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    <p>One solution would be to wrap the outer object inside a Proxy that handles None values for you. See below for a beginning implementation.</p> <p>import unittest</p> <pre><code>class SafeProxy(object): def __init__(self, instance): self.__dict__["instance"] = instance def __eq__(self, other): return self.instance==other def __call__(self, *args, **kwargs): return self.instance(*args, **kwargs) # TODO: Implement other special members def __getattr__(self, name): if hasattr(self.__dict__["instance"], name): return SafeProxy(getattr(self.instance, name)) if name=="val": return lambda: self.instance return SafeProxy(None) def __setattr__(self, name, value): setattr(self.instance, name, value) # Simple stub for creating objects for testing class Dynamic(object): def __init__(self, **kwargs): for name, value in kwargs.iteritems(): self.__setattr__(name, value) def __setattr__(self, name, value): self.__dict__[name] = value class Test(unittest.TestCase): def test_nestedObject(self): inner = Dynamic(value="value") middle = Dynamic(child=inner) outer = Dynamic(child=middle) wrapper = SafeProxy(outer) self.assertEqual("value", wrapper.child.child.value) self.assertEqual(None, wrapper.child.child.child.value) def test_NoneObject(self): self.assertEqual(None, SafeProxy(None)) def test_stringOperations(self): s = SafeProxy("string") self.assertEqual("String", s.title()) self.assertEqual(type(""), type(s.val())) self.assertEqual() if __name__=="__main__": unittest.main() </code></pre> <p>NOTE: I am personally not sure wether I would use this in an actual project, but it makes an interesting experiment and I put it here to get people thoughts on this.</p>
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    1. POHow to chain attribute lookups that might return None in Python?
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    1. COThis is a clever solution, and probably what I had in mind when I asked the question. This solution ends up being pretty heavyweight, and also has the disadvantage that all the attribute accesses are done even when one of the intermediate ones returns None and could potentially short-circuit the expression evaluation.
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      1. USDavid Hull
 

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