class Dry::Core::Memoizable::Memoizer

def define_memoizable(method:)
  module_eval <<~RUBY, __FILE__, __LINE__ + 1
    def #{method.name}(#{to_declaration(method.parameters)})
      key = [Kernel.__method__] + Kernel.local_variables.map { |var| Kernel.eval(var.to_s) }
      if @__memoized__.key?(key)
        @__memoized__[key]
      else
        @__memoized__[key] = super
      end
    end
  RUBY
  if respond_to?(:ruby2_keywords, true)
    ruby2_keywords(method.name)
  end
end

def initialize(klass, names)
  names.each do |name|
    define_memoizable(
      method: klass.instance_method(name)
    )
  end
end

def to_declaration(params, lookup = params.to_h)
  params.map do |type, name|
    case type
    when :req
      name
    when :rest
      "*#{name}"
    when :keyreq
      "#{name}:"
    when :keyrest
      "**#{name}"
    when :block
      "&#{name}"
    when :opt
      lookup.key?(:rest) ? nil : "*args"
    when :key
      lookup.key?(:keyrest) ? nil : "**kwargs"
    else
      raise NotImplementedError, "type: #{type}, name: #{name}"
    end
  end.compact.join(", ")
end