Question

例如：

try:
    myfruits = FruitFunction()    #Raises some exception (unknown)
    assert "orange" in myfruits   #Raises AssertionError (known)

except:
    # I don't know how to distinguish these two errors :(

我需要从其他所有未知的异常中过滤出一种特殊的异常（已知）。我还需要断言来继续相同的异常处理，

try:
    myfruits = FruitFunction()    #Raises some exception (unknown)
    assert "orange" in myfruits   #Raises AssertionError (known)

except AssertionError:
    # Handle Assertion Errors here
    # But I want the except below to happen too!

except:
    # Handle everything here

我将添加一个真实的例子来更简洁地传达这个想法：

try:
    # This causes all sorts of errors
    myurl = urllib.urlopen(parametes)

    # But if everything went well
    assert myurl.status == 202

    # proceed normal stuff

except:
    # print "An error occured" if any error occured
    # but if it was an assertion error,
    # add "it was something serious too!"

Answer 1

try:
    try:
        myfruits = FruitFunction()    #Raises some exception (unknown)
        assert "orange" in myfruits   #Raises AssertionError (known)
    except AssertionError:
        # handle assertion
        raise
except Exception:
    # handle everything

我假设你不能将抛出不同异常的两个语句分开（例如，因为它们在另一个函数中一起关闭）。如果可以的话，以下内容更加精确和直接：

try:
    myfruits = FruitFunction()    #Raises some exception (unknown)
    try:
        assert "orange" in myfruits   #Raises AssertionError (known)
    except AssertionError:
        # handle assertion
        raise
except Exception:
    # handle everything

它更精确，因为如果FruitFunction()引发的未知异常恰好是AssertionError，那么它就不会被内部try捕获。在不分离语句的情况下，没有（合理的）方法来区分从两个不同位置抛出的两个相同类型的异常。因此，对于第一个代码，您最好希望FruitFunction()不会引发AssertionError，或者如果它发生，那么它可以像处理另一个代码一样处理。

Answer 2

try:
    # Do something
    myurl = urllib.urlopen(parametes)
    assert myurl.status == 202
except Exception as e:
    # Handle Exception
    print('An error occured')
    if isinstance(e, AssertionError):
        # Handle AssertionError
        print('it was something serious too!')
else:
    # proceed normal stuff

Answer 3

如果它既引发了一个未知异常又引发了AssertionError，并且您需要同时处理它们，则应该使用两个单独的try语句。

try:
    raise IndexError()
    assert 'orange' in myfruits
except AssertionError:
    print 'AssertionError'
except:
    print 'another error'

以上只会捕捉第一个错误，而

try:
    raise IndexError()
except:
    print 'another error'
try:
    assert 'orange' in myfruits
except AssertionError:
    print 'AssertionError'

将捕获这两个错误。

如何区分同一个try语句中出现的不同异常

3 个答案: