Question

我有一个属性列表。每个属性都将被设置为一个空数组，我想将元素推送到每个数组。

我想出了如何使用instance_variable_set创建动态数组，但我无法将元素推送到它。

这就是我的所作所为：

attributes = ["eye","hair_color","hair_size","hair_type"]
i = 0
attributes.each do |a|
    # Dynamic arrays are created, like: @eye = []
    instance_variable_set("@#{a}", [])
    # My attempt to push element
    "@#{a}".push(i)
    i += 1
end

如何将元素推送到那些动态数组？

Answer 1

instance_variable_get("@#{a}").push(i)将有效

Answer 2

Petr Balaban说得对。我想我也会注意到你可以each_with_index而不是手动设置和递增i：

attributes = ["eye","hair_color","hair_size","hair_type"]

attributes.each_with_index do |a,i|
  # Dynamic arrays are created, like: @eye = []
  instance_variable_set("@#{a}", [])
  # As Petr noted...
  instance_variable_get("@#{a}").push(i)
end

Answer 3

另一种方法是：

attributes = %w|eye hair_color hair_size hair_type|
attributes.each_with_index do |a, idx|
  self.class.send :attr_accessor, a.to_sym
  public_send "#{a}=", idx
  (public_send a) << idx
end

现在您可以通过getter访问这些变量：

hair_size
#⇒ 2

在Rails

3 个答案: