Tim Peters wrote at 2005-7-7 15:03 -0400:
>> However, there is an additional reason not to put "None" into a BTree.
>> Its interface has a weekness in its "keys", "values", "min" and "max"
>> E.g. in "keys(min,max)", "min=None" or "max=None" mean: no restriction.
>> Therefore, they cannot distinguish between a "None" stored in the
>> BTree itself and the use of "None" as "no restriction".
>Yup, except I wouldn't call it a weakness. Since BTrees should not be
>used with mixed key types anyway, and None is only value of type
>type(None), the only BTrees having None as a key should be empty or
>contain a single key (namely, None). Range search on trees with 0 or
>1 elements isn't particularly difficult <wink>.
Restrictions are fine when they are either
* enforced (I know BTrees do not enforce the "no mixed key types"
* clearly documented
I do not know whether the ZODB 3.4 BTrees interfaces document
the restriction (this would be a good place, I think)
Hopefully, they do ;-)
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