Practice: Adapting a Celsius Sensor to a Fahrenheit Dashboard

A new sensor with an old dashboard is a natural Adapter, and this exercise asks you to name the participants and write the adapter. The dashboard calls read_fahrenheit() on whatever thermometer it is given. The new sensor, from another supplier, offers only get_celsius(), and neither class may change.

1. Name the target, the adaptee, the adapter you will write, and the client.
2. Write the adapter as an object adapter.
3. With the sensor reading 21.5 °C, say what the dashboard should show, then run it.

class CelsiusSensor:
    def get_celsius(self) -> float:
        return 21.5


class Dashboard:
    def show(self, thermometer) -> None:
        print(f"Temperature: {thermometer.read_fahrenheit():.1f} F")


class FahrenheitAdapter:
    def __init__(self, sensor: CelsiusSensor) -> None:
        self._sensor = sensor

    def read_fahrenheit(self) -> float:
        return self._sensor.get_celsius() * 9 / 5 + 32


Dashboard().show(FahrenheitAdapter(CelsiusSensor()))

Temperature: 70.7 F