Overriding get_calories: How Python Picks Which Method Runs

When two classes in the same chain both define `get_calories`, how does Python decide which one actually runs?

Finger exercises

Short drills on what this video just taught. Write the code, run the checks, and reveal the answer only if you are stuck.

0 / 5 passed

Exercise 1 of 5

A rate the parent never had

Workout is already defined above, with its class variable cal_per_hr = 200. Complete RunWorkout so it adds a class variable cals_per_km set to 100, and so its constructor lets Workout set up hours before storing the route on the instance as self.route_gps_points. The checks build RunWorkout(2) and RunWorkout(2, points) and read RunWorkout.cals_per_km, hours and route_gps_points.

Given code — runs before yours

class Workout(object):
    cal_per_hr = 200

    def __init__(self, hours):
        self.hours = hours

class RunWorkout(Workout):
    # Add the new class variable here.

    def __init__(self, hours, route_gps_points=None):
        # Let Workout set up hours, then store the route on the instance.
        ...

class RunWorkout(Workout):
    # Add the new class variable here.

    def __init__(self, hours, route_gps_points=None):
        # Let Workout set up hours, then store the route on the instance.
        ...

Python runs in your browser

⌘/Ctrl + Enter runs

carries a per-kilometre rate of its own

still inherits the per-hour rate

a run built without a route stores None

a run built with a route keeps it

←Previous A Subclass Where Its Parent Goes, and Positional Argument Order Next __eq__ With super(), and the Last Word on Building Classes →