From: daniel@...42.com Date: 2019-08-26T19:34:03+00:00 Subject: [ruby-core:94588] [Ruby master Feature#16120] Implicit block argument if block starts with dot-method call Issue #16120 has been updated by Dan0042 (Daniel DeLorme). The syntax I propose is definitely not *meant* to absorb all styles. I think any attempt to be everything to everyone is doomed to failure. I do not believe this is a race where only one of the various proposals can win; considering the various proposals together means finding the right balance, not finding a single all-purpose solution. In fact I find that `map{ .to_s(16) }` and `map(&JSON.:parse)` are very complementary... * `map{ .to_s(16) }` is shorthand for `map{ |x| x.to_s(16) }`; each element is the receiver of a message; this is OO style. I would use that a lot. * `map(&JSON.:parse)` is shorthand for `map{ |x| JSON.parse(x) }`; each element is the argument of a function; this is functional style, for people who want first-class functions in ruby. I would likely never use that. But I don't mind others who want to use that style. ---------------------------------------- Feature #16120: Implicit block argument if block starts with dot-method call https://bugs.ruby-lang.org/issues/16120#change-81055 * Author: Dan0042 (Daniel DeLorme) * Status: Open * Priority: Normal * Assignee: * Target version: ---------------------------------------- How about considering this syntax for implicit block parameter: ``` [10, 20, 30].map{ .to_s(16) } #=> ["a", "14", "1e"] ``` Infinite thanks to @maedi for [the idea](https://bugs.ruby-lang.org/issues/15723#note-19) This proposal is related to #4475, #10829, #12115, #15302, #15483, #15723, #15897, #16113 (and probably many others) which I feel are all trying to solve the same "problem". So I strongly believe all these feature requests should to be considered together in order to make a decision. This "problem" can be more-or-less stated thus: * There is a very common pattern in ruby: `posts.map{ |post| post.author.name }` * In that line, the three 3 "post" in close proximity feel redundant and not DRY. * To reduce the verbosity, people tend to use a meaningless one-character variable in the block * But even so `posts.map{ |p| p.author.name }` still feels redundant. * This "problem" is felt by many in the ruby community, and is the reason people often prefer `posts.map(&:author)` * But that only works for one method with no arguments. * This results in many requests for a block shorthand than can do more. I realize that many people feel this is not a problem at all and keep saying "just use regular block syntax". But the repeated requests over the years, as well as the widespread usage of `(&:to_s)`, definitely indicate this is a wish/need for a lot of people. Rather than adding to #15723 or #15897, I chose to make this a separate proposal because, unlike `it` or `@` implicit variables, it allows to simplify **only** `{ |x| x.foo }`, not `{ |x| foo(x) }`. This is on purpose and, in my opinion, a desirable limitation. The advantages are (all in my opinion, of course) * Extremely readable: `posts.map{ .author.name }` * Possibly even more than with an explicit variable. * Of all proposals this handles the most important use-case with the most elegant syntax. * It's better to have a beautiful shorthand for 90% of cases than a non-beautiful shorthand for 100% of cases. * A shorthand notation is less needed for `{ |x| foo(x) }` since the two `x` variables are further apart and don't feel so redundant. * No ascii soup * No potential incompatibility like `_` or `it` or `item` * Very simple to implement; there's just an implicit `|var| var` at the beginning of the block. * In a way it's similar to chaining methods on multiple lines: posts.map{ |post| post .author.name } It may be interesting to consider that the various proposals are not *necessarily* mutually exclusive. You *could* have `[1,2,3].map{ .itself + @ + @1 }`. Theoretically. I feel like I've wanted something like this for most of the 16 years I've been coding ruby. Like... **this** is what I wanted that `(&:to_s)` could only deliver half-way. I predict that if this syntax is accepted, most people using `(&:to_s)` will switch to this. -- https://bugs.ruby-lang.org/ Unsubscribe: