Python Object-Oriented Python Dice Roller RPG Roller

Jimmy Sweeney
Jimmy Sweeney
5,649 Points

What am I doing wrong? RPG roller challenge.

I'm getting an error: TypeError: descriptor 'append' for 'list' objects doesn't apply to a 'int' object

If I change this line in the roll method:

cls.append(D20().value)

to

cls.append(D20())

I get the same error.

dice.py
import random


class Die:
    def __init__(self, sides=2):
        if sides < 2:
            raise ValueError("Can't have fewer than two sides")
        self.sides = sides
        self.value = random.randint(1, sides)

    def __int__(self):
        return self.value

    def __add__(self, other):
        return int(self) + other

    def __radd__(self, other):
        return self + other


class D20(Die):
    def __init__(self):
        super().__init__(sides=20)
hands.py
class Hand(list):
    @property
    def total(self):
        return sum(self)

    @classmethod
    def roll(cls, size):
        for _ in range(size):
            cls.append(D20().value)
        return cls

2 Answers

Steven Parker
Steven Parker
202,109 Points

You were right to remove the ".value", but there are a few other issues:

  • you need to import D20 from the other file
  • "cls" represents the class, you need to create an instance yourself
  • it will the be instance that you append to and finally return
Jimmy Sweeney
Jimmy Sweeney
5,649 Points

"cls" represents the class, you need to create an instance yourself it will the be instance that you append to and finally return

Got it! Thank you! I actually had tried that earlier but I was getting confused because

new_hand = Hand()
new_hand.role(2)

would result in new_hand being an empty list. To contrast:

new_hand = Hand.role(2)

results in a list with 2 random numbers between 1 and 20 (just like it is supposed to). I think I understand the reasoning... "roll" is a class method and can only be "done" (what is the right word to use here? "called on"?) on the class not on an object of the class. Let me know if that is accurate.

Steven Parker
Steven Parker
202,109 Points

That's exactly right. Glad I could help, and happy coding!