ruby - << 符号绕过 = 在 ruby​​ 中签名吗？

Question

class Book
  attr_accessor :author
  attr_reader :title
  attr_reader :comments
  def initialize(author, title)
    @author = author
    @title = title
    @comments = []
  end
end

book = Book.new("Chuck Palahniuk", "Fight Club")


book.comments << "#{book.title} was a good book" 
book.comments.each do |p|
  puts p
end
# Fight Club was a good book

如果注释方法只是一个 attr_reader 而不是 attr_writer，为什么 << 附加起作用？是因为它绕过了 attr_writer 的 = 符号吗？

Answer 1

带有 << 的声明修改 book.comments 的数组引用，它不会改变book.comments本身。

打印其 object_id之前和之后:

puts book.comments.object_id
book.comments << "#{book.title} was a good book" 
puts book.comments.object_id

您会看到它是同一个对象。

---

与非法语句比较:

book.comments = []