establish column_property and query_expression as readonly from a dc perspective

Fixed bug in ORM Declarative Dataclasses where the
:func:`_orm.queryable_attribute` and :func:`_orm.column_property`
constructs, which are documented as read-only constructs in the context of
a Declarative mapping, could not be used with a
:class:`_orm.MappedAsDataclass` class without adding ``init=False``, which
in the case of :func:`_orm.queryable_attribute` was not possible as no
``init`` parameter was included. These constructs have been modified from a
dataclass perspective to be assumed to be "read only", setting
``init=False`` by default and no longer including them in the pep-681
constructor. The dataclass parameters for :func:`_orm.column_property`
``init``, ``default``, ``default_factory``, ``kw_only`` are now deprecated;
these fields don't apply to :func:`_orm.column_property` as used in a
Declarative dataclasses configuration where the construct would be
read-only. Also added read-specific parameter
:paramref:`_orm.queryable_attribute.compare` to
:func:`_orm.queryable_attribute`; :paramref:`_orm.queryable_attribute.repr`
was already present.

Added missing :paramref:`_orm.mapped_column.active_history` parameter
to :func:`_orm.mapped_column` construct.

Fixes: #9628
Change-Id: I2ab44d6b763b20410bd1ebb5ac949a6d223f1ce2

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/sqlalchemy/sql/base.py b/lib/sqlalchemy/sql/base.py
index 1752a4dc1..8186f6ade 100644
--- a/lib/sqlalchemy/sql/base.py
+++ b/lib/sqlalchemy/sql/base.py
@@ -101,6 +101,9 @@ if not TYPE_CHECKING:
 class _NoArg(Enum):
     NO_ARG = 0
 
+    def __repr__(self):
+        return f"_NoArg.{self.name}"
+
 
 NO_ARG = _NoArg.NO_ARG