Drop support of Python 3.8

.devcontainer/Dockerfile

@@ -2,7 +2,7 @@ FROM python:3.11-slim
 
 ENV PATH=$PATH:/root/.local/bin
 ENV POETRY_VIRTUALENVS_CREATE=false
-ENV POETRY_VERSION=1.2.2
+ENV POETRY_VERSION=1.6.1
 
 RUN apt-get update \
     && apt-get install -y curl git \

.github/workflows/tests.yml

@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ["3.8", "3.9", "3.10", "3.11"]
+        python: ["3.9", "3.10", "3.11"]
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-python@v4
@@ -34,5 +34,5 @@ jobs:
       - name: Test code's execution (pytest)
         run: pytest -v tests
       - name: Test docs' building (Sphinx)
-        if: ${{ contains('3.10, 3.11', matrix.python) }}
+        if: ${{ matrix.python != '3.9' }}
         run: docs/build

pandas_dataclasses/core/api.py

@@ -3,7 +3,7 @@
 
 # standard library
 from types import FunctionType
-from typing import Any, Callable, Dict, Hashable, Iterable, Optional, Tuple, overload
+from typing import Any, Callable, Hashable, Iterable, Optional, overload
 
 
 # dependencies
@@ -193,9 +193,9 @@ def asseries(obj: Any, *, factory: Any = None) -> Any:
     return squeeze(series)
 
 
-def get_attrs(spec: Spec) -> Dict[Hashable, Any]:
+def get_attrs(spec: Spec) -> dict[Hashable, Any]:
     """Derive attributes from a specification."""
-    data: Dict[Hashable, Any] = {}
+    data: dict[Hashable, Any] = {}
 
     for field in spec.fields.of(Tag.ATTR):
         data.update(items(field))
@@ -217,9 +217,9 @@ def get_columns(spec: Spec) -> Optional[pd.MultiIndex]:
     )
 
 
-def get_data(spec: Spec) -> Dict[Hashable, Any]:
+def get_data(spec: Spec) -> dict[Hashable, Any]:
     """Derive data from a specification."""
-    data: Dict[Hashable, Any] = {}
+    data: dict[Hashable, Any] = {}
 
     for field in spec.fields.of(Tag.DATA):
         for key, val in items(field):
@@ -233,7 +233,7 @@ def get_index(spec: Spec) -> Optional[pd.MultiIndex]:
     if not (fields := spec.fields.of(Tag.INDEX)):
         return None
 
-    data: Dict[Hashable, Any] = {}
+    data: dict[Hashable, Any] = {}
 
     for field in fields:
         for key, val in items(field):
@@ -251,12 +251,12 @@ def ensure(data: Any, dtype: Optional[str]) -> Any:
         data = [data]
 
     if isinstance(data, (pd.Index, pd.Series)):
-        return type(data)(data, dtype=dtype, copy=False)
+        return type(data)(data, dtype=dtype, copy=False)  # type: ignore
     else:
         return pd.array(data, dtype=dtype, copy=False)
 
 
-def items(field: Field) -> Iterable[Tuple[Hashable, Any]]:
+def items(field: Field) -> Iterable[tuple[Hashable, Any]]:
     """Generate default(s) of a field specification."""
     if field.has(Tag.MULTIPLE):
         yield from field.default.items()

pandas_dataclasses/core/specs.py

@@ -5,7 +5,7 @@
 from dataclasses import Field as Field_, dataclass, fields as fields_, replace
 from functools import lru_cache
 from itertools import repeat
-from typing import Any, Callable, Hashable, Literal, Optional, Tuple, Union
+from typing import Any, Callable, Hashable, Literal, Optional, Union
 
 
 # dependencies
@@ -25,7 +25,7 @@ class Field:
     name: Union[Hashable, HashDict]
     """Name of the field data."""
 
-    tags: Tuple[Tag, ...] = ()
+    tags: tuple[Tag, ...] = ()
     """Tags of the field."""
 
     type: Optional[Any] = None
@@ -50,7 +50,7 @@ def update(self, obj: Any) -> Self:
         )
 
 
-class Fields(Tuple[Field, ...]):
+class Fields(tuple[Field, ...]):
     """List of field specifications with selectors."""
 
