An example of implementing #to_json for Ruby IRC

waffle.rb

require 'json'

class Waffle
  def initialize(toppings:, syrup:)
    @toppings = toppings
    @syrup = syrup
  end

  class << self
    def json_create(object)
      toppings, syrup = object.values_at('t', 's')

      new(toppings:, syrup:)
    end
  end

  def as_json(*)
    { 
      JSON.create_id => self.class.name,
      't' => @toppings,
      's' => @syrup
    }
  end

  def to_json(*) = as_json(*).to_json(*)
end

waffle = Waffle.new(
  toppings: ['strawberries', 'whipped cream'],
  syrup: 'maple',
)

json = waffle.to_json
#=> "{\"json_class\":\"Waffle\",\"t\":[\"strawberries\",\"whipped cream\"],\"s\":\"maple\"}"

pp JSON.unsafe_load(json)
#=> #<Waffle:0x0 @syrup="maple", @toppings=["strawberries", "whipped cream"]>