Python编程从入门到实践~类

最新推荐文章于 2025-11-23 20:03:02 发布

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本文介绍了Python中的面向对象编程，包括如何创建类、实例化对象、访问属性和调用方法。通过`Dog`和`Car`类展示了类的构造函数`__init__`，以及如何定义和调用方法如`sit()`和`roll_over()`。此外，还演示了如何通过`update_odometer()`方法更新汽车的里程读数。进一步讨论了类的继承，例如`ElectricCar`类从`Car`类继承并添加了`describe_battery()`方法和覆盖了`fill_gas_tank()`方法。最后，讲解了如何导入已定义的类。

创建Dog 类

方法__init__()，Python 自动调用，约定！！！


#创建Dog 类
class Dog:

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

	def sit(self):
		print(f"{self.name} is now sitting.")

	def roll_over(self):
		print(f"{self.name} rolled over.")


#根据类创建实例
my_dog = Dog('Willie', 6)

#访问属性
print(f"My dog's name is {my_dog.name}")

#调用方法
my_dog.sit()

使用类和实例

class Car(object):
	"""docstring for Car"""
	def __init__(self, make, model, year):
		self.make = make
		self.model = model
		self.year = year
		#给属性指定默认值
		self.odometer_reading = 0

	def get_descriptive_name(self):
		long_name = f"{self.year} {self.make} {self.model}"
		return long_name.title()

	def read_odometer(self):
		print(f"This car has {self.odometer_reading} miles on it.")

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

my_car = Car('audi', 'a4', 2019)
print(my_car.get_descriptive_name())


##直接修改属性值
my_car.odometer_reading = 55
my_car.read_odometer()


##通过方法修改属性的值
my_car.update_odometer(66)
my_car.read_odometer()

继承

class Car(object):
	"""docstring for Car"""
	def __init__(self, make, model, year):
		self.make = make
		self.model = model
		self.year = year
		#给属性指定默认值
		self.odometer_reading = 0

	def get_descriptive_name(self):
		long_name = f"{self.year} {self.make} {self.model}"
		return long_name.title()

	def read_odometer(self):
		print(f"This car has {self.odometer_reading} miles on it.")

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

	def fill_gas_tank(self, volume):
		self.volume = volume


class ElectricCar(Car):
	"""docstring fos ElectricCar"""
	def __init__(self, make, model, year, battery_size=75):
		#初始化父类的属性
		super().__init__(make, model, year)
		#子类定义属性
		self.battery_size = battery_size
	
	#子类定义方法	
	def describe_battery(self):
		print(f"This car has a {self.battery_size}-kWh battery.")

	#覆盖父类方法
	def fill_gas_tank(self, volume):
		print("This car does't need a gas tank.")

my_tesla = ElectricCar('tesla', 'model s', '2019')
print(my_tesla.get_descriptive_name())
my_tesla.describe_battery()
my_tesla.fill_gas_tank(50)

导入类

#导入类
from car import Car, ElectricCar

my_beetle = Car('volkswagen', 'beetle', 2019)
my_tesla = ElectricCar('tesla', 'roadster', 2020)


#导入模块
import car
my_beetle = car.Car('volkswagen', 'beetle', 2019)