Simply-Simple Auto Lightswitch

Make an auto lightswich turner on thing without technology. I know that slideshow is of drawn pics, but the idae is clear.

Materials:
string (the sturdier the better)
thumbtack or screw with loop ( the screw will be in slideshow)
tape or other sticky thing that wont tear off with pressure
door
lightswitch

when the door opens, the lightswitch is turned on by the string, but you have to turn off the light when you leave the room