有多少种方法可以添加到 ruby 对象中？

发布于 2024-11-15 00:51:33 字数 579 浏览 4 评论 0原文

当谈到运行时自省和动态代码生成时，我认为除了某些 lisp 方言之外，Ruby 没有任何竞争对手。有一天，我正在做一些代码练习来探索 ruby 的动态功能，我开始想知道向现有对象添加方法的方法。以下是我能想到的 3 种方法：

obj = Object.new

# add a method directly
def obj.new_method
  ...
end

# add a method indirectly with the singleton class
class << obj
  def new_method
    ...
  end
end

# add a method by opening up the class
obj.class.class_eval do
  def new_method
    ...
  end
end

这只是冰山一角，因为我还没有探索 instance_eval、module_eval 和 define_method< 的各种组合。 /代码>。是否有在线/离线资源可以让我了解有关此类动态技巧的更多信息？

原文

When it comes to run time introspection and dynamic code generation I don't think ruby has any rivals except possibly for some lisp dialects. The other day I was doing some code exercise to explore ruby's dynamic facilities and I started to wonder about ways of adding methods to existing objects. Here are 3 ways I could think of:

obj = Object.new

# add a method directly
def obj.new_method
  ...
end

# add a method indirectly with the singleton class
class << obj
  def new_method
    ...
  end
end

# add a method by opening up the class
obj.class.class_eval do
  def new_method
    ...
  end
end

This is just the tip of the iceberg because I still haven't explored various combinations of instance_eval, module_eval and define_method. Is there an online/offline resource where I can find out more about such dynamic tricks?

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

迟到的我 2024-11-22 00:51:33

Ruby 元编程似乎是一个很好的资源。（并且，从那里链接到The Book of Ruby。）

回复收藏 0 原文

一笑百媚生 2024-11-22 00:51:33

如果 obj 有一个超类，您可以使用 define_method 从超类向 obj 添加方法 (API) 正如您提到的。如果您查看过 Rails 源代码，您会发现他们做了很多这样的事情。

另外，虽然这并不完全是您所要求的，但您可以轻松地给人留下通过使用 method_missing 动态创建几乎无限数量的方法的印象：

def method_missing(name, *args)
  string_name = name.to_s
  return super unless string_name =~ /^expected_\w+/
  # otherwise do something as if you have a method called expected_name
end

将其添加到您的类中将允许它响应任何方法调用看起来像

@instance.expected_something

If obj has a superclass, you can add methods to obj from the superclass using define_method (API) as you mentioned. If you ever look at the Rails source code, you'll notice that they do this quite a bit.

Also while this isn't exactly what you're asking for, you can easily give the impression of creating an almost infinite number of methods dynamically by using method_missing:

def method_missing(name, *args)
  string_name = name.to_s
  return super unless string_name =~ /^expected_\w+/
  # otherwise do something as if you have a method called expected_name
end

Adding that to your class will allow it to respond to any method call which looks like