Ruby Automatic Unegation

automatic_unegation.rb

module AutomaticUnegation
  def method_missing(name, *args, &block)
    return super unless unegated = unegated_method_name(name)
    !send(unegated, *args, &block)
  end

  def respond_to?(name, include_private = false)
    super || unegated_method_name(name) != nil
  end

  private

  def unegated_method_name(name)
    name = name.to_s
    return unless name.start_with?('not_') && name.end_with?('?')
    unegated = name[4..-1].to_sym
    return unegated if respond_to?(unegated)
  end
end

class Object
  include AutomaticUnegation
end

string = "Hello world"
messages = [
  :not_nil?,
  :not_empty?,
  :not_ascii_only?,
  [:not_include?, 'world'],
  [:not_respond_to?, :not_nil?],
  :not_not_unicode_normalized?,
]
for message in messages
  puts "#{[*message]} → #{string.send(*message)}"
end

# [:not_nil?] → true
# [:not_empty?] → true
# [:not_ascii_only?] → false
# [:not_include?, "world"] → false
# [:not_respond_to?, :not_nil?] → false
# [:not_not_unicode_normalized?] → true