From: matthew@... Date: 2017-08-16T21:56:09+00:00 Subject: [ruby-core:82407] [Ruby trunk Feature#13820] Add a nill coalescing operator Issue #13820 has been updated by phluid61 (Matthew Kerwin). In perl I find `$x // $y` useful vs `$x || $y` because sometimes you want to accept `""` and `0` as values. In ruby the only 'defined' falsey value is `false`, so I'm not sure how useful this feature is here. If you're pulling options from a hash, for example, it's probably better to use a signal like `h.fetch k, d` to show that you accept falsey values from the hash, and/or `x.nil? ? y : x` to show that you explicitly only don't want `nil` ---------------------------------------- Feature #13820: Add a nill coalescing operator https://bugs.ruby-lang.org/issues/13820#change-66207 * Author: williamn (William Newbery) * Status: Open * Priority: Normal * Assignee: * Target version: ---------------------------------------- It would be nice if Ruby had an operator that only considered `nil` as false, like the null coalescing operators or "Logical Defined-Or operator" (Perl) found in some other languages. Ive seen things like `//` and `//=`m `??` and `??=`, or `?:` used for this. This would work like `||` and `||=` for short circuiting etc. except that only `nil` is considered a false condition. While Ruby considers only "false" and "nil" as false, with everything else true ("", [], {}, etc.) I still find occasionally people trip up when using logical or, `||` and `||=` when the value may be false. ```ruby a = 0 || 55 # = 0 Ruby already considers 0, "", etc. as true (oter languages do differ a lot here) a = 0 ?? 55 # = 0 So no change here a = nil || 55 # = 55, nil is false so right side is evaulated. a = nil ?? 55 # = 55, again no change a = false || 55 # = 55, however false is false for logical or a = false ?? 55 # = false, but its still a non-nil value ``` For example when doing things like: ```ruby def lazy @lazy ||= compute_this end def fetch(id, **opts) host = opts[:host] || default_host https = opts[:https] || true port = opts[:port] || (https ? 443 : 80) ... ``` Normally the intention is to use a default value or compute an action if no value is provided, which if the value may be false then requires special handling, or sometimes is missed and results in a bug. -- https://bugs.ruby-lang.org/ Unsubscribe: