Ruby - 初始化后立即修改Struct属性

Question

假设我有:

Book = Struct.new(:title, :content)
book = Book.new('harry potter', 'a bunch of content here')
p book.title #=> harry potter

最后一行我要制作的是《哈利·波特》。我知道我可以做类似的事情:

Book = Struct.new(:title, :content) do
  def capitalized_title
    self.title.gsub(/\S+/, &:capitalize)
  end
end

然后调用 capitalized_title，但我想要的是不必创建单独的方法，而是有一些方法，当您将“title”分配给新的 Book 对象时，标题会立即大写。我猜是某种钩子(Hook)方法。

Answer 1

class Book < Struct.new(:title, :content)
  def title
    super.gsub(/\S+/, &:capitalize)
  end
end

book = Book.new('harry potter', 'a bunch of content here')
book.title # => "Harry Potter"

---

Book = Struct.new(:title, :content) do
  alias orig_title title
  def title
    orig_title.gsub(/\S+/, &:capitalize)
  end
end

为了防止title每次都被调用，覆盖title=:

Book = Struct.new(:title, :content) do
  alias orig_title= title=
  def initialize(*args)
    super
    self.title = title
  end
  def title= value
    self.orig_title = value.gsub(/\S+/, &:capitalize)
  end
end