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Refs #30278 -- Doc'd behavior of del on an unaccessed cached_property. 

Thanks to Curtis Maloney for the description of the problem.
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Matthew Schinckel 2019-03-30 23:59:03 +10:30 committed by Tim Graham
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docs/ref/utils.txt
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@ -473,6 +473,10 @@ https://web.archive.org/web/20110718035220/http://diveintomark.org/archives/2004
# set a value manually, that will persist on the instance until cleared
person.friends = ["Huckleberry Finn", "Tom Sawyer"]
Because of the way the `descriptor protocol
<descriptor-invocation>`_ works, using ``del`` (or ``delattr``) on a
``cached_property`` that hasn't been accessed raises ``AttributeError``.
As well as offering potential performance advantages, ``@cached_property``
can ensure that an attribute's value does not change unexpectedly over the
life of an instance. This could occur with a method whose computation is