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我不完全理解类。我已经阅读了 python 文档和其他几个教程。我了解它的基本要点,但不了解其中的细微差别。例如在我的代码中:

class whiteroom():
    """ Pick a door: red, blue, green, or black. """

    do = raw_input("> ")

    if "red" in do:
        print "You entered the red room."

    elif "blue" in do:
        print "You entered the blue room."

    elif "green" in do:
        print "You entered the green room."

    elif "black" in do:
        print "You entered the black room."

    else:
        print "You sit patiently but slowly begin to stave.  You're running out of time."
        return whiteroom()

game = whiteroom()
game

(原键盘

我想返回课堂白室。这是不可能的,或者没有正确完成。如果您可以弄清楚如何返回一个类或如何将两个类“链接”在一起,以便白色房间在 else 上重复,并且在调用时返回其他房间(这将是类),那就太棒了。

此外,我非常不稳定,__init__仍然不确定它的目的是什么。每个人都一直告诉我它“初始化”,我确信它确实如此,但这似乎并没有帮助我的大脑。

4

6 回答 6

66

函数与类非常不同。看起来你接受了一个函数,只是defclass. 我想这主要适用于你的情况,但这不是课程应该如何进行的。

类包含函数(方法)和数据。例如,你有一个球:

class Ball(object):
    # __init__ is a special method called whenever you try to make
    # an instance of a class. As you heard, it initializes the object.
    # Here, we'll initialize some of the data.
    def __init__(self):
        # Let's add some data to the [instance of the] class.
        self.position = (100, 100)
        self.velocity = (0, 0)

    # We can also add our own functions. When our ball bounces,
    # its vertical velocity will be negated. (no gravity here!)
    def bounce(self):
        self.velocity = (self.velocity[0], -self.velocity[1])

现在我们有一Ball堂课。我们如何使用它?

>>> ball1 = Ball()
>>> ball1
<Ball object at ...>

它看起来不是很有用。数据可能有用:

>>> ball1.position
(100, 100)
>>> ball1.velocity
(0, 0)
>>> ball1.position = (200, 100)
>>> ball1.position
(200, 100)

好吧,很酷,但是与全局变量相比有什么优势?如果您有另一个Ball实例,它将保持独立:

>>> ball2 = Ball()
>>> ball2.velocity = (5, 10)
>>> ball2.position
(100, 100)
>>> ball2.velocity
(5, 10)

并且ball1保持独立:

>>> ball1.velocity
(0, 0)

现在bounce我们定义的那个方法(类中的函数)呢?

>>> ball2.bounce()
>>> ball2.velocity
(5, -10)

bounce方法导致它修改velocity自己的数据。再一次,ball1没有被感动:

>>> ball1.velocity

应用

一个球是整洁的,但大多数人并没有模拟这一点。你在做游戏。让我们想想我们有什么样的东西:

  • 房间是我们能拥有的最明显的东西。

所以让我们开个房间吧。房间有名字,所以我们会有一些数据来存储它:

class Room(object):
    # Note that we're taking an argument besides self, here.
    def __init__(self, name):
        self.name = name  # Set the room's name to the name we got.

让我们举个例子:

>>> white_room = Room("White Room")
>>> white_room.name
'White Room'

漂亮。但是,如果您希望不同的房间具有不同的功能,那么这并不是那么有用,所以让我们创建一个子类。子类从其继承所有功能,但您可以添加更多功能或覆盖超类的功能。

让我们考虑一下我们想要对房间做什么:

我们想与房间互动。

我们如何做到这一点?

用户输入一行得到响应的文本。

它的响应方式取决于房间,所以让我们用一个名为的方法来处理房间interact

class WhiteRoom(Room):  # A white room is a kind of room.
    def __init__(self):
        # All white rooms have names of 'White Room'.
        self.name = 'White Room'

    def interact(self, line):
        if 'test' in line:
            print "'Test' to you, too!"

现在让我们尝试与之交互:

>>> white_room = WhiteRoom()  # WhiteRoom's __init__ doesn't take an argument (even though its superclass's __init__ does; we overrode the superclass's __init__)
>>> white_room.interact('test')
'Test' to you, too!

