GoKawiilBack in 2015, I had the idea for gpiozero — a Python library for Raspberry Pi, making programming GPIO devices simpler by abstraction: instead of thinking about pin channels, voltages, pull-up resistors and rising or falling edges, we think about buttons being pressed and released, sensors detecting light or motion, and motors driving forwards and backwards. gpiozero let you write code in these terms.
We developed a device-focused API, and patterns emerged. We ended up supporting three types of programming:
Procedural:
while True : if button . is_pressed : led . on () else : led . off ()
Event-based:
button . when_pressed = led . on button . when_released = led . off
Declarative:
led . source = button
These three snippets achieve the same thing in different ways. One repeatedly asks the button if it is pressed; one tells the button to control the LED; and one tells the LED to follow the button's state.
It's hard to say which one is easier to read, write or understand. Maybe the last one, since it's a single line. But if you wanted to reverse the logic, and make the button turn the LED off instead of on, it would be trivial to work out how to change the first two, but not the third.
... continue reading