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=AWL,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 593401F463 for ; Fri, 20 Dec 2019 07:31:35 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 4F89C120A5B; Fri, 20 Dec 2019 16:31:23 +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 CF555120A26 for ; Fri, 20 Dec 2019 16:31:21 +0900 (JST) Received: by filterdrecv-p3las1-5bf99c48d-s59nq with SMTP id filterdrecv-p3las1-5bf99c48d-s59nq-18-5DFC78CF-54 2019-12-20 07:31:27.895787383 +0000 UTC m=+283543.577196343 Received: from herokuapp.com (unknown [3.83.106.33]) by ismtpd0098p1iad2.sendgrid.net (SG) with ESMTP id sIpXHmLzTumr2-5yOV2n5g for ; Fri, 20 Dec 2019 07:31:27.794 +0000 (UTC) Date: Fri, 20 Dec 2019 07:31:27 +0000 (UTC) From: matz@ruby.or.jp Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 72030 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 16274 X-Redmine-Issue-Author: sawa 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=2Fmc2rfxRD2sZAksRKJIHVNKAvzbSt78CMQ6Y66Ab?= =?us-ascii?Q?7Q4Pma+tQBq8VvGI57hKgwys7srzoEoU3V1SUUy?= =?us-ascii?Q?yvdmXUHMcAMs1hdvTVp7J6EKbKMzOvL07S23xh8?= =?us-ascii?Q?=2FTyV9SykoL30D40K+aDzt9Q1cH2x9HSgN0UiCcK?= =?us-ascii?Q?=2F36tCoa5bVr1U5R=2FQCYqzGIpLX7OrzDNDFQ=3D=3D?= To: ruby-core@ruby-lang.org X-ML-Name: ruby-core X-Mail-Count: 96370 Subject: [ruby-core:96370] [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 matz (Yukihiro Matsumoto). I understand. Accepted. FYI, we do not accept a similar change to `transform_values`. Matz. ---------------------------------------- Feature #16274: Transform hash keys by a hash https://bugs.ruby-lang.org/issues/16274#change-83284 * 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 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/