Question

class My_custom_exception(Exception):
    def __init__(self, ErrNum, *arg, **kwargs):
        self.ErrNum = int(ErrNum)
        self.ErrMsg = ""  # Set appropriate message depending an error number

        if self.ErrNum  & 0x00000000 !=0:
            self.ErrMsg = "NO ERROR"
        if self.ErrNum   & 0x00000001 !=0:
            self.ErrMsg  = "Error 1 occured"
        if self.ErrNum   & 0x00000002 !=0:
            self.ErrMsg  = "Error 2 occured"
        if self.ErrNum   & 0x00000004 !=0:
            self.ErrMsg  = "Error 3 occured"
        if self.ErrNum   & 0x00000008 !=0:
            self.ErrMsg  = "Error 4 occured"

   def __str__(self):
        return "ERROR (0x%08X): %s" % (self.ErrNum, self.ErrMsg )

    def __repr__(self):
        return self.__str__()


def check_error(error_nr):
    if error_nr > 0:
        raise My_custom_exception(error_nr)

try:
    check_error(3)
except My_custom_exception as e:
    print e

输出：

My_custom_exception (0x00000003): Error 2 occurred.

我的目标是同时打印Error 1 occurred和Error 2 occurred。

如果我给check_error(5)然后Error 4 occurred，我还想避免这种情况，这是另一个问题。

Answer 1

我会这样做：

class MyCustomException(Exception):  # note naming convention

    MESSAGES = {
        0x00000000: 'NO ERROR',
        0x00000001: 'Error 1 occurred',
        0x00000002: 'Error 2 occurred',
        0x00000004: 'Error 3 occurred',
        ...
    }

    def __init__(self, err_num, *args, **kwargs):
        super(MyCustomException, self).__init__(*args, **kwargs)  # handle inheritance
        self.err_num = int(err_num)
        self.err_msg = self._create_err_msg(self.err_num)

    def __str__(self):
        return "ERROR (0x%08X): %s" % (self.err_num, self.err_msg)

    def __repr__(self):
        # Note that __repr__ should be eval-able
        return 'MyCustomException(%d)' % self.err_num

    @classmethod
    def _create_err_msg(cls, err_num):
        messages = []
        for num, msg in cls.MESSAGES.items():
            if err_num & num:
                messages.append(msg)
        return ' and '.join(messages) if messages else cls.MESSAGES[0]

请注意，这通过将错误消息提取到字典类属性中来简化代码;使它成为一个单独的方法也使得更容易单独测试：

>>> MyCustomException._create_err_msg(5)
'Error 1 occurred and Error 3 occurred'
>>> MyCustomException._create_err_msg(2)
'Error 2 occurred'
>>> MyCustomException._create_err_msg(0)
'NO ERROR'

使用中：

>>> exc = MyCustomException(5)
>>> str(exc)
'ERROR (0x00000005): Error 1 occurred and Error 3 occurred'

Answer 2

这可能有效：收集列表中的错误（格式化可能需要一些工作，但这应该是一个开始）：

class My_custom_exception(Exception):
    def __init__(self, ErrNum, *arg, **kwargs):
        self.ErrNum = int(ErrNum)
        self.ErrMsgs = []

        if self.ErrNum  & 0x00000000 !=0:
            self.ErrMsgs = ["NO ERROR"]
        if self.ErrNum   & 0x00000001 !=0:
            self.ErrMsgs.append("Error 1 occured (0x00000001)")
        if self.ErrNum   & 0x00000002 !=0:
            self.ErrMsgs.append("Error 2 occured (0x00000002)")
        if self.ErrNum   & 0x00000004 !=0:
            self.ErrMsgs.append("Error 3 occured (0x00000004)")
        if self.ErrNum   & 0x00000008 !=0:
            self.ErrMsgs.append("Error 4 occured (0x00000008)")

    def __str__(self):
        return "ERRORS: %s" % ', '.join(self.ErrMsgs)

示例的输出：

ERRORS: Error 1 occured (0x00000001), Error 2 occured (0x00000002)

自定义异常处理显示错误消息和错误号

2 个答案: