pep-484: sqlalchemy.sql pass one

sqlalchemy.sql will require many passes to get all
modules even gradually typed.  Will have to pick and
choose what modules can be strictly typed vs. which
can be gradual.

in this patch, emphasis is on visitors.py, cache_key.py,
annotations.py for strict typing, compiler.py is on gradual
typing but has much more structure, in particular where it
connects with the outside world.

The work within compiler.py also reached back out to
engine/cursor.py , default.py quite a bit.

References: #6810
Change-Id: I6e8a29f6013fd216e43d45091bc193f8be0368fd

1 files changed, 19 insertions, 10 deletions

diff --git a/lib/sqlalchemy/sql/selectable.py b/lib/sqlalchemy/sql/selectable.py
index e5c2bef68..09befb078 100644
--- a/lib/sqlalchemy/sql/selectable.py
+++ b/lib/sqlalchemy/sql/selectable.py
@@ -53,7 +53,6 @@ from .base import Generative
 from .base import HasCompileState
 from .base import HasMemoized
 from .base import Immutable
-from .base import prefix_anon_map
 from .coercions import _document_text_coercion
 from .elements import _anonymous_label
 from .elements import BindParameter
@@ -69,10 +68,10 @@ from .elements import literal_column
 from .elements import TableValuedColumn
 from .elements import UnaryExpression
 from .visitors import InternalTraversal
+from .visitors import prefix_anon_map
 from .. import exc
 from .. import util
 
-
 and_ = BooleanClauseList.and_
 
 _T = TypeVar("_T", bound=Any)
@@ -855,6 +854,12 @@ class FromClause(roles.AnonymizedFromClauseRole, Selectable):
         return self.alias(name=name)
 
 
+class NamedFromClause(FromClause):
+    named_with_column = True
+
+    name: str
+
+
 class SelectLabelStyle(Enum):
     """Label style constants that may be passed to
     :meth:`_sql.Select.set_label_style`."""
@@ -1317,15 +1322,16 @@ class NoInit:
 #        -> Lateral -> FromClause, but we accept SelectBase
 #           w/ non-deprecated coercion
 #        -> TableSample -> only for FromClause
-class AliasedReturnsRows(NoInit, FromClause):
+class AliasedReturnsRows(NoInit, NamedFromClause):
     """Base class of aliases against tables, subqueries, and other
     selectables."""
 
     _is_from_container = True
-    named_with_column = True
 
     _supports_derived_columns = False
 
+    element: ClauseElement
+
     _traverse_internals = [
         ("element", InternalTraversal.dp_clauseelement),
         ("name", InternalTraversal.dp_anon_name),
@@ -1423,6 +1429,8 @@ class Alias(roles.DMLTableRole, AliasedReturnsRows):
 
     inherit_cache = True
 
+    element: FromClause
+
     @classmethod
     def _factory(cls, selectable, name=None, flat=False):
         return coercions.expect(
@@ -1689,6 +1697,8 @@ class CTE(
         + HasSuffixes._has_suffixes_traverse_internals
     )
 
+    element: HasCTE
+
     @classmethod
     def _factory(cls, selectable, name=None, recursive=False):
         r"""Return a new :class:`_expression.CTE`,
@@ -1819,7 +1829,7 @@ class _CTEOpts(NamedTuple):
     nesting: bool
 
 
-class HasCTE(roles.HasCTERole):
+class HasCTE(roles.HasCTERole, ClauseElement):
     """Mixin that declares a class to include CTE support.
 
     .. versionadded:: 1.1
@@ -2247,6 +2257,8 @@ class Subquery(AliasedReturnsRows):
 
     inherit_cache = True
 
+    element: Select
+
     @classmethod
     def _factory(cls, selectable, name=None):
         """Return a :class:`.Subquery` object."""
@@ -2331,7 +2343,7 @@ class FromGrouping(GroupedElement, FromClause):
         self.element = state["element"]
 
 
-class TableClause(roles.DMLTableRole, Immutable, FromClause):
+class TableClause(roles.DMLTableRole, Immutable, NamedFromClause):
     """Represents a minimal "table" construct.
 
     This is a lightweight table object that has only a name, a
@@ -2371,8 +2383,6 @@ class TableClause(roles.DMLTableRole, Immutable, FromClause):
         ("name", InternalTraversal.dp_string),
     ]
 
-    named_with_column = True
-
     _is_table = True
 
     implicit_returning = False
@@ -2542,7 +2552,7 @@ class ForUpdateArg(ClauseElement):
 SelfValues = typing.TypeVar("SelfValues", bound="Values")
 
 
-class Values(Generative, FromClause):
+class Values(Generative, NamedFromClause):
     """Represent a ``VALUES`` construct that can be used as a FROM element
     in a statement.
 
@@ -2553,7 +2563,6 @@ class Values(Generative, FromClause):
 
     """
 
-    named_with_column = True
     __visit_name__ = "values"
 
     _data = ()