[ruby-core:117243] [Ruby master Feature#8421] add Enumerable#find_map and Enumerable#find_all_map

["alexbarret (Alexandre Barret) via ruby-core" <ruby-core@ml.ruby-lang.org>]

Issue #8421 has been updated by alexbarret (Alexandre Barret).


zverok (Victor Shepelev) wrote in #note-4:
> @alexbarret There is a somewhat lesser-known trick which looks pretty close to your code:
> ```ruby
> # proposal:
> find_map(emails) do |email|
>   (matches = pattern.match(email)) && matches[:identifier]
> end
> # a "trick"
> emails.find { |email| match = pattern.match(email) and break match[:identifier] }
> # => "thecode"
> ```
> It might even be considered two tricks, depending on your point of view: the control-flow `and` allows to chain any statements to it (note it doesn't need extra parentheses after assignment), and `break value` allows to return a non-standard value from a block.
> 
> Not saying it is beautiful, just one more option.

Thanks I learned something, and it makes sense thinking about it. Both `and` and `break` aren't things I'm used to use in Ruby code but I'm glad I know this trick. Not sure I'll use it much. Breaking with another value than the expected value returned from the enumerable method can be confusing. 

----------------------------------------
Feature #8421: add Enumerable#find_map and Enumerable#find_all_map
https://bugs.ruby-lang.org/issues/8421#change-107330

* Author: Hanmac (Hans Mackowiak)
* Status: Feedback
----------------------------------------
currently if you have an Enumerable and you want to return the return value of #find you need eigther:
  (o = enum.find(block) && block.call(o)) || nil
or
  enum.inject(nil) {|ret,el| ret || block.call(el)}

neigher of them may be better than an directly maked method

same for #find_all_map
  enum.lazy.map(&:block).find_all{|el| el}

it may work but it is not so good



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