Add initial typings

.flake8

@@ -1,3 +1,5 @@
 [flake8]
+select = C90,E,F,W,Y0
 ignore = E402,E731,W503,W504,E252
-exclude = .git,__pycache__,build,dist,.eggs,.github,.local,.venv,.tox
+exclude = .git,__pycache__,build,dist,.eggs,.github,.local,.venv*,.tox
+per-file-ignores = *.pyi: F401,F403,F405,F811,E127,E128,E203,E266,E301,E302,E305,E501,E701,E704,E741,B303,W503,W504

.github/workflows/release.yml

@@ -22,7 +22,7 @@ jobs:
         github_token: ${{ secrets.RELEASE_BOT_GITHUB_TOKEN }}
         version_file: asyncpg/_version.py
         version_line_pattern: |
-          __version__\s*=\s*(?:['"])([[:PEP440:]])(?:['"])
+          __version__(?:\s*:\s*typing\.Final)?\s*=\s*(?:['"])([[:PEP440:]])(?:['"])
 
     - name: Stop if not approved
       if: steps.checkver.outputs.approved != 'true'

.gitignore

@@ -34,3 +34,5 @@ docs/_build
 /.eggs
 /.vscode
 /.mypy_cache
+/.venv*
+/.tox

MANIFEST.in

@@ -1,5 +1,5 @@
 recursive-include docs *.py *.rst Makefile *.css
 recursive-include examples *.py
 recursive-include tests *.py *.pem
-recursive-include asyncpg *.pyx *.pxd *.pxi *.py *.c *.h
+recursive-include asyncpg *.pyx *.pxd *.pxi *.py *.pyi *.c *.h
 include LICENSE README.rst Makefile performance.png .flake8

asyncpg/__init__.py

@@ -4,6 +4,7 @@
 # This module is part of asyncpg and is released under
 # the Apache 2.0 License: http://www.apache.org/licenses/LICENSE-2.0
 
+from __future__ import annotations
 
 from .connection import connect, Connection  # NOQA
 from .exceptions import *  # NOQA
@@ -14,6 +15,10 @@
 
 from ._version import __version__  # NOQA
 
+from . import exceptions
 
-__all__ = ('connect', 'create_pool', 'Pool', 'Record', 'Connection')
+
+__all__: tuple[str, ...] = (
+    'connect', 'create_pool', 'Pool', 'Record', 'Connection'
+)
 __all__ += exceptions.__all__ # NOQA

asyncpg/_asyncio_compat.py

@@ -4,18 +4,25 @@
 #
 # SPDX-License-Identifier: PSF-2.0
 
+from __future__ import annotations
 
 import asyncio
 import functools
 import sys
+import typing
+
+if typing.TYPE_CHECKING:
+    from . import compat
 
 if sys.version_info < (3, 11):
     from async_timeout import timeout as timeout_ctx
 else:
     from asyncio import timeout as timeout_ctx
 
+_T = typing.TypeVar('_T')
+
 
-async def wait_for(fut, timeout):
+async def wait_for(fut: compat.Awaitable[_T], timeout: float | None) -> _T:
     """Wait for the single Future or coroutine to complete, with timeout.
 
     Coroutine will be wrapped in Task.
@@ -65,7 +72,7 @@ async def wait_for(fut, timeout):
         return await fut
 
 
-async def _cancel_and_wait(fut):
+async def _cancel_and_wait(fut: asyncio.Future[_T]) -> None:
     """Cancel the *fut* future or task and wait until it completes."""
 
     loop = asyncio.get_running_loop()
@@ -82,6 +89,6 @@ async def _cancel_and_wait(fut):
         fut.remove_done_callback(cb)
 
 
-def _release_waiter(waiter, *args):
+def _release_waiter(waiter: asyncio.Future[typing.Any], *args: object) -> None:
     if not waiter.done():
         waiter.set_result(None)

asyncpg/_version.py

@@ -10,4 +10,8 @@
 # supported platforms, publish the packages on PyPI, merge the PR
 # to the target branch, create a Git tag pointing to the commit.
 
