2017-5-16 类

定义一个类：：

class Dog():
def __init__(self,name,age):
self.name = name
self.age = age

def sit(self):
print(self.name.title() + "is now sitting.")

def roll_over(self):
print(self.name.title() + "rolled over!")

my_dog = Dog('while',6)
my_dog.sit()

 

多个实例：

class Dog():
def __init__(self,name,age):
self.name = name
self.age = age

def sit(self):
print(self.name.title() + "is now sitting.")

def roll_over(self):
print(self.name.title() + "rolled over!")

my_dog = Dog('while',6)
your_dog = Dog('zjy',3)

print("my dog name is " + my_dog.name.title() + '.')
print("my dog is " + str(my_dog.age) + "years old")
my_dog.sit()

 

 

使用类和实例：

class Car():
def __init__(self,make,model,year):
self.make = make
self.model = model
self.year = year

def get_descriptive_name(self):
long_name = str(self.year) + ' ' + self.make + ' ' + self.model
return long_name.title()

my_new_car = Car('audi','a4',2016)
print(my_new_car.get_descriptive_name()

 

给属性指定默认值：

class Car():
def __init__(self,make,model,year):
self.make = make
self.model = model
self.year = year
self.odometer_reading = 0

def get_descriptive_name(self):
long_name = str(self.year) + ' ' + self.make + ' ' + self.model
return long_name.title()

def read_odometer_name(self):
print("This car has " + str(self.odometer_reading) + "miles on it.")

my_new_car = Car('audi','a4',2016)
print(my_new_car.get_descriptive_name())
my_new_car.read_odometer_name()

 

修改属性的值：

class Car():
def __init__(self,make,model,year):
self.make = make
self.model = model
self.year = year
self.odometer_reading = 0

def get_descriptive(self):
long_name = str(self.year) + ' ' + self.make + ' ' + self.model
return long_name.title()

def read_odometer_name(self):
print("This car has " + str(self.odometer_reading) + "miles on it.")

def update_odometer(self,mileage):
self.odometer_reading = mileage

my_new_car = Car('audi','a4',2016)
my_new_car.update_odometer(23)
my_new_car.read_odometer()

 

优化：

class Car():
def __init__(self,make,model,year):
self.make = make
self.model = model
self.year = year
self.odometer_reading = 0

def get_descriptive_name(self):
long_name = str(self.year) + ' ' + self.make + ' ' + self.model
return long_name.title()

def read_odometer_name(self):
print("This car has " + str(self.odometer_reading) + "miles on it.")

def update_odometer(self,mileage):


if mileage >= self.odometer_reading:
self.odometer_reading = mileage
else:
print("NONONO")

def increment_odometer(self,miles):
self.odometer_reading += miles

my_new_car = Car('audi','a4',2016)
my_new_car.update_odometer(10000)
my_new_car.read_odometer_name()
my_new_car.increment_odometer(100)
my_new_car.read_odometer_name()

 

继承：

class Car():

def __init__(self,make,model,year):
self.make = make
self.model = model
self.year = year
self.odometer_reading = 0

def get_descriptive_name(self):
long_name = str(self.year) + " " + self.make + " " + self.model
return long_name

def read_odometer(self):
print("这辆车跑了" + str(odometer_reading) + "公里")

def update_odometer(self,mileage):
if mileage >= self.odometer_reading:
self.odometer_reading = mileage
else:
print("里程表错误")

def increment_odometer(self,miles):
self.odometer_reading += miles

class ElectricCar(Car):
"""电动汽车"""
def __init__(self,make,model,year):
'''初始化父类的属性'''
super().__init__(make,model,year)

my_tesla = ElectricCar('tesla','model s',2016)
print(my_tesla.get_descriptive_name())