在学习《Python编程：从入门到实践》中类这一章节，其中子类的案例代码如下：
class Car():
--snip--
class Battery():
"""一次模拟电动汽车电瓶的简单尝试"""
def __init__(self, battery_size=70):
"""初始化电瓶的属性"""
self.battery_size = battery_size
def describe_battery(self):
"""打印一条描述电瓶容量的消息"""
print("This car has a " + str(self.battery_size) + "-kWh battery.")
class ElectricCar(Car):
"""电动汽车的独特之处"""
def __init__(self, make, model, year):
""" 初始化父类的属性，再初始化电动汽车特有的属性
"""
super().__init__(make, model, year)
self.battery = Battery()
my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_name())
于是我仿照案例写了如下代码：
class User():
def __init__(self, first_name, last_name):
self.fist_name = first_name
self.last_name = last_name
def describle(self):
print("The uses\'s name is " + str(self.fist_name) + ' ' + str(self.last_name) + '.')
def greet(self):
print('Hello !' + str(self.fist_name) + ' ' + str(self.last_name) + '.')
class Privilege():
def __init__(self, prilege):
self.prilege = prilege
def show_privilege(self):
print("The privilege of the user is " + self.prilege)
class Admin(User):
def __init__(self, first_name, last_name):
User.__init__(self,first_name, last_name)
self.prilege = Privilege()
people1 = Admin('hans', 'D')
people1.prilege.show_privilege()
运行报错如下：
TypeError: __init__() missing 1 required positional argument: 'prilege'
报错原因：
定义将 类Privilege作为Admin属性 定义时没有传参！
而案例中不需要传参是因为定义 类Battery时，其类内部初始化了，没有额外参数的读入
改正后的代码如下：
class User():
snip '''代码段同上'''
class Privilege():
snip '''代码段同上'''
class Admin(User):
def __init__(self, first_name, last_name,prilege): '''读入参数：privilege'''
User.__init__(self,first_name, last_name)
self.prilege = Privilege(prilege) '''此处传入''
people1 = Admin('hans', 'D','adding post') '''加了一个'adding post'''
people1.prilege.show_privilege()
虽然引入了类的概念，但不能忘了函数调用时参数的引用、初始化，这些根本之道
