Question

Given the following code:

class MagicList
  def items=(array)
    @items = array.map{|x| x*2}
  end

  def items
    @items
  end
end

list = MagicList.new
returns = list.items=([1, 2, 3])

puts returns.inspect    # => [1, 2, 3]
puts list.items.inspect # => [2, 4, 6]

I expected the value of returns to be [2, 4, 6], because @items as well as array.map{|x| x*2} both return this value. Why is it [1, 2, 3]?

Answer 1

Because Ruby assignments always return the item they were passed, regardless of what the setter= method returns.

See also Is it possible to have class.property = x return something other than x?