general: switch to using native 3.8 versions for cached_property/Literal/Protocol instead of compat

my/core/common.py

@@ -366,10 +366,6 @@ def isoparse(s: str) -> tzdatetime:
     return datetime.fromisoformat(s)
 
 
-# legacy import -- we should use compat directly instead
-from .compat import Literal
-
-
 import re
 # https://stackoverflow.com/a/295466/706389
 def get_valid_filename(s: str) -> str:
@@ -664,5 +660,7 @@ def assert_never(value: NoReturn) -> NoReturn:
     assert False, f'Unhandled value: {value} ({type(value).__name__})'
 
 
-# legacy deprecated import
-from .compat import cached_property as cproperty
+## legacy imports, keeping them here for backwards compatibility
+from functools import cached_property as cproperty
+from typing import Literal
+## 

my/core/compat.py

@@ -3,6 +3,7 @@ Some backwards compatibility stuff/deprecation helpers
 '''
 import sys
 from types import ModuleType
+from typing import TYPE_CHECKING
 
 from . import warnings
 from .common import LazyLogger
@@ -53,20 +54,10 @@ import os
 windows = os.name == 'nt'
 
 
+# keeping just for backwards compatibility, used to have compat implementation for 3.6
 import sqlite3
 def sqlite_backup(*, source: sqlite3.Connection, dest: sqlite3.Connection, **kwargs) -> None:
-    if sys.version_info[:2] >= (3, 7):
-        source.backup(dest, **kwargs)
-    else:
-        # https://stackoverflow.com/a/10856450/706389
-        import io
-        tempfile = io.StringIO()
-        for line in source.iterdump():
-            tempfile.write('%s\n' % line)
-        tempfile.seek(0)
-
-        dest.cursor().executescript(tempfile.read())
-        dest.commit()
+    source.backup(dest, **kwargs)
 
 
 # can remove after python3.9
@@ -76,55 +67,10 @@ def removeprefix(text: str, prefix: str) -> str:
     return text
 
 
-# can remove after python3.8
-if sys.version_info[:2] >= (3, 8):
-    from functools import cached_property
-else:
-    from typing import TypeVar, Callable
-    Cl = TypeVar('Cl')
-    R = TypeVar('R')
-
-    def cached_property(f: Callable[[Cl], R]) -> R:
-        import functools
-        return property(functools.lru_cache(maxsize=1)(f))
-    del Cl
-    del R
-
-
-from typing import TYPE_CHECKING
-
-
-if sys.version_info[:2] >= (3, 8):
-    from typing import Literal
-else:
-    if TYPE_CHECKING:
-        from typing_extensions import Literal
-    else:
-        # erm.. I guess as long as it's not crashing, whatever...
-        class _Literal:
-            def __getitem__(self, args):
-                pass
-        Literal = _Literal()
-
-
-if sys.version_info[:2] >= (3, 8):
-    from typing import Protocol
-else:
-    if TYPE_CHECKING:
-        from typing_extensions import Protocol
-    else:
-        # todo could also use NamedTuple?
-        Protocol = object
-
-
-if sys.version_info[:2] >= (3, 8):
-    from typing import TypedDict
-else:
-    if TYPE_CHECKING:
-        from typing_extensions import TypedDict
-    else:
-        from typing import Dict
-        TypedDict = Dict
+## used to have compat function before 3.8 for these
+from functools import cached_property
+from typing import Literal, Protocol, TypedDict
+##
 
 
 if sys.version_info[:2] >= (3, 10):

my/core/dataset.py

@@ -2,11 +2,10 @@ from __future__ import annotations
 from .common import assert_subpackage; assert_subpackage(__name__)
 
 from .common import PathIsh
-from .compat import Protocol
 from .sqlite import sqlite_connect_immutable
 
 ## sadly dataset doesn't have any type definitions
-from typing import Iterable, Iterator, Dict, Optional, Any
+from typing import Iterable, Iterator, Dict, Optional, Any, Protocol
 from contextlib import AbstractContextManager
 
 

my/core/error.py

@@ -4,9 +4,7 @@ See https://beepb00p.xyz/mypy-error-handling.html#kiss for more detail
 """
 
 from itertools import tee
-from typing import Union, TypeVar, Iterable, List, Tuple, Type, Optional, Callable, Any, cast, Iterator
-
-from .compat import Literal
+from typing import Union, TypeVar, Iterable, List, Tuple, Type, Optional, Callable, Any, cast, Iterator, Literal
 
 
 T = TypeVar('T')

my/core/pandas.py

@@ -5,7 +5,7 @@ Various pandas helpers and convenience functions
 # NOTE: this file is meant to be importable without Pandas installed
 from datetime import datetime
 from pprint import pformat
-from typing import Optional, TYPE_CHECKING, Any, Iterable, Type, Dict
+from typing import Optional, TYPE_CHECKING, Any, Iterable, Type, Dict, Literal
 from . import warnings, Res
 from .common import LazyLogger, Json, asdict
 
@@ -45,8 +45,6 @@ def check_dateish(s) -> Iterable[str]:
     '''.strip()
 
 
-from .compat import Literal
-
 ErrorColPolicy = Literal[
     'add_if_missing', # add error column if it's missing
     'warn'          , # warn, but do not modify

my/core/sqlite.py

@@ -6,11 +6,10 @@ from pathlib import Path
 import shutil
 import sqlite3
 from tempfile import TemporaryDirectory
-from typing import Tuple, Any, Iterator, Callable, Optional, Union
+from typing import Tuple, Any, Iterator, Callable, Optional, Union, Literal
 
 
 from .common import PathIsh, assert_never
-from .compat import Literal
 
 
 def sqlite_connect_immutable(db: PathIsh) -> sqlite3.Connection:
@@ -86,8 +85,7 @@ def sqlite_copy_and_open(db: PathIsh) -> sqlite3.Connection:
         for p in tocopy:
             shutil.copy(p, tdir / p.name)
         with sqlite3.connect(str(tdir / dp.name)) as conn:
-            from .compat import sqlite_backup
-            sqlite_backup(source=conn, dest=dest)
+            conn.backup(target=dest)
         conn.close()
     return dest