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Python Object-Oriented Python Dice Roller RPG Roller

Radosław Kalina
Radosław Kalina
13,085 Points

Roll method i RPG Roller Challenge

Can somebody explain me how classmethod roll works. this code pass the challenge but I dont understand it.

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 = 2, die_class = D20):
        super().__init__(self)

        for _ in range(size):
            self.append(die_class())

    @classmethod 
    def roll (cls, num_dice):
        return cls(num_dice)


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

1 Answer

Steven Parker
Steven Parker
230,248 Points

A "classmethod" is mainly different from a normal method in that when you call it, you use the class itself instead of an instance of the class. It's particularly handy here, since "roll" is going to create a new instance and return it.

Examples:

myhand = Hand.roll(2)  # using the class itself to call "roll"
spots = myhand.total   # but "total" is called on the instance