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Python

Posted by Federico Isabello
Federico Isabello
1,637 Points

Hi!, I need to start the car in color red and afterwards I have to change it to blue, what is the problem in this code?

class Car():

def __init__(self, brand, color):
    self.brand = brand
    self.color = color
    self.engine_started = False

def start_engine(self):
    self.engine_started = True

def stop_engine(self):
    self.engine_started = False

# Add a method below to change the color of a car
def ch_color(self, color):
    self.color = color

Instantiate a red car and change it to blue

car_red = Car('brand', 'red')


car_red.__initiate__(self, 'brand', 'red')

car_blue = car_red.ch_color('brand', 'blue')
Federico Isabello
Federico Isabello
1,637 Points

I think I got it!

Is the following code correct?

class Car():

def __init__(self, brand, color):
    self.brand = brand
    self.color = color
    self.engine_started = False

def start_engine(self):
    self.engine_started = True

def stop_engine(self):
    self.engine_started = False

# Add a method below to change the color of a car
def ch_color(self, color):
    self.color = color

Instantiate a red car and change it to blue

car_red = Car('brand', 'red')

car_red.init('brand', 'red')

car_blue = car_red.ch_color('blue')

Chris Freeman
Chris Freeman
Treehouse Moderator 68,426 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,426 Points

Pro tip: you can improve post readability by wrapping code in

```python and ```

using backticks (left of 1 on keyboard)

1 Answer

jb30
jb30
44,806 Points

When you run car_red = Car('brand', 'red'), it runs the __init__ method in Car for you. When you run car_blue = car_red.ch_color('blue'), car_red changes its color to 'blue', then returns None, and car_blue is set to None.

car_red = Car('brand', 'red')
car_red.ch_color('blue')
Federico Isabello
Federico Isabello
1,637 Points

Thanks jb !

I change the code for the following, how can I change the return of None that you mention? In this code I tried to see if the blue_car is an instance of the class and return false, if it should be equal to red why is not part of the same class?

class Car():

def __init__(self, brand, color):
    self.brand = brand
    self.color = color
    self.engine_started = False

def start_engine(self):
    self.engine_started = True

def stop_engine(self):
    self.engine_started = False

# Add a method below to change the color of a car
def ch_color(self, color):
    self.color = color

Instantiate a red car and change it to blue

car_red = Car('brand', 'red') car_blue = car_red.ch_color('blue')

print(isinstance(car_blue, Car))

jb30
jb30
44,806 Points

If you want ch_color to have a return value,

def ch_color(self, color):
    self.color = color
    return self