Python：Error = Class'Foo'没有'bar'成员？

Question

我收到一个错误：

AttributeError错误：类型的对象 '店' 有没有属性 '库存'

我的类设置：

class Shop(object): 
    def __init__(self, name, inventory, margin, profit): 
     self.name = name 
     self.inventory = inventory 
     self.margin = margin 
     self.profit = profit 


# Initial inventory including 2 of each 6 models available 
inventory = 12 
# Markup of 20% on all sales 
margin = .2 
# Revenue minus cost after sale 
for bike in bikes.values(): 
    profit = bike.cost * margin 

，我想打印盘点：

print "Mike's Bikes has {} bikes in stock.".format(Shop.inventory) 

但保持相同的错误。我可以把它一起工作：

print "Mike's Bikes has %d bikes in stock." % (inventory) 

，但我试图使开关.format（）

Answer 1

您从未创建过实例的类的，所以Shop.__init__()方法也从未运行。

您的类没有这样的属性;您为Shop类定义的唯一属性是__init__方法本身。

创建类的实例，然后寻找该实例上的属性：

# Initial inventory including 2 of each 6 models available 
inventory = 12 
# Markup of 20% on all sales 
margin = .2 
# Revenue minus cost after sale 
for bike in bikes.values(): 
    profit = bike.cost * margin 

bikeshop = Shop("Mike's Bikes", inventory, margin, profit) 
print "Mike's Bikes has {} bikes in stock.".format(bikeshop.inventory) 

与Shop(....)创建实例，Python中创建的实例，并呼吁该实例上__init__方法。因此，inventory属性已添加到该实例，然后您可以通过bikeshop.inventory访问它。