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Python

Posted by Bruce McMinn
Bruce McMinn
10,030 Points

Master Class Q2, how to change attribute on instance

Hi. I'm supposed to be changing the fuel_remaining attribute for the instance I create. When I run this in the console I can return a lowered fuel_remaining value, but it's not changing the instance.

class RaceCar:
    laps = 0

    def __init__(self, color, fuel_remaining, **kwargs):
        self.color = color
        self.fuel_remaining = fuel_remaining

        for key, value in kwargs.items():
            setattr(self, key, value)

    def run_lap(self, length):
        RaceCar.laps += 1
        return(self.fuel_remaining - (0.125 * length))

i.e. if I create an instance with the fuel_remaining as 5 then run a lap of 3, I get 4.625 returned. But if I then type instance.fuel_remaining I still get the original 5.

1 Answer

Bruce McMinn
Bruce McMinn
10,030 Points

Oh, I realized my mistake.

    def run_lap(self, length):
        RaceCar.laps += 1
        self.fuel_remaining = self.fuel_remaining - (0.125 * length)

In the method I hadn't saved the fuel_remaining value. This allows it to apply outside of that particular instantiation. Cool!