您最初的示例以在房间之间移动为特色。让我们使用一个名为的全局变量current_room来跟踪我们所在的房间。1让我们也制作一个红色房间。

1. 这里除了全局变量之外还有更好的选择,但为了简单起见,我将使用一个。

class RedRoom(Room):  # A red room is also a kind of room.
    def __init__(self):
        self.name = 'Red Room'

    def interact(self, line):
        global current_room, white_room
        if 'white' in line:
            # We could create a new WhiteRoom, but then it
            # would lose its data (if it had any) after moving
            # out of it and into it again.
            current_room = white_room

现在让我们试试:

>>> red_room = RedRoom()
>>> current_room = red_room
>>> current_room.name
'Red Room'
>>> current_room.interact('go to white room')
>>> current_room.name
'White Room'

读者练习:WhiteRoom在's中添加代码interact,让您回到红色房间。

现在我们已经一切正常,让我们把它们放在一起。有了我们name所有房间的新数据,我们还可以在提示中显示当前房间!

def play_game():
    global current_room
    while True:
        line = raw_input(current_room.name + '> ')
        current_room.interact(line)

您可能还想创建一个函数来重置游戏:

def reset_game():
    global current_room, white_room, red_room
    white_room = WhiteRoom()
    red_room = RedRoom()
    current_room = white_room

将所有类定义和这些函数放入一个文件中,您可以像这样在提示符下播放它(假设它们在 中mygame.py):

>>> import mygame
>>> mygame.reset_game()
>>> mygame.play_game()
White Room> test
'Test' to you, too!
White Room> go to red room
Red Room> go to white room
White Room>

为了能够通过运行 Python 脚本来玩游戏,您可以在底部添加:

def main():
    reset_game()
    play_game()

if __name__ == '__main__':  # If we're running as a script...
    main()

这是对课程的基本介绍以及如何将其应用于您的情况。

于 2012-04-04T04:58:34.427 回答
5

我相信你以前听过这一切,但我会试一试。

类是一种将一堆函数和变量组合成一个对象的方法。当您深入了解它时,这只是一种将所有内容组织成有意义的组的方法。让事情更容易理解、调试、扩展或维护是有好处的,但基本上它只是一种让你的心智模型更明确的方法。

您的代码看起来像是在尝试将整个程序编写在“对象”中(实际上,您只是编写了一个错误的函数)。

考虑一下这个。

想想你的心智模型,房间里有门,里面有白板。门有颜色。此外,白板上可以写一些文字。我们将把它放在那里很简单。

对我来说,这意味着 3 个不同的对象——一个带有颜色字符串的门对象,一个带有文本字符串的白板对象,以及一个带有门和白板的房间对象。

考虑以下代码:

class Door(object):
    def __init__(self, color):
        self.color = color

class Whiteboard(object):
    def __init__(self, default_text=''):
        self.text = ''
        self.write_text(default_text)

    def write_text(self, text):
        self.text += text

    def erase(self):
        self.text = ''


class Room(object):
    def __init__(self, doorcolor, whiteboardtext=''):
        self.whiteboard = Whiteboard(whiteboardtext)
        self.door = Door(doorcolor)




# make a room with a red door and no text on the whiteboard
room1 = Room('red')

# make a room with a blue door and 'yeah, whiteboard' on the whiteboard
room2 = Room('blue', 'yeah, whiteboard')

# make a room with a green door
room3 = Room('green')



# now I can play around with my 'rooms' and they keep track of everything internally

print 'room 1 door color: ' + room1.door.color
print 'room 2 door color: ' + room2.door.color


# all my rooms have a door and a whiteboard, but each one is different and self contained. For example
# if I write on room 1's whiteboard, it doesn't change anything about room 3s

print 'room1 whiteboard: ' + room1.whiteboard.text
print 'room2 whiteboard: ' + room2.whiteboard.text
print 'room3 whiteboard: ' + room3.whiteboard.text

print '-- changeing room 1 whiteboard text --'

room1.whiteboard.write_text('oop is really helpful')


print 'room1 whiteboard: ' + room1.whiteboard.text
print 'room2 whiteboard: ' + room2.whiteboard.text
print 'room3 whiteboard: ' + room3.whiteboard.text

init函数是在您“初始化”类的新实例时调用的函数。在示例中,我制作了 3 个 Room 对象,每个对象在内部创建了一个 Door 和 Whiteboard 对象。我传递给构造函数的参数Room(parameter1, parameter2)被传递给初始化函数——你可以看到我正在使用它来设置门颜色和白板上的一些文本(可选)。另请注意,“属于”对象的变量被引用self- 这个引用是作为所有类函数的第一个参数传入的(并且在您扩展类和其他更高级的东西时变得更加重要)。

