OOP Python向基类添加一些属性？

Question

我正在用python学习OOP。尝试使用小型控制台应用程序Stock

class Stock(object):

    def __init__(self, stockName, stockLimit, inStock, rentPrice):

        self.stockName  = stockName   # private
        self.stockLimit = stockLimit  # private
        self.inStock    = inStock     # private
        self.rentPrice  = rentPrice   # private

    def inputStock(self, nProduct):

        if(nProduct >= (self.stockLimit - self.inStock)):
            self.inStock = self.stockLimit
        else:
            self.inStock += nProduct 

    def invoice(self, nDay):
        return self.rentPrice * nDay


class StockProduct(Stock):

    def __init__(self, factor):
        # the base-class constructor:
        Stock.__init__(self, stockName, stockLimit, inStock, rentPrice)
        self.factor = factor # Extra for this stock

    def invoice(self, nDay):
        return Stock.invoice(self, nDay) * self.factor

class StockMaterial(Stock):

    def __init__(self,factor):
        # the base-class constructor:
        Stock.__init__(self, stockName, stockLimit, inStock, rentPrice)
        self.factor = factor # Extra for this stock

    def invoice(self,nDay):
        return Stock.invoice(self, nDay)*self.factor

if __name__ == "__main__":

    N = nDay = 0
    myStock = Stock("stock111", 500, 200, 400000)
    N = float(raw_input("How many product into stock: "+str(myStock.stockName)+" ? "))
    myStock.inputStock(N)
    nDay = int(raw_input("How many days for rent : "+str(myStock.stockName)+" ? "))
    print "Invoice for rent the stock: "+str(myStock.stockName)+ " = "+ str(myStock.invoice(nDay))

    StockProduct = StockProduct("stock222",800, 250, 450000, 0.9)

    N = float(raw_input("How many product into stock: "+str(StockProduct.stockName)+" ? "))
    StockProduct.inputStock(N)
    nDay = int(raw_input("How many days for rent : "+str(StockProduct.stockName)+" ? "))
    print "Invoice for rent the stock: "+str(StockProduct.stockName)+ " = "+ str(StockProduct.invoice(nDay))

我有两个问题：

1. 对于我的方法invoice，如何在python中进行方法重载？在

2. 我在子对象中添加了一些属性，收到以下错误消息：

   StockProduct = StockProduct("stock222",800, 250, 450000, 0.9)
   TypeError
   
   error: __init__() takes exactly 2 arguments (6 given)
   

我该怎么办？在

有人能帮我吗？在

提前感谢

Answer 1

1-是的，你可以用python实现方法重载。在

2-您的子类更改了方法签名。你应该声明为

def __init__(self, stockName, stockLimit, inStock, rentPrice, factor):

如果你想用父类的所有参数加上一些额外的参数来构造它。在

Answer 2

1. 派生类中的重载invoice应该可以正常工作。

2. 基类构造函数需要具有所有参数，因此：

   class StockProduct(Stock):
       def __init__(self, stockName, stockLimit, inStock, rentPrice, factor):
           # the base-class constructor:
           Stock.__init__(self, stockName, stockLimit, inStock, rentPrice)
           self.factor = factor
   
       def invoice(self, nDay):
           return Stock.invoice(self, nDay) * self.factor