Toggle Light

One button turns a light on, and the next press turns it off again. Put it by a door to light a room.

You need
Code
Wire it
Check it in game
Change it
How it works

You need

a Button
a brick with a Point Light

button Held -> chip pressed
chip light -> light Enabled

Code

const START_ON = false // whether the light is on when the chip is pasted

@left in pressed: exec
var lit: bool = START_ON
@right out light = lit.Value

on pressed {
  lit = !lit
}

Wire it

Compile the chip and paste it in-game. Place the Button and the Point Light.
Wire the Button’s Held to pressed.
Wire light to the Point Light’s Enabled.

Check it in game

Press the button: the light comes on, and stays on after you let go.
Press it again: the light goes off.
Hold the button down: nothing more happens until you let go and press again.

Change it

Start with the light on: set START_ON = true.
Add a second button at the other end of the room. Add @left in pressed2: bool, wire the second Button’s Held to it, make pressed a bool too, and change the handler to on pressed || pressed2. The OR reads both pins’ values, which is why they are bools. A press on one button while the other is held down does nothing: the OR is already on.
Dim the light instead of switching it off: @right out light: float = if lit.Value then 4.0 else 0.5. if A then X else Y gives X while A is true and Y otherwise. Wire light to the Point Light’s Brightness, and leave its Enabled on.

lit is a variable the chip remembers (Remembering Values). on pressed runs once each time the button’s Held turns on, and lit = !lit flips the variable (Pure and Exec). light follows the variable all the time, so the light shows whatever was stored last. Toggles and Latches builds the same part from the game’s Toggle gate, and a latch with separate on and off buttons.

Wirescript