Ruby中Array＃map的隐式返回值

Question

给出以下代码：

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]

我预计returns的值为[2, 4, 6]，因为@items和array.map{|x| x*2}都会返回此值。为什么是[1, 2, 3]？

Answer 1

因为Ruby赋值总是返回它们传递的项，无论setter=方法返回什么。

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