Refine types and enable typechecking in cursor.py

.pre-commit-config.yaml

@@ -94,6 +94,7 @@ repos:
             (?x)^src/snowflake/connector/(
                 constants
                 | compat
+                | cursor
                 | dbapi
                 | description
                 | errorcode

DESCRIPTION.md

@@ -8,9 +8,11 @@ Source code is also available at: https://github.com/snowflakedb/snowflake-conne
 
 # Release Notes
 
-- v3.12.5(TBD)
+- v3.13.1(January 23,2025)
+  - Updated type hints for cursor object
+
+- v3.13.0(January 23,2025)
   - Added a feature to limit the sizes of IO-bound ThreadPoolExecutors during PUT and GET commands.
-  - Adding support for the new PAT authentication method.
   - Updated README.md to include instructions on how to verify package signatures using `cosign`.
   - Updated the log level for cursor's chunk rowcount from INFO to DEBUG.
   - Added a feature to verify if the connection is still good enough to send queries over.

src/snowflake/connector/connection.py

@@ -25,7 +25,16 @@
 from threading import Lock
 from time import strptime
 from types import TracebackType
-from typing import Any, Callable, Generator, Iterable, Iterator, NamedTuple, Sequence
+from typing import (
+    Any,
+    Callable,
+    Generator,
+    Iterable,
+    Iterator,
+    NamedTuple,
+    Sequence,
+    TypeVar,
+)
 from uuid import UUID
 
 from cryptography.hazmat.backends import default_backend
@@ -115,6 +124,7 @@
 DEFAULT_CLIENT_PREFETCH_THREADS = 4
 MAX_CLIENT_PREFETCH_THREADS = 10
 DEFAULT_BACKOFF_POLICY = exponential_backoff()
+T = TypeVar("T", bound=SnowflakeCursor)
 
 
 def DefaultConverterClass() -> type:
@@ -442,7 +452,7 @@ def __init__(
             elif "streamlit" in sys.modules:
                 kwargs["application"] = "streamlit"
 
-        self.converter = None
+        self.converter: SnowflakeConverter | None = None
         self.query_context_cache: QueryContextCache | None = None
         self.query_context_cache_size = 5
         if connections_file_path is not None:
@@ -868,9 +878,7 @@ def rollback(self) -> None:
         """Rolls back the current transaction."""
         self.cursor().execute("ROLLBACK")
 
-    def cursor(
-        self, cursor_class: type[SnowflakeCursor] = SnowflakeCursor
-    ) -> SnowflakeCursor:
+    def cursor(self, cursor_class: type[T] = SnowflakeCursor) -> T:
         """Creates a cursor object. Each statement will be executed in a new cursor object."""
         logger.debug("cursor")
         if not self.rest:
@@ -938,7 +946,7 @@ def setup_ocsp_privatelink(app, hostname) -> None:
 
     def __open_connection(self):
         """Opens a new network connection."""
-        self.converter = self._converter_class(
+        self.converter = self.converter_class(
             use_numpy=self._numpy, support_negative_year=self._support_negative_year
         )