! someobject.foo? -> someobject.not_foo?

autonot.rb

# inspired by http://www.msng.info/archives/2012/12/php-not.php

module AutoNot
  def method_missing(method, *args)
    if /\Anot_(.*\?)\z/ =~ method
      ! send($1, *args)
    end
  end
end

foo = ''
foo.extend AutoNot
p foo.not_empty?                #=> false

bar = 'aaa'
bar.extend AutoNot
p bar.not_empty?                #=> true