refactor: Python version conditions typing imports

Author: Rogdham

CHANGELOG.md

@@ -20,6 +20,7 @@ adheres to [Semantic Versioning](https://semver.org/).
 - Add tests for CPython 3.11 and PyPy 3.9
 - Use CPython 3.11 for misc. tests
 - Update Github actions dependencies
+- Import typing modules impacted by PEP 585 based on Python version
 
 ## [0.4.0] - 2022-01-09
 

setup.cfg

@@ -36,3 +36,5 @@ python_requires = >=3.7
 setup_requires =
     setuptools_scm
     wheel
+install_requires =
+    typing-extensions>=4.5.0;python_version<"3.8"

src/xz/block.py

@@ -1,6 +1,6 @@
 from io import DEFAULT_BUFFER_SIZE, SEEK_SET
 from lzma import FORMAT_XZ, LZMACompressor, LZMADecompressor, LZMAError
-from typing import Tuple, Union
+from typing import Optional, Tuple, Union
 
 from xz.common import (
     XZError,
@@ -11,12 +11,7 @@
 )
 from xz.io import IOAbstract, IOCombiner, IOStatic
 from xz.strategy import KeepBlockReadStrategy
-from xz.typing import (
-    Optional,
-    _BlockReadStrategyType,
-    _LZMAFiltersType,
-    _LZMAPresetType,
-)
+from xz.typing import _BlockReadStrategyType, _LZMAFiltersType, _LZMAPresetType
 
 
 class BlockRead:

src/xz/stream.py

@@ -1,5 +1,5 @@
 from io import SEEK_CUR
-from typing import BinaryIO, List
+from typing import BinaryIO, List, Optional
 
 from xz.block import XZBlock
 from xz.common import (
@@ -12,12 +12,7 @@
     round_up,
 )
 from xz.io import IOCombiner, IOProxy
-from xz.typing import (
-    Optional,
-    _BlockReadStrategyType,
-    _LZMAFiltersType,
-    _LZMAPresetType,
-)
+from xz.typing import _BlockReadStrategyType, _LZMAFiltersType, _LZMAPresetType
 
 
 class XZStream(IOCombiner[XZBlock]):

src/xz/typing.py

@@ -1,24 +1,22 @@
 from os import PathLike
 import sys
-from typing import TYPE_CHECKING, Any, BinaryIO, Mapping, Optional, Sequence, Union
+from typing import TYPE_CHECKING, Any, BinaryIO, Optional, Union
 
 if sys.version_info >= (3, 9):  # pragma: no cover
+    from collections.abc import Mapping, Sequence
+
     _LZMAFilenameType = Union[str, bytes, PathLike[str], PathLike[bytes], BinaryIO]
-    from typing import Literal
 else:  # pragma: no cover
-    _LZMAFilenameType = Union[str, bytes, PathLike, BinaryIO]
+    from typing import Mapping, Sequence
 
-    class Literal:
-        def __class_getitem__(cls, items: Any) -> str:
-            return f"Literal{list(items)}"
+    _LZMAFilenameType = Union[str, bytes, PathLike, BinaryIO]
 
 
 if sys.version_info >= (3, 8):  # pragma: no cover
-    from typing import Protocol
+    from typing import Literal, Protocol
 else:  # pragma: no cover
-    # ducktype Protocol
-    # we could require typing-extensions package instead
-    Protocol = object
+    from typing_extensions import Literal, Protocol
+
 
 if TYPE_CHECKING:  # pragma: no cover
     # avoid circular dependency

src/xz/utils.py

@@ -1,19 +1,17 @@
 from bisect import bisect_right, insort_right
-from collections.abc import MutableMapping
 import sys
-from typing import Any, Dict, Generic, Iterator, List
-from typing import MutableMapping as TypingMutableMapping
-from typing import Tuple, TypeVar, cast
-
-T = TypeVar("T")
+from typing import Any, Dict, Generic, List, Tuple, TypeVar, cast
 
 if sys.version_info >= (3, 9):  # pragma: no cover
-    _MutableMapping = MutableMapping
+    from collections.abc import Iterator, MutableMapping
 else:  # pragma: no cover
-    _MutableMapping = TypingMutableMapping
+    from typing import Iterator, MutableMapping
+
+
+T = TypeVar("T")
 
 
-class FloorDict(_MutableMapping[int, T]):
+class FloorDict(MutableMapping[int, T]):
     """A dict where keys are int, and accessing a key will use the closest lower one.
 
     Differences from dict:

tests/conftest.py

@@ -1,9 +1,15 @@
 from itertools import chain, product
 from pathlib import Path
-from typing import Callable, Iterator, List, Tuple
+import sys
+from typing import List, Tuple
 
 import pytest
 
+if sys.version_info >= (3, 9):  # pragma: no cover
+    from collections.abc import Callable, Iterator
+else:  # pragma: no cover
+    from typing import Callable, Iterator
+
 
 def pytest_addoption(parser: pytest.Parser) -> None:
     parser.addoption(

tests/integration/test_ram_usage.py

@@ -3,7 +3,7 @@
 from pathlib import Path
 from random import seed
 import sys
-from typing import BinaryIO, Callable, Iterator, Optional, cast
+from typing import BinaryIO, Optional, cast
 
 import pytest
 
@@ -12,9 +12,11 @@
 from xz.io import IOCombiner, IOStatic
 
 if sys.version_info >= (3, 9):
+    from collections.abc import Callable, Iterator
     from random import randbytes
 else:
     from random import getrandbits
+    from typing import Callable, Iterator
 
     def randbytes(length: int) -> bytes:
         return getrandbits(length * 8).to_bytes(length, "little")

tests/integration/test_readme.py

@@ -2,12 +2,18 @@
 import os
 from pathlib import Path
 import shutil
-from typing import Iterator, List, Optional, Tuple
+import sys
+from typing import List, Optional, Tuple
 
 import pytest
 
 import xz
 
+if sys.version_info >= (3, 9):  # pragma: no cover
+    from collections.abc import Iterator
+else:  # pragma: no cover
+    from typing import Iterator
+
 
 @pytest.fixture(autouse=True)
 def change_dir(tmp_path: Path) -> Iterator[None]:

tests/unit/test_block.py

@@ -1,5 +1,6 @@
 from io import SEEK_SET, BytesIO, UnsupportedOperation
-from typing import Callable, Iterator, Tuple, cast
+import sys
+from typing import Tuple, cast
 from unittest.mock import Mock, call
 
 import pytest
@@ -9,6 +10,12 @@
 from xz.common import XZError, create_xz_header, create_xz_index_footer
 from xz.io import IOAbstract, IOStatic
 
+if sys.version_info >= (3, 9):  # pragma: no cover
+    from collections.abc import Callable, Iterator
+else:  # pragma: no cover
+    from typing import Callable, Iterator
+
+
 BLOCK_BYTES = bytes.fromhex(
     "0200210116000000742fe5a3e0006300415d00209842100431d01ab285328305"
     "7ddb5924a128599cc9911a7fcff8d59c1f6f887bcee97b1f83f1808f005de273"