Question

我正在创建一个名为Conversation的类作为更大代码的一部分，并希望确保用户输入的字段是有效的（如果它们无效则我想提出值错误），但是当我运行程序时，我的is_valid方法不起作用：

课堂对话：

def __init__(self, members, size_limit, backup_policy, cloud_account_prefix='./'):
    if not self.is_valid():
        raise ValueError
    self.members = members
    self.size_limit = size_limit
    self.backup_policy = backup_policy
    self.cloud_account_prefix = cloud_account_prefix
    self.backup_count = 0
    self.size_count = 0
    self.messages = []

def is_valid(self, members, size_limit, backup_policy, cloud_account_prefix):
    if self.members < 2:
        return False
    if self.size_limit <= 10:
        return False
    if not path_ok(self.cloud_account_prefix):
        return False
    if self.backup_policy < 1:
        return False
    else:
        return True

我做错了什么？

Answer 1

在进行任何初始化之前，您正在调用is_valid，因此对self.something内的AttribueError进行任何调用都会产生is_valid。
class Conversation: def __init__(self, members, size_limit, backup_policy, cloud_account_prefix='./'): self.members = members self.size_limit = size_limit self.backup_policy = backup_policy self.cloud_account_prefix = cloud_account_prefix self.backup_count = 0 self.size_count = 0 self.messages = [] if not self.is_valid(): raise ValueError def is_valid(self): if self.members < 2: return False if self.size_limit <= 10: return False if not path_ok(self.cloud_account_prefix): return False if self.backup_policy < 1: return False else: return True需要4个参数，你用0来称呼它。

您的代码应为

__init__

另一种方法可能是将所有参数从is_valid传递给class Conversation: def __init__(self, members, size_limit, backup_policy, cloud_account_prefix='./'): if not self.is_valid(members, size_limit, backup_policy, cloud_account_prefix): raise ValueError self.members = members self.size_limit = size_limit self.backup_policy = backup_policy self.cloud_account_prefix = cloud_account_prefix self.backup_count = 0 self.size_count = 0 self.messages = [] def is_valid(self, members, size_limit, backup_policy, cloud_account_prefix): if members < 2: return False if size_limit <= 10: return False if not path_ok(cloud_account_prefix): return False if backup_policy < 1: return False else: return True，以便在开始初始化实例属性之前验证它们是否有效：

//Element[@attribute1="abc" and @attribute2="xyz" and .="Data"]

验证类中的方法

1 个答案: