ---------------------------------------- Feature #16274: Transform hash keys by a hash https://bugs.ruby-lang.org/issues/16274#change-83344 * Author: sawa (Tsuyoshi Sawada) * Status: Open * Priority: Normal * Assignee: * Target version: 2.8 ---------------------------------------- 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 the old keys to the new keys follows 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/