Issue #15831 has been updated by matz (Yukihiro Matsumoto).

Status changed from Open to Rejected

I don't think we have seen the use-case that this method is absolutely necessary. I also concern about the name conflict with the ActiveSupport method.

Let me see the real-world use-case, please.

Matz.

----------------------------------------
Feature #15831: Add `Array#extract`, `Hash#extract`, and `ENV.extract`
https://bugs.ruby-lang.org/issues/15831#change-78137

* Author: bogdanvlviv (Bogdan Denkovych)
* Status: Rejected
* 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 for which the block evaluates to +true+.
If no block is given, an Enumerator is returned instead.

```ruby
h = {a: 100, b: 200, c: 300}
h.extract {|k, v| v > 150} # => {:b=>200, :c=>300}
h # => {:a=>100}
```

Note that there is method `extract!` in Active Support that was added in 2009, see
https://github.com/rails/rails/commit/8dcf91ca113579646e95b0fd7a864dfb6512a53b
But I think we should upstream `extract!` to Ruby as `slice!`.


## Add `ENV.extract`

The method removes and returns the key/value pairs for which the block evaluates to +true+.
If no block is given, an Enumerator is returned instead.

```ruby
ENV.extract {|k, v| k == "PORT"} # => {"PORT"=>"3000"}
```


Pull Request: https://github.com/ruby/ruby/pull/2171
Patch: https://patch-diff.githubusercontent.com/raw/ruby/ruby/pull/2171.patch



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