1 raise BaseException

 1 try:
 2     1/0
 3     print(a)
 4 except ZeroDivisionError as e:  # as后是前的标识符
 5     print(type(e), e)
 6 except NameError as e:
 7     print(type(e), e)
 8 else:
 9     print(‘OK‘)  # 没有捕获错误时执行
10 finally:
11     print(‘finally‘)  # finally必定执行
12 # <class ‘ZeroDivisionError‘> division by zero
13 # finally

 1 try:
 2     print(a)
 3     1/0
 4 except ZeroDivisionError as e:  # as后是前的标识符
 5     print(type(e), e)
 6 except NameError as e:
 7     print(type(e), e)
 8 else:
 9     print(‘OK‘)  # 没有捕获错误时执行
10 finally:
11     print(‘finally‘)  # finally必定执行
12 # <class ‘NameError‘> name ‘a‘ is not defined
13 # finally

 1 a = 1
 2 try:
 3     print(a)
 4 except ZeroDivisionError as e:  # as后是前的标识符
 5     print(type(e), e)
 6 except NameError as e:
 7     print(type(e), e)
 8 else:
 9     print(‘OK‘)  # 没有捕获错误时执行
10 finally:
11     print(‘finally‘)  # finally必定执行
12 # 1
13 # OK
14 # finally

 1 import argparse
 2 parser = argparse.ArgumentParser(prog=‘ls‘, add_help=True, description=‘list directory contents‘)  # add_help开启-p,--help命令
 3 parser.add_argument(‘path‘, nargs=‘?‘, default=‘.‘, help=‘directory‘)  # path缺省为当前目录‘.‘，可以在命令行界面自定义目录
 4 parser.add_argument(‘-a‘, ‘--all‘, action=‘store_true‘, help=‘show all files, do not ignore entries starting with .‘)
 5 parser.add_argument(‘-l‘, action=‘store_true‘, help=‘use a long listing format‘)
 6 args = parser.parse_args()  # Namespace(all=False, l=False, path=‘.‘)
 7 parser.print_help()
 8 # usage: ls [-h] [-a] [-l] [path]
 9 # 
10 # list directory contents
11 # 
12 # positional arguments:
13 #   path        directory
14 # 
15 # optional arguments:
16 #   -h, --help  show this help message and exit
17 #   -a, --all   show all files, do not ignore entries starting with .
18 #   -l          use a long listing format