Events: When This, Do That!
How does a game know you pressed a key?
Real Python code
This is the code from the video. Read it out loud like a recipe, one line at a time!
import turtle
def wave():
turtle.write("Hi!")
turtle.forward(40)
turtle.onkey(wave, "space")
turtle.listen()
turtle.done()Quiz time!
Which key makes jump run?
def jump():
turtle.forward(50)
turtle.onkey(jump, "Up")
turtle.listen()Where events hide
Games
Press a key, and your hero jumps
Send buttons
Click Send, and your message goes
Screens
Tap a picture, and it opens up big
Timers
When time is up, the alarm rings
What we learned
The event
- Something happens
- A click, a key, a timer
- Hat block or onkey
The handler
- The code that answers
- Waits until it's needed
- Runs every time
When this happens, do that!
Try it yourself!
In Scratch, make a sprite say hi when you click it, and wave when you press space.
Bit is working on the next one: If / else: pick a path
