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Python Object-Oriented Python Dice Roller RPG Roller

Liang Junwen
Liang Junwen
582 Points
Posted by Liang Junwen
Liang Junwen
582 Points

Sorry, I have no idea about how to finish task 2. Could anyone help? Thankyou.

Sorry, I have no idea about how to finish task 2. Could anyone help? Thankyou. Here is my code, but the hands.py not work.

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):
        super().__init__()

    @classmethod
    def roll(cls, sizes=2, die_class=D20):
        for _ in range(sizes):
            cls.append(die_class())
        return cls

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

1 Answer

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

You're close, but you can't call "append" on the class constructor ("cls"). But you could create a new instance using the constructor first, and then call "append" on that new instance.

It's also not necessary to override "__init__".

Liang Junwen
Liang Junwen
582 Points
Liang Junwen
Liang Junwen
582 Points

Hi Steven, your reply inspires me. I figure out the correct answer:

class Hand(list):
    @classmethod
    def roll(cls, sizes=2, die_class=D20):
        rolls = cls()
        for _ in range(sizes):
            rolls.append(die_class())
        return cls(rolls)

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

Thank you!

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

Good job. But you don't need to call "cls" the second time. Just return "rolls" directly:

        rolls = cls()
        # ...
        return rolls  # rolls is already a class instance

OR you could just set up "rolls" as a plain list:

        rolls = []
        # ...
        return cls(rolls)  # convert the plain list into a class instance
Liang Junwen
Liang Junwen
582 Points
Liang Junwen
Liang Junwen
582 Points

It is a very helpful explanation! Thanks again.