将游戏转换为面向对象的版本

Question

我编写了一个简单的主机游戏，允许我在有墙壁和空白的小关卡中移动我的玩家。这一切都是只用几个简单的函数完成的。

我对 Python 比较陌生，但接下来我想学习 OOP，如果我想让这个游戏面向对象，我将如何继续？

我非常了解类和对象，但如果我不理解所有答案，请耐心等待。

这是当前的游戏：

LEVEL = [
    'xxxxxx',
    'x    x',
    'x i  x',
    'x    x',
    'x    x',
    'xxxxxx'
]

def get_block(x, y):
    """Gets a block at the given coordinates."""
    try:
        return LEVEL[y][x]
    except IndexError:
        return None

def set_block(x, y, block):
    """Sets a block at the given coordinates."""
    try:
        LEVEL[y] = LEVEL[y][:x] + block + LEVEL[y][x + 1:]
    except IndexError:
        pass

def get_player_position():
    """Gets player's position."""
    for y, row in enumerate(LEVEL):
        for x, column in enumerate(row):
            if column == 'i':
                return x, y

def set_player_position(x, y):
    """Sets player's position."""
    block = get_block(x, y)
    if block == ' ':
        px, py = get_player_position()
        set_block(px, py, ' ')
        set_block(x, y, 'i')

def main():
    """Entry point for the program."""
    cmd = ''
    while cmd.lower() not in ('quit', 'q'):
        print('n' * 30)
        for row in LEVEL:
            print(row)
        cmd = input('Command: ').lower()
        px, py = get_player_position()
        if cmd == 'w':
            set_player_position(px, py - 1)
        elif cmd == 's':
            set_player_position(px, py + 1)
        elif cmd == 'a':
            set_player_position(px - 1, py)
        elif cmd == 'd':
            set_player_position(px + 1, py)
    print('Bye.')
if __name__ == '__main__':
    main()

Answer 1

你的问题是开放式的，所以很难给出一个包罗万象的答案——所以我所做的是在你现有的代码中识别出一个数据结构，并将其变成一个类。

过去在全局数据数据结构上运行的函数，现在都是类实例的公共方法，该类是唯一允许在名为 _field 的私有属性中更改其中保存的数据的方法。

做这种事情是编写面向对象软件的重要第一步。

希望您发现该示例具有启发性。

class PlayingField(object):
    # Class constants
    PLAYER = 'i'
    EMPTY = ' '
    EDGE = 'x'
    DEFAULT_SIZE = 6
    def __init__(self, size=DEFAULT_SIZE):
        X, EMPTY = self.EDGE, self.EMPTY
        self._size = size
        # build playing field
        self._field = [size*X] + (size-2)*[X + (size-2)*EMPTY + X] + [size*X]
        self._set_block(2, 2, self.PLAYER)  # Initialize player's position.
    def display(self):
        print(30*'n')
        for row in self._field:
            print(row)
    def get_player_position(self):
        """Gets player's position."""
        for y, row in enumerate(self._field):
            for x, column in enumerate(row):
                if column == self.PLAYER:
                    return x, y
        else:
            raise ValueError("Couldn't determine player's location on field")
    def set_player_position(self, x, y):
        """Sets player's position."""
        block = self._get_block(x, y)
        if block == self.EMPTY:
            px, py = self.get_player_position()
            self._set_block(px, py, self.EMPTY)
            self._set_block(x, y, self.PLAYER)

    # Private methods
    def _get_block(self, x, y):
        """Gets a block at the given coordinates."""
        try:
            return self._field[y][x]
        except IndexError:
            return None
    def _set_block(self, x, y, block):
        """Sets a block at the given coordinates."""
        try:
            self._field[y] = self._field[y][:x] + block + self._field[y][x + 1:]
        except IndexError:
            pass
def main():
    """Entry point for the program."""
    field = PlayingField()
    cmd = ''
    while cmd.lower() not in ('quit', 'q'):
        field.display()
        cmd = input('Command: ').lower()
        px, py = field.get_player_position()
        if cmd == 'w':
            field.set_player_position(px, py - 1)
        elif cmd == 's':
            field.set_player_position(px, py + 1)
        elif cmd == 'a':
            field.set_player_position(px - 1, py)
        elif cmd == 'd':
            field.set_player_position(px + 1, py)
    print('Bye.')
if __name__ == '__main__':
    main()