From: bogdanvlviv@... Date: 2019-05-14T21:24:06+00:00 Subject: [ruby-core:92649] [Ruby trunk Feature#15831] Add `Array#extract`, `Hash#extract`, and `ENV::extract` Issue #15831 has been updated by bogdanvlviv (Bogdan Denkovych). nobu (Nobuyoshi Nakada) wrote: > Why `Array#extract` has no argument but takes a block, while `Hash` and `ENV` are opposite? I implemented those methods to mirror similar behavior as it is in Active Support, but I also feel like we need to discuss more about behavior and signature of those methods: ## About `Array#extract` ```ruby numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] odd_numbers = numbers.extract { |number| number.odd? } # => [1, 3, 5, 7, 9] numbers # => [0, 2, 4, 6, 8] ``` I do believe that this method should mirror the behavior and the method signature of `Array#reject!` https://docs.ruby-lang.org/en/2.6.0/Array.html#method-i-reject-21 since they are similar except one thing - `Array#extract` returns elements for which the block returns a `true` value. Actually "return elements for the block returns a `true` value" is the main reason why I would like to add this method because there could be and [there already are lots of use cases for those methods](https://bogdanvlviv.com/posts/ruby/rails/array-extract-to-activesupport-6-0.html). So I believe this method good as it is. ## About `Hash#extract` and `ENV::extract` First of all, thank you for your question. I also feel `Hash#extract`/`ENV::extract` should receive a block, in other words should mirror the behavior and the method signature o`Hash#reject!`, but return the hash with key/value pairs for which the block returns `true`. There is an example to make it clear: ```ruby h = {a: 100, b: 200, c: 300} h.extract {|k, v| v > 150} # => {:b=>200, :c=>300} h # => {:a=>100} ``` I also feel like we should add `Hash#slice!`(since we have `Hash#slice`) that would behave exactly in the way I proposed to `Hash#extract` initially. ```ruby h = {a: 100, b: 200, c: 300} h.slice!(:a) # => {:a=>100} h # => {:b=>200, :c=>300} h.slice!(:b, :c, :d) # => {:b=>200, :c=>300} h # => {} ``` I would like to work on `Hash#slice!` implementation as well. Let me know what do you think about it. ---------------------------------------- Feature #15831: Add `Array#extract`, `Hash#extract`, and `ENV::extract` https://bugs.ruby-lang.org/issues/15831#change-78011 * Author: bogdanvlviv (Bogdan Denkovych) * Status: Open * Priority: Normal * Assignee: * Target version: ---------------------------------------- ## Add `Array#extract` The method removes and returns the elements for which the block returns a true value. If no block is given, an Enumerator is returned instead. ```ruby numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] odd_numbers = numbers.extract { |number| number.odd? } # => [1, 3, 5, 7, 9] numbers # => [0, 2, 4, 6, 8] ``` This method was added to Active Support as `extract!` in https://github.com/rails/rails/pull/33137 In this post, you can find use cases of this method https://bogdanvlviv.com/posts/ruby/rails/array-extract-to-activesupport-6-0.html ## Add `Hash#extract` The method removes and returns the key/value pairs matching the given keys. ```ruby h = {a: 100, b: 200, c: 300} h.extract(:a) # => {:a=>100} h # => {:b=>200, :c=>300} h.extract(:b, :c, :d) # => {:b=>200, :c=>300} h # => {} ``` This method was added to Active Support as `extract!` in 2009, see https://github.com/rails/rails/commit/8dcf91ca113579646e95b0fd7a864dfb6512a53b ## Add `ENV::extract` The method removes and returns the key/value pairs matching the given keys. ```ruby ENV.extract("PORT", "RAILS_ENV") # => {"PORT"=>"3000", "RAILS_ENV"=>"development"} ``` Pull Request: https://github.com/ruby/ruby/pull/2171 -- https://bugs.ruby-lang.org/ Unsubscribe: