What should I implement to have a custom class behave exactly as an array?

Say I have a custom class, what should I override to get array-like behaviour? I think that supplying an each method开发者_Go百科 won't be enough, as that won't give me acces to the [] methods?

Should I inherit the Array class? What should I overwrite in there?

For enumerable like behavior (which sounds like what you want), you should include Enumerable to get the Enumerable module functionality, which means you need to provide a method each. This will give you lots of the relevant methods you want (Enumerable details).

If you want just [] like functionality, you only need the following methods, and nothing more:

def [] key
  # return value for key here.
end

def []= key, value
  # store value under key here.
end

Inheriting from Array makes perfect sense. You get to extend Array behavior without worrying about interactions with other users of the Array type, and you don't even need to do the trivial work to mix in Enumerable.

And if you need hooks, which you probably do, you can just call super() to forward the current message.

If you have an actual array that stores your data, you may want to have

require "forwardable"

class CustomArray
  extend Forwardable # For def_delegators
  include Enumerable # Optional

  def_delegators :@actual_array, :[], :[]=, :each

  def initialize(actual_array)
    @actual_array = actual_array
  end
end

By using delegation, you only provide the methods that you know you want, rather than providing all the methods by default.