o = Object.new
o.freeze

o.clone.frozen?
#=> true

o.dup.frozen?
#=> false

克隆还将复制对象的单例方法,而dup不会：

o = Object.new
def o.foo
  42
end

o.clone.respond_to?(:foo)
#=> true

o.dup.respond_to?(:foo)
#=> false

这导致我认为克隆有时被理解为提供比dup更“复杂”的假设.这里有一些关于这个主题的引语：

Comment on ActiveRecord::Base#initialize_dup from Rails 3：

Duped objects have no id assigned and are treated as new records. Note
that this is a “shallow” copy as it copies the object’s attributes
only,not its associations. The extent of a “deep” copy is application
specific and is therefore left to the application to implement according
to its need.

@H_404_27@

An article about deep copies in Ruby：

There is another method worth mentioning,clone. The clone method does the same thing as dup with one important distinction: it’s expected that objects will override this method with one that can do deep copies.

@H_404_27@

But then again,theres deep_dup in Rails 4：

Returns a deep copy of object if it’s duplicable. If it’s not duplicable,returns self.

@H_404_27@

and also ActiveRecord::Core#dup and #clone in Rails 4：

clone — Identical to Ruby’s clone method. This is a “shallow” copy. Be warned that your attributes are not copied. […] If you need a copy of your attributes hash,please use the #dup method.

@H_404_27@

这意味着在这里,dup这个词再次被用来指代一个深的克隆.据我所知,在社区中似乎没有共识,只要您需要使用clone和dup,当您需要任何一个特定的副作用时.

最后,我在Ruby代码中看到dup比克隆更多.到目前为止,我从来没有使用过克隆,直到明确需要我才会使用克隆.