make types compatible with older Python versions

[nominatim.git] / nominatim / typing.py

diff --git a/nominatim/typing.py b/nominatim/typing.py
index 36bde8347e7dd4fc8d94e9b9ea422f5ec1a77810..ebb5e1e9d56f05fe91e52dda6c73d59365afee81 100644 (file)
--- a/nominatim/typing.py
+++ b/nominatim/typing.py
@@ -2,7 +2,7 @@
 #
 # This file is part of Nominatim. (https://nominatim.org)
 #
 #
 # This file is part of Nominatim. (https://nominatim.org)
 #

-# Copyright (C) 2022 by the Nominatim developer community.
+# Copyright (C) 2023 by the Nominatim developer community.

 # For a full list of authors see the git log.
 """
 Type definitions for typing annotations.
 # For a full list of authors see the git log.
 """
 Type definitions for typing annotations.


@@ -11,8 +11,9 @@ Complex type definitions are moved here, to keep the source files readable.
 """
 from typing import Any, Union, Mapping, TypeVar, Sequence, TYPE_CHECKING
 
 """
 from typing import Any, Union, Mapping, TypeVar, Sequence, TYPE_CHECKING
 

-# Generics varaible names do not confirm to naming styles, ignore globally here.
-# pylint: disable=invalid-name,abstract-method,multiple-statements,missing-class-docstring
+# Generics variable names do not confirm to naming styles, ignore globally here.
+# pylint: disable=invalid-name,abstract-method,multiple-statements
+# pylint: disable=missing-class-docstring,useless-import-alias

 
 if TYPE_CHECKING:
     import psycopg2.sql
 
 if TYPE_CHECKING:
     import psycopg2.sql


@@ -36,3 +37,37 @@ class DictCursorResult(Mapping[str, Any]):
 DictCursorResults = Sequence[DictCursorResult]
 
 T_cursor = TypeVar('T_cursor', bound='psycopg2.extensions.cursor')
 DictCursorResults = Sequence[DictCursorResult]
 
 T_cursor = TypeVar('T_cursor', bound='psycopg2.extensions.cursor')

+
+# The following typing features require typing_extensions to work
+# on all supported Python versions.
+# Only require this for type checking but not for normal operations.
+
+if TYPE_CHECKING:
+    from typing_extensions import (Protocol as Protocol,
+                                   Final as Final,
+                                   TypedDict as TypedDict)
+else:
+    Protocol = object
+    Final = 'Final'
+    TypedDict = dict
+
+
+# SQLAlchemy introduced generic types in version 2.0 making typing
+# incompatible with older versions. Add wrappers here so we don't have
+# to litter the code with bare-string types.
+
+if TYPE_CHECKING:
+    import sqlalchemy as sa
+    from typing_extensions import (TypeAlias as TypeAlias)
+else:
+    TypeAlias = str
+
+SaSelect: TypeAlias = 'sa.Select[Any]'
+SaScalarSelect: TypeAlias = 'sa.ScalarSelect[Any]'
+SaRow: TypeAlias = 'sa.Row[Any]'
+SaColumn: TypeAlias = 'sa.ColumnElement[Any]'
+SaExpression: TypeAlias = 'sa.ColumnElement[bool]'
+SaLabel: TypeAlias = 'sa.Label[Any]'
+SaFromClause: TypeAlias = 'sa.FromClause'
+SaSelectable: TypeAlias = 'sa.Selectable'
+SaBind: TypeAlias = 'sa.BindParameter[Any]'