ruby - 在 ruby​​ 中连接它们之间的对象的最佳实践

Question

我无法在纯 ruby​​ 脚本中找到一种很好的方法来实现导航轨道对象的轨道行为。

假设我有一个 Parent 类的对象，有一个 Child 类对象数组的访问器，我希望在操作 Child 对象时能够轻松获得 Parent，就像这样:

class Parent
  attr_accessor :children

  def initialize
    @children = Array.new
  end
end

class Child
end

parent = Parent.new
first_child = Child.new
second_child = Child.new
parent.children << [ first_child, second_child ]

a_child = parent.children.first

get_parent_from_child = a.child.parent

当然，我感兴趣的部分是最后一行，我试图从其中一个子对象获取“父”对象。

我怎样才能轻松干净地实现它？

我正在考虑为子对象添加访问器，但我不确定每次将子对象附加到父对象时如何确保设置此值。

在 ruby​​ 中是否有一种简单干净的方法来做到这一点？

提前致谢。

Answer 1

您不必完全公开您的 child ，您知道，完全控制对您数据的访问并没有错。

class Parent
  def initialize
    @children = [ ]
  end

  # You get a shallow copy of the children, you can
  # change the individual children but not the tree
  # structure.
  def children
    @children.dup
  end

  # We take ownership of the children when you add them.
  def add_children(*kids)
    kids.each { |k| k.parent = self }
    @children += kids
  end

  def remove_children(&block)
    @children.delete_if(&block)
  end
end

# This would probably have some sort of payload and
# a sensible "==" implementation.
class Child
  attr_reader :parent
  def parent=(p)
    raise StandardError => 'Not allowed to change parents!' if @parent
    @parent = p
  end
end

然后 child.parent 工作正常，如果你想删除 child ，你会告诉 parent 删除哪些:

# Remove the children with even payloads.
parent.remove_children { |c| c.payload % 2 == 0 }

# Remove the children with odd payloads and copy them.
odds = [ ]
parent.remove_children do |c|
  kill_it = c.payload % 2 != 0
  odds << Child.new(c.payload) if(kill_it)
  kill_it
end