From: daniel@...42.com Date: 2019-08-27T14:43:23+00:00 Subject: [ruby-core:94610] [Ruby master Feature#16120] Omitted block argument if block starts with dot-method call Issue #16120 has been updated by Dan0042 (Daniel DeLorme). Description updated Subject changed from Implicit block argument if block starts with dot-method call to Omitted block argument if block starts with dot-method call @nobu, wow, thank you so much. I never imagined it would be THAT simple to implement. `O_O @_@ m(_ _)m` But I do think it would be better with `(parser_numbered_param(p, 0))` in the commit [here](https://github.com/ruby/ruby/commit/7d14171d959f4088b04ca892cb36472171fa01e9) `m(_ _)m` --- jeremyevans0 (Jeremy Evans) wrote: > In the cases it does handle, it does save a character compared to the implicit parameter approach. I don't think that character saving makes the code clearer than the single implicit parameter approach, though. In my opinion they are even in terms of clarity. I totally agree that "saving" a single character makes no difference. But all these proposals are not about reducing mere character count, they're about reducing... I don't know the right word... cognitive complexity? lexical redundancy? conceptual overhead? It's the reason why people propose `{item.foo}` even though it has *zero* characters less than `{|x|x.foo}`. It's the reason why people who use nice descritive variable and method names can also propose `{@.foo}` even though it's an insignificant three character saving. It's the reason why human languages use omissions and pronouns. Allow me to make a comparison with english: ``` omitted {.foo} John went to the market and bought apples implicit {@.foo} John went to the market and he bought apples explicit {|x|x.foo} John went to the market and John bought apples ``` There's a reason why the first form is the most natural. When people talk about a block shorthand, I really think they mean shorter in the sense of cognition, not character count (although the two are somewhat related). So rather than thinking of a 1-char saving, it's more like explicit has 2x overhead, implicit has 1x, and omitted has 0x. Yes, we're talking about a very very tiny amount of overhead, I'll grant you, but enough to have these proposals keep popping up. That's not to say the implicit parameter approach is bad, in fact I rather like it. I just happen to think the omitted approach has so much better "flow". 1x/0x = Infinity kind of thing. > I think the implicit parameter approach (`{JSON.parse(@)}`) is a simpler and more readable approach than the dot-colon approach (`(&JSON.:parse)`). I totally agree there again. I was trying to present the perspective of functional-style first-class-function people (which I am not). Maybe trying to argue on behalf of others is a mistake in itself. ---------------------------------------- Feature #16120: Omitted block argument if block starts with dot-method call https://bugs.ruby-lang.org/issues/16120#change-81086 * 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, #9076, #10829, #12115, #15302, #15483, #15723, #15799, #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: