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=-2.8 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_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 1494A1F461 for ; Sat, 11 May 2019 12:11:25 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 3C0F5120941; Sat, 11 May 2019 21:11:19 +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 2F43C1208B4 for ; Sat, 11 May 2019 21:11:16 +0900 (JST) Received: by filter0159p3mdw1.sendgrid.net with SMTP id filter0159p3mdw1-16535-5CD6BBE4-2D 2019-05-11 12:11:16.987422029 +0000 UTC m=+152997.991818095 Received: from herokuapp.com (unknown [3.93.58.81]) by ismtpd0042p1mdw1.sendgrid.net (SG) with ESMTP id q6LGXEHTQpiPk5KbxKtumg for ; Sat, 11 May 2019 12:11:16.946 +0000 (UTC) Date: Sat, 11 May 2019 12:11:17 +0000 (UTC) From: sawadatsuyoshi@gmail.com Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 68104 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 15829 X-Redmine-Issue-Author: foonlyboy 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=2F5TfLCefGvBaIElO7d3N8MbjO67cc?= =?us-ascii?Q?YMTnhPugOUeJ=2F2yb4u=2FfltZuUJZX=2FtTyUrihIIn?= =?us-ascii?Q?zkU+W4kMMeDKqxOoQLwn0psNLdyG50ALBLoowds?= =?us-ascii?Q?3EuiQQixtHDTg2qenYZUpRUBwsApHen0H1qU9gQ?= =?us-ascii?Q?vedJkmzjaNmKBSb5FTiwB=2Fou0Ww=2FjY5Fpkw=3D=3D?= To: ruby-core@ruby-lang.org X-ML-Name: ruby-core X-Mail-Count: 92621 Subject: [ruby-core:92621] [Ruby trunk Feature#15829] Object#then_if(condition){} 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 #15829 has been updated by sawa (Tsuyoshi Sawada). I have exactly the same concern as nobu. And that problem stems from the fact that, in this proposal, the condition is given as an argument of the method, which means that it has to be evaluated independently of the return value that appears in the middle of the method chain. That should take us back to #15547, where the condition is proposed to be given as a block (or proc, in a comment). ---------------------------------------- Feature #15829: Object#then_if(condition){} https://bugs.ruby-lang.org/issues/15829#change-77980 * Author: foonlyboy (Eike Dierks) * Status: Open * Priority: Normal * Assignee: * Target version: ---------------------------------------- I'd like to propose some sugar to Object#then There should be `Object#then_if(condition, &block)` The block should only be applied when the condition is true, otherwise the object should be returned without applying the block. Rationale: I frequently use `Object#then` with Rails to extend queries like this: ```ruby foo.then {|query| if(condition) query.where(zip:zap) else query end } ``` by using the proposed `Object#then_if` the example could be simplified to: ```ruby foo.then_if(condition) {|query| query.where(zip:zap) } ``` I believe that this also applies to a lot of other use cases, i.e. only applying some transformation if some condition is true, but otherwise leaving the result untouched. -- https://bugs.ruby-lang.org/