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Feature #16120

Updated by Dan0042 (Daniel DeLorme) about 1 year ago

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. 

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