From: shevegen@... Date: 2017-08-16T12:44:43+00:00 Subject: [ruby-core:82401] [Ruby trunk Feature#13820] Add a nill coalescing operator Issue #13820 has been updated by shevegen (Robert A. Heiler). I am not sure that using a special-purpose operator would make a lot of sense. I myself use nil primarily as means to indicate a default, "non-set" value. The moment it is set to a boolean, be it false or true, is for me an indication that it has been "upgraded" (or set by a user on the commandline etc...) I do also tend to explicitely query for .nil? on some objects. By the way, did you actually propose an actual syntax? The two '?'? I do not think that ?? has any realistic chance for implementation due to ? already being used in ruby - in method definitions or ternary operator for example. People may wonder why there are so many ? coming out of nowhere. (For the record, I also consider || to be not pretty ... I strangely end up using a more verbose but explicit way to set or ensure defaults in ruby code. I would never write a line such as " port = opts[:port] || (https ? 443 : 80)" simply because it takes my brain too long to process what is going on there; my code always ends up being so simple that I do not have to think about it much at all). ---------------------------------------- Feature #13820: Add a nill coalescing operator https://bugs.ruby-lang.org/issues/13820#change-66203 * 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: <mailto:ruby-core-request@ruby-lang.org?subject=unsubscribe> <http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>