class Array

numbers # => [0, 2, 4, 6, 8]
odd_numbers = numbers.extract! { |number| number.odd? } # => [1, 3, 5, 7, 9]
numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

If no block is given, an Enumerator is returned instead.
Removes and returns the elements for which the block returns a true value.

def extract!
  return to_enum(:extract!) { size } unless block_given?
  extracted_elements = []
  reject! do |element|
    extracted_elements << element if yield(element)
  end
  extracted_elements
end