Example of metaprogramming to create an entire class dynamically without `Kernel.eval`

make_me_an_animal_class.rb

def make_me_an_animal_class(name, property)
  klass = Class.new

  klass.class_eval do
    define_method(:initialize) do |attribute|
      instance_variable_set("@#{property}", attribute)
    end
  
    define_method(property) do
      instance_variable_get("@#{property}")
    end
  end

  Object.const_set(name, klass)
  
  klass
end

make_me_an_animal_class("Dog", "age")
make_me_an_animal_class("Cow", "name")

dog = Dog.new(3)
puts dog.age
puts dog.instance_variable_get("@age")

cow = Cow.new("Daisy")
puts cow.name
puts cow.instance_variable_get("@name")