Python，区分自定义异常

Question

这里是 Python 的新手。有这个代码:

def someFunction( num ):
    if num < 0:
        raise Exception("Negative Number!")
    elif num > 1000:
        raise Exception("Big Number!")
    else:
        print "Tests passed"


try:
    someFunction(10000)
except Exception:
    print "This was a negative number but we didn't crash"
except Exception:
    print "This was a big number but we didn't crash"
else:
    print "All tests passed and we didn't crash"

我最初使用 raise "Negative Number!" 等，但很快发现这是旧的处理方式，您必须调用 Exception 类。现在它工作正常，但我如何区分我的两个异常？对于下面的代码，它正在打印“这是一个负数，但我们没有崩溃”。对此的任何指示都会很棒。谢谢!

Answer 1

如果您希望能够区分发生的异常类型，则需要创建自己的异常类。示例(我继承自 ValueError，因为我认为这是最接近您想要的 - 如果区别无关紧要，它还允许您只捕获 ValueError):

class NegativeError(ValueError):
    pass

class BigNumberError(ValueError):
    pass

def someFunction( num ):
    if num < 0:
        raise NegativeError("Negative Number!")
    elif num > 1000:
        raise BigNumberError("Big Number!")
    else:
        print "Tests passed"

try:
    someFunction(10000)
except NegativeError as e:
    print "This was a negative number but we didn't crash"
    print e
except BigNumberError as e:
    print "This was a big number but we didn't crash"
    print e
else:
    print "All tests passed and we didn't crash"