CODEWITHSUNDEEP
pythonlistclassappend
Red Panda
Red Panda

Reputation: 1

Appending an object from a class into a list in another class

I'm currently working on a task surrounding classes. In this task I have to create a class named "Balls". This class should have a init method that adds a self variable named position. This should be a list for x and y positions. After that I should create another class named System. This class should takes care of the main actions to perform. Then I have to implement a add ball method in System class that appends a Ball object to a class list inside System. Parameters in the method should be x and y.

class Ball:
    def __init__ (self, x, y):
            self.position = [x, y]

ball1 = Ball(3, 6)
print (ball1.position)
ball2 = Ball(5, 8)
print (ball2.position)
ball3 = Ball(4, 4)
print (ball3.position)


class System:
    def __init__(self):
        self.more_balls = []
    def add_balls (self, x, y):
        self.more_balls.append(Ball(x,y))
        
ballx = System()
ballx.add_balls(2, 4)
ballx.add_balls(5,5)
ballx.add_balls(8,8)
ballx.add_balls(2,4)

print (ballx.more_balls)

How will I be able to fix the code. The expected result is that balls get appended into the more_balls list. Here's the output I get:

[3, 6]
[5, 8]
[4, 4]
[<__main__.Ball object at 0x12308eb80>, <__main__.Ball object at 0x12308edf0>,      <__main__.Ball object at 0x12308eeb0>, <__main__.Ball object at 0x12308e1f0>]

Upvotes: 0

Views: 125

Answers (2)

Nja
Nja

Reputation: 489

I think is not responsibility of System class to receive postions and instantiate Ball objects.

So i would do it like this:

class Ball:
    def __init__ (self, x, y):
            self.position = [x, y]

class System:
    def __init__(self):
        self.more_balls = []
    def add_ball (self, ball):
        self.more_balls.append(ball)

ball1 = Ball(3, 6)
print (ball1.position)
ball2 = Ball(5, 8)
print (ball2.position)
ball3 = Ball(4, 4)
print (ball3.position)        

ballHandler = System()
ballHandler.add_ball(ball1)
ballHandler.add_ball(ball2)
ballHandler.add_ball(ball3)

print (ballHandler.more_balls)
print (ballHandler.more_balls[0].position)

Upvotes: 0

Sushil
Sushil

Reputation: 5531

You have made a small mistake in the add_balls function. You forgot to append the position of the Ball object. Here is how you rectify it:

def add_balls(self, x, y):
    self.more_balls.append(Ball(x, y).position)

Thus, here is the full code:

class Ball:
    def __init__(self, x, y):
        self.position = [x, y]


ball1 = Ball(3, 6)
print(ball1.position)
ball2 = Ball(5, 8)
print(ball2.position)
ball3 = Ball(4, 4)
print(ball3.position)


class System:
    def __init__(self):
        self.more_balls = []

    def add_balls(self, x, y):
        self.more_balls.append(Ball(x, y).position)


ballx = System()
ballx.add_balls(2, 4)
ballx.add_balls(5, 5)
ballx.add_balls(8, 8)
ballx.add_balls(2, 4)

print(ballx.more_balls)

Output:

[3, 6]
[5, 8]
[4, 4]
[[2, 4], [5, 5], [8, 8], [2, 4]]

Upvotes: 1

Related Questions