-__version__ = '0.30.0.dev0'
+from __future__ import annotations
+
+import typing
+
+__version__: typing.Final = '0.30.0.dev0'

asyncpg/compat.py

@@ -4,22 +4,25 @@
 # This module is part of asyncpg and is released under
 # the Apache 2.0 License: http://www.apache.org/licenses/LICENSE-2.0
 
+from __future__ import annotations
 
 import pathlib
 import platform
 import typing
 import sys
 
+if typing.TYPE_CHECKING:
+    import asyncio
 
-SYSTEM = platform.uname().system
+SYSTEM: typing.Final = platform.uname().system
 
 
-if SYSTEM == 'Windows':
+if sys.platform == 'win32':
     import ctypes.wintypes
 
-    CSIDL_APPDATA = 0x001a
+    CSIDL_APPDATA: typing.Final = 0x001a
 
-    def get_pg_home_directory() -> typing.Optional[pathlib.Path]:
+    def get_pg_home_directory() -> pathlib.Path | None:
         # We cannot simply use expanduser() as that returns the user's
         # home directory, whereas Postgres stores its config in
         # %AppData% on Windows.
@@ -31,14 +34,14 @@ def get_pg_home_directory() -> typing.Optional[pathlib.Path]:
             return pathlib.Path(buf.value) / 'postgresql'
 
 else:
-    def get_pg_home_directory() -> typing.Optional[pathlib.Path]:
+    def get_pg_home_directory() -> pathlib.Path | None:
         try:
             return pathlib.Path.home()
         except (RuntimeError, KeyError):
             return None
 
 
-async def wait_closed(stream):
+async def wait_closed(stream: asyncio.StreamWriter) -> None:
     # Not all asyncio versions have StreamWriter.wait_closed().
     if hasattr(stream, 'wait_closed'):
         try:
@@ -59,3 +62,12 @@ async def wait_closed(stream):
     from ._asyncio_compat import timeout_ctx as timeout  # noqa: F401
 else:
     from asyncio import timeout as timeout  # noqa: F401
+
+if sys.version_info < (3, 9):
+    from typing import (  # noqa: F401
+        Awaitable as Awaitable,
+    )
+else:
+    from collections.abc import (  # noqa: F401
+        Awaitable as Awaitable,
+    )

asyncpg/introspection.py

@@ -4,8 +4,14 @@
 # This module is part of asyncpg and is released under
 # the Apache 2.0 License: http://www.apache.org/licenses/LICENSE-2.0
 
+from __future__ import annotations
 
-_TYPEINFO_13 = '''\
+import typing
+
+if typing.TYPE_CHECKING:
+    from . import protocol
+
+_TYPEINFO_13: typing.Final = '''\
     (
         SELECT
             t.oid                           AS oid,
@@ -124,7 +130,7 @@
 '''.format(typeinfo=_TYPEINFO_13)
 
 
-_TYPEINFO = '''\
+_TYPEINFO: typing.Final = '''\
     (
         SELECT
             t.oid                           AS oid,
@@ -248,7 +254,7 @@
 '''.format(typeinfo=_TYPEINFO)
 
 
-TYPE_BY_NAME = '''\
+TYPE_BY_NAME: typing.Final = '''\
 SELECT
     t.oid,
     t.typelem     AS elemtype,
@@ -277,16 +283,16 @@
 SCALAR_TYPE_KINDS = (b'b', b'd', b'e')
 
 
-def is_scalar_type(typeinfo) -> bool:
+def is_scalar_type(typeinfo: protocol.Record) -> bool:
     return (
         typeinfo['kind'] in SCALAR_TYPE_KINDS and
         not typeinfo['elemtype']
     )
 
 
-def is_domain_type(typeinfo) -> bool:
-    return typeinfo['kind'] == b'd'
+def is_domain_type(typeinfo: protocol.Record) -> bool:
+    return typeinfo['kind'] == b'd'  # type: ignore[no-any-return]
 
 
-def is_composite_type(typeinfo) -> bool:
-    return typeinfo['kind'] == b'c'
+def is_composite_type(typeinfo: protocol.Record) -> bool:
+    return typeinfo['kind'] == b'c'  # type: ignore[no-any-return]

asyncpg/protocol/__init__.py

@@ -6,4 +6,6 @@
 
 # flake8: NOQA
 
+from __future__ import annotations
+
 from .protocol import Protocol, Record, NO_TIMEOUT, BUILTIN_TYPE_NAME_MAP