Ruby: Dynamic meta-programming to create attr_accessor like methods on the fly

person.rb

class Person
  def initialize(attributes)
    attributes.each do |attribute_name, attribute_value|
      ##### Method one #####
      # Works just great, but uses something scary like eval
      # self.class.class_eval {attr_accessor attribute_name}
      # self.instance_variable_set("@#{attribute_name}", attribute_value)

      ##### Method two #####
      # Manually creates methods for both getter and setter and then 
      # sends a message to the new setter with the attribute_value
      self.class.send(:define_method, "#{attribute_name}=".to_sym) do |value|
        instance_variable_set("@" + attribute_name.to_s, value)
      end

      self.class.send(:define_method, attribute_name.to_sym) do
        instance_variable_get("@" + attribute_name.to_s)
      end

      self.send("#{attribute_name}=".to_sym, attribute_value)
    end
  end
end

This just saved me FOREVER!! Thank you!

Thanks, @davidbella, it's awesome!

Have expanded with methods for creating accessors on other entities - https://gist.github.com/texpert/38f480ed2647f65db5a22f3f98c51fc8

This is awesome, using this and giving you attribution in my documentation. Thank you!

this was super helpful, thx! :)

Helped me as well! Thanks!

Thank you @davidbella! It's an excellent reference to dinamically handle json columns as regular attributes. I just posted an example here:

https://gist.github.com/pangui/28b45c3601395ef52df649a7ef84388b

The gist can also be adapted for Rails ApplicationRecord models via ActiveSupport::Concern