Pythonic 处理此错误情况
在下面的代码中，我使用 assert 是否合理？如果出现任何问题，当我尝试访问属性时无论如何都会发生错误。另一方面，断言提供了描述性错误消息。
你认为我应该保留这个断言吗？
class WeakBoundMethod:
def __init__(self, meth):
assert (hasattr(meth, '__func__') and hasattr(meth, '__self__')),\
'Object is not a bound method.'
self._self = weakref.ref(meth.__self__)
self._func = meth.__func__
In the code below, is my use of assert justified? If anything is wrong, an error will occur anyway when I try to access the attributes. On the other hand, the assert provides a descriptive error message.
Do you think I should keep the assertion?
class WeakBoundMethod:
def __init__(self, meth):
assert (hasattr(meth, '__func__') and hasattr(meth, '__self__')),\
'Object is not a bound method.'
self._self = weakref.ref(meth.__self__)
self._func = meth.__func__
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assert不是用于输入验证，而是用于查找您构建代码所依据的假设中的缺陷。它是一个调试和文档工具，但可以禁用。如果你想提供一个好的错误消息，raise TypeError("Object is not abound method")- 这就是它的用途。assertis not for input validation, it's for finding flaws in the assumptions you built your code on. It's a debugging and documentation tool, but it can be disabled. If you want to provide a good error message,raise TypeError("Object is not a bound method")- that's what it's for.在我看来，这里的
assert正在检查代码所做的假设。如果类使用不正确（即编程错误），它将失败。如果情况确实如此，那么恕我直言，这里使用
assert是合理的。确实，当使用不正确时，Python 会慷慨地抛出异常，而 EAFP 是一个很好的策略。然而，有时解释器抛出的错误描述性不够，无法轻松定位问题，在这种情况下使用assert是合适的。它还应该与适当的文档相结合，说明类期望如何使用（即传递的方法应该具有某些属性）。如果我误解了您的示例，并且您在此处使用
assert来验证用户可能犯的错误，那么这不是一个好主意。It appears to me that the
asserthere is checking an assumption the code is making. It will fail if the class is used incorrectly (i.e. programming error).If this is indeed the case, then the use of
asserthere is IMHO justified. True, Python generously throws exceptions when things are used incorrectly, and EAFP is a good strategy. Yet, sometimes the errors thrown by the interpreter aren't descriptive enough to make it easy to locate the problem, and anassertin such cases is appropriate. It should also be coupled with appropriate documentation that states how the class expects to be used (i.e. the passed method should have certain attributes).If I have misunderstood your sample and you're using the
asserthere to validate something the user could err with, then it's not a good idea.