如何根据if语句的条件提出特定的例外？

Question

我有多个例外，只有在条件为真时才想提出特定的异常。你知道是否可能吗？

def lambda_handler(event, context):

    verif = boto3.resource('iam')
    client_iam = boto3.client('iam')
    user = verif.User('Tom')
    try:
        user.load()
        if verif.exceptions.NoSuchEntityException:
            raise Userdoesnotexist
        if ex.response['Error']['Code'] != 'NoSuchEntityException':
            raise Userexists

    except Userdoesnotexist:

    except Userexists:

Answer 1

是的。应该有可能。例如，我从Python的错误和例外文档中找到了这一点。

在此示例中，例外已放在列表中。 并且例外是一个一个

class B(Exception):
    pass

class C(B):
    pass

class D(C):
    pass

for cls in [B, C, D]:
    try:
        raise cls()
    except D:
        print("D")
    except C:
        print("C")
    except B:
        print("B")

该列表已在for循环中迭代，

class Userdoesnotexist(Exception):
    def __init__(self, message):            
        # Call the base class constructor with the parameters it needs
        super().__init__(message)

class Userexists(Exception):
    def __init__(self, message):            
        # Call the base class constructor with the parameters it needs
        super().__init__(message)

def lambda_handler(event, context):

    verif = boto3.resource('iam')
    client_iam = boto3.client('iam')
    user = verif.User('Tom')
    try:
        user.load()
        if verif.exceptions.NoSuchEntityException:
            raise Userdoesnotexist("user does not exist.")
        if ex.response['Error']['Code'] != 'NoSuchEntityException':
            raise Userexists("user exist.")

。 stackoverflow.com/questions/1319615/proper-way-to-declare-custom-exceptions-in-Modern-python"> thread 。