Question

我有一个正在处理的项目，并且我有一个运行良好的Python类对象，但是我很好奇在调用__init__方法时它是否设计正确。

现在，我有一个函数（demand_curve）在您创建类对象的新实例时将运行。 如果在初始化类时运行一个函数可以吗？还是会让我容易遇到麻烦？

以下是完整的代码供您参考：

# initalize the lists
prices = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
quantities = [13.75, 12.5, 11.25, 10.0, 8.75, 7.5, 6.25, 5.0, 3.75, 2.5, 1.25, 0.0]


class MarketFunction(object):   

    def __init__(self, prices, quantities):

        self.prices = prices
        self.quantities = quantities

        self.intercept = None
        self.slope = None

        # Run the demand_curve function to calculate the slope and the intercept.
        self.demand_curve(prices, quantities)

    @property
    def DemandIntercept(self):
        '''
            SUMMARY: Return the intercept of the demand curve.
            RETURN TYPE: float
        '''

        if self.intercept is None:
            intercept = self.demand_curve(self.prices, self.quantities)
            self.intercept = intercept[0]

        return self.intercept

    @property
    def MaxPrice(self):
        '''
            SUMMARY: Return the maximum price from the Prices list.
            RETURN TYPE: float
        '''
        return max(self.prices)

    @property
    def MinPrice(self):
        '''
            SUMMARY: Return the minimum price from the Prices list.
            RETURN TYPE: float
        '''
        return min(self.prices)

    @property
    def MaxQuantity(self):
        '''
            Summary: Return the maximum quantity from the Quantities list.
            RETURN TYPE: int
        '''
        return max(self.prices)

    @property
    def MinQuantity(self):
        '''
            SUMMARY: Return the minimum quantity from the Quantities list.
            RETURN TYPE: int
        '''
        return min(self.quantities)    


    def demand_curve(self, prices, quantities):
        '''
            SUMMARY: Given an array of prices and quantities calculate the slope and Y-intercept of the line and set the
                     values for the MarketFunction object.

            PARA prices: A list of prices
            PARA TYPE: list

            PARA quantites: A list of quantites
            PARA TYPE: list
        '''

        # grab the first few values.
        x0, x1 = prices[0], prices[1]
        y0, y1 = quantities[0], quantities[1]

        # calculate the metrics
        slope = (y1 - y0)/(x1 - x0)
        y_int = (-slope * x0) + y0

        self.intercept = y_int
        self.slope = slope


# create a new instance of the object    
market = MarketFunction(prices = prices, quantities = quantities)

# Grab the DemandIntercept
demand_function = market.DemandIntercept
demand_function

Answer 1

在__init__中使用函数或方法绝对没有问题。该对象已被分配，而__init__方法正是这样做的，它可以初始化该对象，因此是完全安全的。

在Python中初始化对象类时是否应该运行函数？

1 个答案: