introspection - Fastest/One-liner way to list attr_accessors in Ruby?

Question

What's the shortest, one-liner way to list all methods defined with attr_accessor? I would like to make it so, if I have a class MyBaseClass, anything that extends that, I can get the attr_accessor's defined in the subclasses. Something like this:

class MyBaseClass < Hash
  def attributes
    # ??
  end
end

class SubClass < MyBaseClass
  attr_accessor :id, :title, :body
end

puts SubClass.new.attributes.inspect #=> [id, title, body]

What about to display just the attr_reader and attr_writer definitions?

Answer 1

Extract the attributes in to an array, assign them to a constant, then splat them in to attr_accessor.

class SubClass < MyBaseClass
  ATTRS = [:id, :title, :body]
  attr_accessor(*ATTRS)
end

Now you can access them via the constant:

puts SubClass.ATTRS #=> [:id, :title, :body]