IPAddr#set

# File tmp/rubies/ruby-4.0.0/lib/ipaddr.rb, line 570
def set(addr, *family)
  case family[0] ? family[0] : @family
  when Socket::AF_INET
    if addr < 0 || addr > IN4MASK
      raise InvalidAddressError, "invalid address: #{addr}"
    end
  when Socket::AF_INET6
    if addr < 0 || addr > IN6MASK
      raise InvalidAddressError, "invalid address: #{addr}"
    end
  else
    raise AddressFamilyError, "unsupported address family"
  end
  @addr = addr
  if family[0]
    @family = family[0]
    if @family == Socket::AF_INET
      @mask_addr &= IN4MASK
    end
  end
  return self
end