关于 python 几个常用和比较基础的高级用法

一： 通过代码连续运行命令行命令：

import os 

os.system('cd && ls && cd work')

二： 类属性

from datetime import date, datetime
class User:
    def __init__(self, name, birthday):
        self.name = name
        self.birthday = birthday
        self._age = 0

    # def get_age(self):
    #     return datetime.now().year - self.birthday.year

    @property
    def age(self):
        return datetime.now().year - self.birthday.year

    @age.setter
    def age(self, value):
        self._age = value

if __name__ == "__main__":
    user = User("bobby", date(year=1987, month=1, day=1))
    user.age = 30
    print (user._age)
    print(user.age)

三：yield 的使用方式

def fab(max):
    n, a, b = 0, 0, 1
    while n < max:
        yield b
        a, b = b, a + b
        n += 1
    return "done"


if __name__ == "__main__":
    # read_file("C:/Users/ThinkPad/Desktop/log.txt")
    a = fab(5)
    print(a.__next__())
    print(a.__next__())
    print(a.__next__())
    print(a.__next__())
    print(a.__next__())
    print(a.__next__())  # 报错StopIteration

四： python 的 new 和 init

class User:
    def __new__(cls, *args, **kwargs):
        print (" in new ")
        return super().__new__(cls)
    def __init__(self, name):
        print (" in init")
        pass

#new 是用来控制对象的生成过程， 在对象生成之前
#init是用来完善对象的
#如果new方法不返回对象， 则不会调用init函数
if __name__ == "__main__":
    user = User(name="bobby")