Is there a ruby idiom for popping items from an array while a condition is true

Question

Is there a Ruby idiom for popping items from an array while a condition is true, and returning the collection?

I.e,

# Would pop all negative numbers from the end of 'array' and place them into 'result'.
result = array.pop {|i| i < 0} 

From what I can tell, something like the above doesn't exist.

I'm currently using

result = []
while array.last < 0 do
  result << array.pop
end

Answer 1

Maybe you are looking for take_while?

array = [-1, -2, 0, 34, 42, -8, -4]
result = array.reverse.take_while { |x| x < 0 }

result would be [-8, -4].

To get the original result back you could use drop_while instead.

result = array.reverse.drop_while { |x| x < 0 }.reverse

result would be [-1, -2, 0, 34, 42] in this case.

Answer 2

You could write it yourself:

class Array
  def pop_while(&block)
    result = []
    while not self.empty? and yield(self.last)
      result << self.pop
    end
    return result
  end
end

result = array.pop_while { |i| i < 0 }