OOP in Ruby without classes

001-main.rb

leandro = new_instance(Account, "Leandro", 0)
john    = new_instance(Account, "John", 100)

send_message(leandro, :deposit, 50)
send_message(john, :deposit, 10)

send_message(leandro, :print_balance)
# => Leandro's balance: 50

send_message(john, :print_balance)
# => John's balance: 110

account.rb

Account = {
  properties: [:name, :balance],
  methods: {
    deposit: lambda do |context, amount|
      context[:state][:balance] += amount
    end,
    print_balance: lambda do |context|
      name    = context[:state][:name]
      balance = context[:state][:balance]

      puts "#{name}'s balance: #{balance}"
    end
  }
}

oop_engine.rb

def new_instance(template, *args)
  state =
    template[:properties]
    .zip(args)
    .to_h
  
  template.merge(state: state)
end

def send_message(object, message, *args)
  return unless object[:methods].has_key?(message)
                                                  
  object[:methods][message].call(object, *args)
end