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Python Object-Oriented Python Dice Roller RPG Roller

Eric Shelby
Eric Shelby
28,300 Points
Posted by Eric Shelby
Eric Shelby
28,300 Points

RPG Roller Confusion

I need help figuring out challenge out.

"Now update Hand in hands.py. I'm going to use code similar to Hand.roll(2) and I want to get back an instance of Hand with two D20s rolled in it. I should then be able to call .total on the instance to get the total of the two dice."

I states that it can't get the length of a Hand. I'm not sure what I'm missing. A few hints would be appreciated.

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 
from dice import D20

class Hand(list):
    def __init__(self, size = 0, die_class = None, *args, **kwargs):
        super().__init__()

    @property
    def total(self):
        return sum(self)

    def roll(self, size, die_class, numdice):
        size = 2
        die_class = D20
        self.total()

4 Answers

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,441 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,441 Points

The method roll needs to be a classmethod so that it can be access directly from the class Hand.roll(). It should accept only one argument beyond the cls placeholder: the number of die to be in the hand. Using this number, generated an instance of Hand with the correct number of D20 instances in it, then return the hand.

Post back if you need more help. Good Luck!!

Eric Shelby
Eric Shelby
28,300 Points
Eric Shelby
Eric Shelby
28,300 Points

Chris, I came up with this for now, but there are a few gaps that need to be filled in. Any hints:

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

[MOD: added ```python formatting -cf]

Chris Freeman
Chris Freeman
Treehouse Moderator 68,441 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,441 Points

You are close. You need to create an instance using cls() then append to that instance. Finally, return the instance itself after the loop. You do not need to call total yourself.

Eric Shelby
Eric Shelby
28,300 Points
Eric Shelby
Eric Shelby
28,300 Points

Chris, you say I need to create an instance using cls(), but I'm afraid I don't know how to do that. All the examples I looked through have not been of any help.

Eric Shelby
Eric Shelby
28,300 Points
Eric Shelby
Eric Shelby
28,300 Points

Thanks for all your help. I finally solved it. You were right about the creation of an instance. I need to remember that next time.