异常

语法

try:
    # do something
except ExceptionName:
    # do something
finally:
    # do something

自定义异常

class MyError(Exception):
    def __init__(self, value):
        self.value = value
    def __str__(self):
        return repr(self.value)

抛出异常

try:
    raise MyError('something')
except MyError as e:
    print('Error value: ' + e.value)