This make class-level method "cached" what makes that method cachable

1.rb

module CachableMethod

  def cachable(merhod_name)
    #aliased_merhod_name = :"uncached_#{merhod_name}"
    #alias_method aliased_merhod_name, merhod_name

    method_proc = instance_method(merhod_name)
    ivar_name = :"@#{merhod_name}"
    define_method(merhod_name) do |*args, &proc|
      if instance_variable_defined?(ivar_name)
        instance_variable_get(ivar_name)
      else
        value = method_proc.bind(self).call(*args, &proc)
        instance_variable_set(ivar_name, value)
        value
      end
    end
  end

  def accepts(*types)
    # this proc should be called with symbol of new method
    Proc.new do |method_name|
      method_proc = instance_method(method_name)
      define_method(method_name) do |*args, &proc|
        types.each_with_index do |type, arg_i|
          unless args[arg_i].kind_of?(type)
            raise ArgumentError.new("Argument num #{arg_i} is type of: #{args[arg_i].class.name}, but must be #{type.name}")
          end
        end # types.each
        method_proc.bind(self).call(*args, &proc)
      end # define_method
    end # Proc.new
  end

  def returns(type)
    # this proc should be called with symbol of new method
    Proc.new do |method_name|
      method_proc = instance_method(method_name)
      define_method(method_name) do |*args, &proc|
        value = method_proc.bind(self).call(*args, &proc)
        unless value.kind_of?(type)
          raise ArgumentError.new("method :#{method_name} returns type #{value.class.name} but must #{type.name}")
        end
        value
      end # define_method
    end # Proc.new
  end
end

class Something
  extend CachableMethod

  accepts(String, Numeric).call \
  returns(Time).call \
  cachable \
  def time(a, b)
    puts "getting a time"
    Time.now
  end
end

s = Something.new
p s.time("a", 4)
p s.time("a", 5)
p s.time("a", []) # => this will raise error ArgumentError, type mismatch
p s



class Fee
  private :method_name
  private def bar
    
  end
end