于 2012-04-04T04:36:32.970 回答
2

好吧,我从Mark Lutz 的 Learning Python中了解了 Python 中的 OOPS 。它是理解 Python 概念的综合资源,尤其是用于编写Pythonic方式的代码。

为了您的在线参考,我喜欢这个网站的教程。浏览这篇文章,它将帮助您进行初始化。Python 中的 OOP 非常容易理解和实现。起初看起来令人生畏,但在编写了一些基本的 OOP 代码之后就轻而易举了。享受学习。。

于 2012-04-04T04:44:31.210 回答
2

你真的很遥远。

很抱歉这么说,但这几乎是无法挽救的。

据我所知,您想要诸如房间类之类的东西,例如:

class Room(object):
    ''' A generic room '''
    def __init__(self):
        self.choices = None
        self.enter()
    def enter(self):
        ''' Enter the room, to be filled out in subclass '''
        pass
    def print_choices(self):
        '''You are stuck bro'''
        print "You are stuck bro"

然后你可以像这样制作一个特定的房间,比如 whiteroom:

class Whiteroom(Room):
    ''' A white room '''
    def __init__(self):
        self.choices = ["red", "blue", "green", "black"]
        self.enter()
    def enter(self):
        print "You sit patiently, but slowly begin to starve.  You're running out of time."
    def print_choices(self):
        print "You can choose from the following rooms:"
        print self.choices

class Blackroom(Room):
    ''' A black room '''
    def enter(self):
        print "It's really dark in here.  You're out of time."

class Redroom(Room):
    ''' A red room '''
    def __init__(self):
        self.choices = ["black", "blue", "green", "white"]
        self.enter()
    def enter(self):
        print "It's getting hot in here.  So take off all your clothes."
    def print_choices(self):
        print "You can choose from the following rooms:"
        print self.choices

class Blueroom(Room):
    ''' A blue room '''
    def __init__(self):
        self.choices = ["black", "red", "green", "white"]
        self.enter()
    def enter(self):
        print "It's nice and cool in here.  Stay awhile if you want."
    def print_choices(self):
        print "You can choose from the following rooms:"
        print self.choices

class Greenroom(Room):
    ''' A green room '''
    def __init__(self):
        self.choices = ["black", "red", "blue", "white"]
        self.enter()
    def enter(self):
        print "You won."

然后你必须这样做来运行游戏:

print "Type 'quit' to quit"
print "Type 'choices' to see what your choices are"

current_room = Whiteroom()
done = False
while (not done):
    entry = raw_input("> ")
    if entry == "quit":
        done = True
    if "choices" in entry:
        current_room.print_choices()
    if current_room.choices:
        if entry in current_room.choices:    
            if "white" in entry:
                current_room = Whiteroom()

            if "black" in entry:
                current_room = Blackroom()

            if "red" in entry:
                current_room = Redroom()

            if "green" in entry:
                current_room = Greenroom()
                done = True

            if "blue" in entry:
                current_room = Blueroom()

这是我使用类将您的片段变成实际游戏的最佳尝试。

于 2012-04-04T05:10:32.923 回答
1

面向对象编程一开始可能是一件非常有趣的事情,真正了解它的唯一方法是花时间做大量的阅读和练习。一个很好的起点将是在这里。http://www.voidspace.org.uk/python/articles/OOP.shtmlhttp://wiki.python.org/moin/BeginnersGuide/Programmers

于 2012-04-04T04:22:29.157 回答
0

类圆():

pi = 3.14

def __init__(self,radius=1):
    
    self.radius = radius
    self.area = radius*radius*self.pi

def get_circrumference(self):
    return self.radius* self.pi*2
    

结果:圆(23)

my_circle = 圆(30)

my_circle.pi = 3.14

my_circle.radius = 30

my_circle.get_circrumference() = 118.4

my_circle.area = 2826.0

help(Circle) = 模块main中类 Circle 的帮助:

类圈(builtins.object)| 圆(半径=1) |
| 此处定义的方法:|
| 初始化(自我,半径=1)| 初始化自己。请参阅 help(type(self)) 以获取准确的签名。|
| get_circumference(self) |
| -------------------------------------------------- -------------------- | 此处定义的数据描述符:|
| 字典 | 实例变量的字典(如果已定义) |
| 弱引用 | 对象的弱引用列表(如果已定义) |
| -------------------------------------------------- -------------------- | 此处定义的数据和其他属性:|
| 圆周率 = 3.14

于 2021-08-28T11:13:32.853 回答