From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Original-To: poffice@blade.nagaokaut.ac.jp Delivered-To: poffice@blade.nagaokaut.ac.jp Received: from kankan.nagaokaut.ac.jp (kankan.nagaokaut.ac.jp [133.44.2.24]) by blade.nagaokaut.ac.jp (Postfix) with ESMTP id DC85319C0042 for ; Tue, 3 Nov 2015 05:08:06 +0900 (JST) Received: from voscc.nagaokaut.ac.jp (voscc.nagaokaut.ac.jp [133.44.1.100]) by kankan.nagaokaut.ac.jp (Postfix) with ESMTP id 88E2BB5D92A for ; Tue, 3 Nov 2015 05:36:44 +0900 (JST) Received: from neon.ruby-lang.org (neon.ruby-lang.org [221.186.184.75]) by voscc.nagaokaut.ac.jp (Postfix) with ESMTP id 6EF24952439 for ; Tue, 3 Nov 2015 05:36:44 +0900 (JST) Received: from [221.186.184.76] (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 3596C120485; Tue, 3 Nov 2015 05:36:42 +0900 (JST) X-Original-To: ruby-core@ruby-lang.org Delivered-To: ruby-core@ruby-lang.org Received: from o2.heroku.sendgrid.net (o2.heroku.sendgrid.net [67.228.50.55]) by neon.ruby-lang.org (Postfix) with ESMTPS id 76BF512046D for ; Tue, 3 Nov 2015 05:36:38 +0900 (JST) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sendgrid.me; h=from:to:references:subject:mime-version:content-type:content-transfer-encoding:list-id; s=smtpapi; bh=1yI5DH5Vb9VRLedn219wLe4hYGk=; b=hRqnV0q2DbilrrNkg+ CybnLZbLvxip6pZhaHHO9itK3Ror3x/Yh5VncaLAtprK1y2Y5LMzCrQ3tjyaxGoW 3twW9HzYZ4zlSpVLZ6bh35p6gqMAaJjdflE0I3jkGxTGpiuxJUYVU4ArwvbkKs95 DAVaDJw6pVCv7t+IQugusQ4oo= Received: by filter0468p1mdw1.sendgrid.net with SMTP id filter0468p1mdw1.14023.5637C95042 2015-11-02 20:36:32.945304769 +0000 UTC Received: from herokuapp.com (ec2-54-197-81-24.compute-1.amazonaws.com [54.197.81.24]) by ismtpd0006p1iad1.sendgrid.net (SG) with ESMTP id m1C8I4sWQVS9NQlUJp08uQ for ; Mon, 02 Nov 2015 20:36:32.801 +0000 (UTC) Date: Mon, 02 Nov 2015 20:36:32 +0000 From: gabe@binti.com To: ruby-core@ruby-lang.org Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Redmine-MailingListIntegration-Message-Ids: 45936 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 11643 X-Redmine-Issue-Author: gkop X-Redmine-Sender: gkop 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: ync6xU2WACa70kv/Ymy4QrNMhiuLXJG8OTL2vJD1yS4g6DBx1p3PTjlWyEg1XoYi05otnBCVjG+v+d JOisg5ags2Bh9SN8tqNcaBHBPrl10UoF0OiBKo7+WiOTvdqWUexEkToLrmRIHx8MV90jOIQ9I8oo2z pcRdqZibb/cYGghDTaGNG25jEvZAswqGrj8f X-ML-Name: ruby-core X-Mail-Count: 71300 Subject: [ruby-core:71300] [Ruby trunk - Feature #11643] A new method on Hash to grab values out of nested hashes, failing gracefully 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: , Errors-To: ruby-core-bounces@ruby-lang.org Sender: "ruby-core" Issue #11643 has been updated by Gabe Kopley. Matthew Kerwin wrote: > How about: > > params.?[:order].?[shipping_info].?[country] Thanks Matthew, I'll be honest, I hadn't thought of that. There is a certain appeal in avoiding adding a new method on Hash. On the other hand, by adding a new method we can more easily and more beautifully do metaprogramming, use a potentially more concise expression, convey more rich semantics, and possibly reduce the number of method calls. ---------------------------------------- Feature #11643: A new method on Hash to grab values out of nested hashes, failing gracefully https://bugs.ruby-lang.org/issues/11643#change-54672 * Author: Gabe Kopley * Status: Open * Priority: Normal * Assignee: ---------------------------------------- (I posted this to the mailing list last year [0] and received no response, but am inspired to file an issue here based on the positive reception to https://bugs.ruby-lang.org/issues/11537 ) This comes up sometimes in Rails programming [1]: `params[:order] && params[:order][:shipping_info] && params[:order][:shipping_info][:country]` or `params[:order][:shipping_info][:country] rescue nil` or `params.fetch(:order, {}).fetch(:shipping_info, {}).fetch(:country, nil)` What if Hash gave us a method to accomplish this more concisely and semantically? Eg. `params.traverse_nested_hashes_and_return_nil_if_a_key_isnt_found(:order, :shipping_info, :country)` Or to take a nice method name suggestion [2]: `params.dig(:order, :shipping_info, :country)` Another example solution is https://github.com/intridea/hashie#deepfetch (Although I don't like "fetch" in this method name since it doesn't and can't take a default value as an argument like Hash#fetch does) What do you all think? [0] https://groups.google.com/forum/#!topic/ruby-core-google/guleNgEJWcM [1] https://groups.google.com/d/msg/rubyonrails-core/bOkvcvS3t_A/QXLEXwt9ivAJ https://stackoverflow.com/questions/1820451/ruby-style-how-to-check-whether-a-nested-hash-element-exists https://stackoverflow.com/questions/19115838/how-do-i-use-the-fetch-method-for-nested-hash https://stackoverflow.com/questions/10130726/ruby-access-multidimensional-hash-and-avoid-access-nil-object [2] http://stackoverflow.com/a/1820492/283398 -- https://bugs.ruby-lang.org/