封装、继承、多态
class Book: def __init__(self,title,price=0.0,author=None): self.title = title self.price = price self.author = author def print_info(self): print(self.title,self.price,self.author) if __name__ == "__main__": book = Book("python经典",price=39.0,author="tom") book.print_info()结果是： python经典 39.0 tom
class Book: def __init__(self,title,price=0.0,author=None): self.title = title self.price = price self.author = author def print_info(self): print(self.title,self.price,self.author) def __repr__(self): return"<图书:{}>".format(self.title) class Book: count = 0 #初始化执行 def __init__(self,title,price=0.0,author=None): self.title = title self.price = price self.author = author Book.count +=1 def __del__(self): Book.count -=1 def print_info(self): print(self.title,self.price,self.author) def __repr__(self): return"<图书:{}>".format(self.title) if __name__ == "__main__": book = Book("python经典","price=29.0",author="tom") book2 = Book("Flask") book3 = Book("财管") del(book3) print("图书数量:{}".format(Book.count))结果是： 图书数量:2 根据年份计算年龄
import datetime class Student: def __init__(self,name,birthdate): self.name = name self.birthdate = birthdate def get_age(self): return datetime.date.today().year - self.birthdate.year if __name__ == "__main__": s = Student("TOM",datetime.date(1992,4,1)) print(s.birthdate) print(s.get_age())结果是： 1992-04-01 27 设置禁止删除
import datetime class Student: def __init__(self,name,birthdate): self.name = name self.birthdate = birthdate @property def age(self): return datetime.date.today().year - self.birthdate.year @age.setter def age(self,value): raise AttributeError("禁止赋值年龄") @age.deleter def age(self): raise AttributeError("年龄不能删除") if __name__ == "__main__": s = Student("TOM",datetime.date(1992,4,1)) print(s.birthdate) print(s.age) s.birthdate = datetime.date(1987,6,13) del(s.age) print(s.age)结果是： Traceback (most recent call last): File “D:/PY/PY1/.idea/test2.py”, line 41, in del(s.age) 1992-04-01 File “D:/PY/PY1/.idea/test2.py”, line 33, in age raise AttributeError(“年龄不能删除”) AttributeError: 年龄不能删除 27
