学习python第九天-优快云博客

今天学习了new方法，new方法的单例模式，异常，异常的捕获，制造异常，相关笔记如下

#new方法
class CapStr(str):
    def __new__(cls, *args, **kwargs):
        return super().__new__(cls)


    def __init__(self,string):

        self.string=string.upper()


a=CapStr("i love you")
print(a.string)

#print("i love you".upper())

#单例模式

class Person:
    pass

xiaoming= Person()

xiaohong= Person()

# print(id(xiaohong))
# print(id(xiaoming))

class A:
    _instance=None #实例 私有属性
    def __new__(cls, *args, **kwargs):
        if cls._instance==None:
            cls._instance=object.__new__(cls)#super和object都可以
            return cls._instance
        else:
            return cls._instance

a=A()
b=A()

print(id(a))
print(id(a))

#BaseException

SystemExit #python退出异常
KeyboardInterrupt #ctrl+c
GeneratorExit #
Exception #普通异常

#以上都继承BaseException

#错误回溯，也叫异常传递
# def a():
#     aaa
#
# def b():
#     a()
#
# def c():
#     b()
#
# c()

# try:
#     a
# except Exception as e:
#     print(e)

#制作异常
class jianqiError(Exception):
    pass

def func(name):
    if name == "哈哈哈":
        print("非常好")
    else:
        raise jianqiError("不行")

try:
    func("haha")
except jianqiError as e:
    print(e)