René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Side effect of FrozenJSON.__getattr__ not raising KeyError","articleBody":"Hi Luciano, \r\n\r\nIn chapter 22 you mention that `FrozenJSON.__getattr__()` raising a `KeyError` is \"not to confusing\". However, today I discovered a side effect from this that __is__ confusing: `copy.copy(FrozenJSON({'name': 'Jim Bo', 'class': 1982}))` raises a `RecursionError`.\r\n\r\nIndeed the documentation states that an `AttributeError` should be raised (https://docs.python.org/3/reference/datamodel.html#object.__getattr__) and apparently this is relied upon in the stdlib. In the copy implementation a new instance of `FrozenJSON` is generated without the initializer being called. Then, when looking for some optional dunder methods (that are not found) the copy implementation triggers a `__getattr__` call with `self.__data` not yet existing, triggering the recursion.\r\n\r\nWhat I appreciate in your book is that you are always very precise about all types of unexpected side effects, so maybe you could consider spending some text on this in a future update. \r\n\r\nBest regards, Michiel","author":{"url":"https://github.com/hayemj","@type":"Person","name":"hayemj"},"datePublished":"2024-07-17T20:12:49.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/46/example-code-2e/issues/46"}