From: janosch84@... Date: 2019-07-27T09:38:24+00:00 Subject: [ruby-core:93948] [Ruby master Misc#15723] Reconsider numbered parameters Issue #15723 has been updated by janosch-x (Janosch M��ller). There might be one more reason for limiting the feature to a single argument referenced via `@` (or any other sigil/keyword): `@` can obscure the block signature. E.g. `record_finder.perform { @1.delete }` tells me nothing about the block signature. What if `#perform` used to pass one block argument but has been changed in the meantime to pass another important argument? I can't tell by looking at the code, and unlike the old syntax, this syntax will happily keep running, which I'm not sure is a good thing. If the newly added argument demoted the original argument to second place, this can lead to even worse surprises. ---------------------------------------- Misc #15723: Reconsider numbered parameters https://bugs.ruby-lang.org/issues/15723#change-80134 * Author: sos4nt (Stefan Sch����ler) * Status: Feedback * Priority: Normal * Assignee: matz (Yukihiro Matsumoto) ---------------------------------------- I just learned that *numbered parameters* have been merged into Ruby 2.7.0dev. For readers not familiar with this feature: it allows you to reference block arguments solely by their *index*, e.g. ```ruby [1, 2, 3].each { |i| puts i } # can become [1, 2, 3].each { puts @1 } ``` I have an issue with this new feature: I think **it encourages sloppy programming** and results in **hard to read code**. --- The [original proposal](https://bugs.ruby-lang.org/issues/4475) was to include a special variable (or keyword) with a **readable name**, something like: ```ruby [1, 2, 3].each { puts it } # or [1, 2, 3].each { puts this } ``` Granted, that looks quite lovely and it actually speaks to me ��� I can *understand* the code. And it fits Ruby: (quoting the website) > [Ruby] has an elegant syntax that is natural to read and easy to write. But the proposed `it` / `this` has limited application. It's only useful when dealing with a single argument. You can't have multiple `it`-s or `this`-es. That's why `@1`, `@2`, `@3` etc. were chosen instead. However, limiting the usefulness to a single argument isn't bad at at. In fact, a single argument seem to be the limit of what makes sense: ``` h = Hash.new { |hash, key| hash[key] = "Go Fish: #{key}" } # vs h = Hash.new { @1[@2] = "Go Fish: #{@2}" } ``` Who wants to read the latter? That looks like an archaic bash program (no offense). We already discourage Perl style `$`-references: (from [The Ruby Style Guide](https://github.com/rubocop-hq/ruby-style-guide#no-perl-regexp-last-matchers)) > Don't use the cryptic Perl-legacy variables denoting last regexp group matches (`$1`, `$2`, etc). Use `Regexp.last_match(n)` instead. I don't see how our code can benefit from adding `@1` and `@2`. Naming a parameter isn't useless ��� it gives context. With more than one parameter, naming is crucial. And yes, naming is hard. But avoiding proper naming by using indices is the wrong way. So please reconsider numbered parameters. Use a readable named variable (or keyword) to refer to the first argument or ditch the feature entirely. ---Files-------------------------------- implicit-param.diff (20 KB) -- https://bugs.ruby-lang.org/ Unsubscribe: