Python类和方法

Question

我有一些在线的Python编程练习题。现在我卡在了一个问题上：

Write the definition of a class WeatherForecast that provides the following behavior (methods):
A method called set_skies that has one parameter, a String.
A method called set_high that has one parameter, an int.
A method called set_low that has one parameter, an int.
A method called get_skies that has no parameters and that returns the value that was last used as an argument in set_skies .
A method called get_high that has no parameters and that returns the value that was last used as an argument in set_high .
A method called get_low that has no parameters and that returns the value that was last used as an argument in set_low .
No constructor need be defined. Be sure to define instance variables  as needed by your "get"/"set" methods. 

我有这个答案，但我不知道问题出在哪里。系统一直告诉我某个地方的值不正确。

class WeatherForecast (object):
    def __init__ (self):
        self.skies = ''
        self.high = ''
        self.low  = ''
    def set_skies (self, value):
        self.skies = value
    def set_high (self, value):
        self.high = value
    def set_low (self):
        self.low = low
    def get_skies (self):
        return self.skies
    def get_high(self):
        return self.high
    def get_low(self):
        return self.low

Answer 1

我觉得你在 set_low 这个函数里缺少了一个参数。

def set_low (self, value):
    self.low = value

Answer 2

比如，在这个方法里：

def set_high(self, value):    
    self.high = high

你试图把high的值赋给self.high，但是你没有说明high是从哪里来的，程序里只有一个叫value的变量。所以你应该这样修改：

def set_high(self, high):
    self.high = high

Answer 3

这个问题很可能是因为高和低应该是整数。

class WeatherForecast:
    def __init__(self):
        self.__skies=""
        self.__high=0
        self.__low=0

    def set_skies(self, skies):
        self.__skies=skies

    def set_high(self,high):
        self.__high=high

    def set_low(self,low):
        self.__low=low

    def get_skies(self):
        return self.__skies

    def get_high(self):
        return self.__high

    def get_low(self):
        return self.__low

Answer 4

你从来没有定义过 skies、high 或 low 这些东西。

也许在你设置这些东西的函数里，你的意思是：

def set_high (self, value):  # Do this for all setting functions.
    self.high = value  # value is defined, so will work.