我如何摆脱 Python 中的全局变量？

Question

在此示例中，如果我将注释代码换出，global 变量将正常工作。我似乎无法在这里了解有关 Python 的一些基本知识，因为传递变量似乎无法正常工作。

import random

def roll_die(sides=6):
    return random.randint(1, sides)

# def game():
def game(score_p1,score_p2,rounds):

    # global score_p1
    # global score_p2
    # global rounds
    
    roll_1=roll_die()
    roll_2=roll_die()
    winner=None
    if roll_1 > roll_2:
        score_p1 = score_p1 +1
        score_p2 = score_p2 -1
        winner='player 1'
    if roll_1 < roll_2:
        score_p1 = score_p1 -1
        score_p2 = score_p2 +1
        winner='player 2'
    if roll_1 == roll_2:
        winner='No one'
    print(f'p1 rolled {roll_1} and p2 rolled {roll_2}: Winner is {winner} ')    
    print(score_p1,score_p2)
    rounds = rounds + 1
    # print(score_p1,score_p2, rounds)
    return score_p1,score_p2,rounds

if __name__  == '__main__':
    
    tokens=5
    score_p1=tokens
    score_p2=tokens
    rounds=0

    while True:
        if (score_p1 <= 0) or (score_p2 <= 0):
            print(f'Final Score: {score_p1}:{score_p2} with {rounds} rounds')
            break
        else:
            # game()
            game(score_p1,score_p2,rounds)

我从 非全局 版本获得的示例结果：

p1 rolled 3 and p2 rolled 1: Winner is Player 1
6 4
p1 rolled 1 and p2 rolled 4: Winner is Player 2
4 6
p1 rolled 5 and p2 rolled 3: Winner is Player 1
6 4
p1 rolled 3 and p2 rolled 1: Winner is Player 1
6 4
p1 rolled 4 and p2 rolled 4: Winner is No one
5 5
p1 rolled 2 and p2 rolled 2: Winner is No one
5 5

...游戏永远循环

Answer 1

您必须将game 返回的值重新分配给名称：

while True:
    if (score_p1 <= 0) or (score_p2 <= 0):
        print(f'Final Score: {score_p1}:{score_p2} with {rounds} rounds')
        break
    else:
        score_p1, score_p2, rounds = game(score_p1,score_p2,rounds)

Answer 2

一种解决方案是将这些变量存储在一个对象中，以便它们在函数调用之间持续存在——例如，您的所有游戏状态都可以存在于 Game 对象中，如下所示：

import random


def roll_die(sides=6):
    return random.randint(1, sides)


class Game:
    def __init__(self):
        self.tokens = self.score_p1 = self.score_p2 = 5
        self.rounds = 0

    def play(self):
        roll_1 = roll_die()
        roll_2 = roll_die()
        if roll_1 > roll_2:
            self.score_p1 += 1
            self.score_p2 -= 1
            winner = 'player 1'
        elif roll_1 < roll_2:
            self.score_p1 -= 1
            self.score_p2 += 1
            winner = 'player 2'
        else:
            winner = 'No one'
        print(f'p1 rolled {roll_1} and p2 rolled {roll_2}: Winner is {winner} ')
        print(self.score_p1, self.score_p2)
        self.rounds += 1


if __name__ == '__main__':
    game = Game()
    while True:
        game.play()
        if game.score_p1 <= 0 or game.score_p2 <= 0:
            print(f'Final Score: {game.score_p1}:{game.score_p2} with {game.rounds} rounds')
            break