[ruby-core:117242] [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).


jeremyevans0 (Jeremy Evans) wrote in #note-5:
> `find_map` seems like a bad name as there is no map. map implies calling the same function over all elements in a collection, and in this case, there would be a single element (or none if nothing was found).  Combining `find` and `then` seems like the simplest way now if you don't want to use `break`:

This is a good point. I always thought map was the action of transforming an element but it does have a implicit reference to an array or a collection.

> 
> ```ruby
> emails.find{ pattern.match(it) }&.then{ it[:identifier] }
> ```
> 
> Personally, I would use the following approach is I think it is clearer:
> 
> ```ruby
> if match = emails.find{ pattern.match(it) }
>   match[:identifier]
> end
> ```

The code aboce doesn't work ^. `match` variable assigned is an email string not the matches found from the email. We implicitly thought that `find` was returning the matches not the item iterated over.

----------------------------------------
Feature #8421: add Enumerable#find_map and Enumerable#find_all_map
https://bugs.ruby-lang.org/issues/8421#change-107329

* 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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