How to get attributes that were defined through attr_reader or attr_accessor

Question

Suppose I have a class A

class A
  attr_accessor :x, :y

  def initialize(x,y)
    @x, @y = x, y
  end
end

How can I get

Answer 1

If you have attr_writers/attr_accessors defined on your attributes, than they can be easily retrieved by matching the =$ regexp:

A.instance_methods.each_with_object([]) { |key, acc| acc << key.to_s.gsub(/=$/, '') if key.match(/\w=$/) }

OR

A.instance_methods.each_with_object([]) { |key, acc| acc << key if key = key.to_s.match(/^(.*\w)=$/)&.[](1) }