缺失值的元组

问题描述

我在 python 中有一个函数可以对字符串进行错误检查.如果函数发现错误，它将返回一个带有错误代码和该错误标识符的元组.稍后在程序中我有处理错误的函数.它将元组接受为两个变量.

I have a function in python that does error checking on a string. If the function finds an error it will return a tuple with an error code and an identifier for that error. Later in the program I have the function that handles the error. It accepts the tuple into two variables.

errCode, i = check_string(s,pathType)

check_string 是产生元组的函数.如果没有错误，我希望它做的是返回零.当返回零时，上面的代码似乎失败了，因为变量 i 没有任何内容.

check_string is the function that produces the tuple. What I want it to does is return just zero if there is no error. When a zero is returned the above code seems to fail because there is nothing for the variable i.

是否有一种简单的方法可以让它工作，或者如果没有发现错误，我是否只需要让程序返回一个 0 和 0 的元组?

Is there an easy way to get this to work or do I just need to have the program return a tuple of 0 and 0 if no error is found?

推荐答案

我会为此使用异常系统.

I would use the exception system for this.

class StringError(Exception):
    NO_E = 0
    HAS_Z = 1

def string_checker(string):
    if 'e' not in string:
        raise StringError('e not found in string', StringError.NO_E)
    if 'z' in string:
        raise StringError('z not allowed in string', StringError.HAS_Z)
    return string.upper()

s = 'testing'
try:
    ret = string_checker(s)
    print 'String was okay:', ret
except StringError as e:
    print 'String not okay with an error code of', e.args[1]

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