#16211: using negated F()-expression in update query
-------------------------------------+-------------------------------------
Reporter: wdoekes | Owner: nobody
Type: New feature | Status: reopened
Component: Database layer | Version: master
(models, ORM) | Resolution:
Severity: Release blocker | Triage Stage: Ready for
Keywords: | checkin
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by akaariai):
The problem is that in 1.4 we already do define '&' and '|' to behave as
bitwise operators. This is not documented, but the behaviour is there and
tested. For this feature we need the same '&' and '|' operators to do
boolean AND and OR operations in the DB. This is a conflict which I don't
see any nice way to resolve. The best would be to have f1.bitand(f2) and
f1.bitor(f2). But, if we do this we will be silently breaking existing
code using the '&' and '|' operators.
As for `__hash__` - from Python 3 docs:
{{{
Called by built-in function hash() and for operations on members of hashed
collections
including set, frozenset, and dict. __hash__() should return an integer.
The only
required property is that objects which compare equal have the same hash
value...
}}}
The problem is all F-objects compare equal to each other by the `__eq__`
override, and for that reason we can't implement `__hash__`.
--
Ticket URL: <https://code.djangoproject.com/ticket/16211#comment:25>
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