whenever you say somecol.label(), now counts itself
in its "proxy_set" unioned with that of it's
contained column's proxy set, instead of
directly returning that of the contained column.
This allows column correspondence
operations which depend on the identity of the
_Labels themselves to return the correct result
- fixes ORM bug [ticket:1852].
a custom Column subclass can safely override
_constructor to return Column, for the purposes of
making "configurational" column classes that aren't
involved in proxying, etc.
if the left side is a join, it will attempt to join the right
side to the rightmost side of the left first, and not raise
any exceptions about ambiguous join conditions if successful
even if there are further join targets across the rest of
the left. [ticket:1714]
correspondence for cloned selectables which contain
free-standing column expressions. This bug is
generally only noticeable when exercising newer
ORM behavior only availble in 0.6 via [ticket:1568],
but is more correct at the SQL expression level
as well. [ticket:1617]
Mike Bayer