     def of(self, tag: Tag) -> Self:
@@ -104,7 +104,7 @@ def __matmul__(self, obj: Any) -> Self:
 
 
 @lru_cache(maxsize=None)
-def convert_field(field_: "Field_[Any]") -> Field:
+def convert_field(field_: Field_[Any]) -> Field:
     """Convert a dataclass field to a field specification."""
     return Field(
         id=field_.name,

pandas_dataclasses/core/tagging.py

@@ -6,11 +6,11 @@
 from functools import reduce
 from itertools import chain, filterfalse
 from operator import or_
-from typing import Any, Iterable, Optional, Tuple
+from typing import Annotated, Any, Iterable, Optional
 
 
 # dependencies
-from typing_extensions import Annotated, Self, TypeGuard, get_args, get_origin
+from typing_extensions import Self, TypeGuard, get_args, get_origin
 
 
 class Tag(Flag):
@@ -80,13 +80,13 @@ def get_tagged(
         return tagged if keep_annotations else get_args(tagged)[0]
 
 
-def get_tags(tp: Any, bound: Tag = Tag.ANY) -> Tuple[Tag, ...]:
+def get_tags(tp: Any, bound: Tag = Tag.ANY) -> tuple[Tag, ...]:
     """Extract all tags from the first tagged type."""
     tagged = get_tagged(tp, bound, True)
     return tuple(filter(Tag.creates, get_args(tagged)[1:]))
 
 
-def get_nontags(tp: Any, bound: Tag = Tag.ANY) -> Tuple[Any, ...]:
+def get_nontags(tp: Any, bound: Tag = Tag.ANY) -> tuple[Any, ...]:
     """Extract all except tags from the first tagged type."""
     tagged = get_tagged(tp, bound, True)
     return tuple(filterfalse(Tag.creates, get_args(tagged)[1:]))

pandas_dataclasses/core/typing.py

@@ -15,15 +15,15 @@
 # standard library
 import types
 from dataclasses import Field
-from typing import Any, Callable, ClassVar, Dict, Hashable, Protocol, TypeVar, Union
+from typing import Any, Callable, ClassVar, Hashable, Protocol, TypeVar, Union
 
 
 # dependencies
 from pandas import DataFrame, Series
 from typing_extensions import ParamSpec, get_origin
 
 
-HashDict = Dict[Hashable, Hashable]
+HashDict = dict[Hashable, Hashable]
 """Type hint for dictionary of hashable keys and values."""
 
 Pandas = Union[DataFrame, "Series[Any]"]
@@ -48,7 +48,7 @@
 class DataClass(Protocol[PAny]):
     """Protocol for any dataclass object."""
 
-    __dataclass_fields__: ClassVar[Dict[str, "Field[Any]"]]
+    __dataclass_fields__: ClassVar[dict[str, Field[Any]]]
 
     def __init__(self, *args: PAny.args, **kwargs: PAny.kwargs) -> None:
         ...
@@ -57,7 +57,7 @@ def __init__(self, *args: PAny.args, **kwargs: PAny.kwargs) -> None:
 class DataClassOf(Protocol[TPandas, PAny]):
     """Protocol for any dataclass object with a factory."""
 
-    __dataclass_fields__: ClassVar[Dict[str, "Field[Any]"]]
+    __dataclass_fields__: ClassVar[dict[str, Field[Any]]]
     __pandas_factory__: Callable[..., TPandas]
 
     def __init__(self, *args: PAny.args, **kwargs: PAny.kwargs) -> None:

pandas_dataclasses/extras/hints.py

@@ -2,11 +2,10 @@
 
 
 # standard library
-from typing import Collection, Dict, Hashable
+from typing import Annotated, Collection
 
 
 # dependencies
-from typing_extensions import Annotated
 from ..core.tagging import Tag
 from ..core.typing import TAny
 
@@ -21,5 +20,5 @@
 Index = Annotated[Collection[Annotated[TAny, Tag.DTYPE]], Tag.INDEX]
 """Type hint for index fields (``Index[TAny]``)."""
 
-Multiple = Dict[Hashable, Annotated[TAny, Tag.MULTIPLE]]
+Multiple = dict[str, Annotated[TAny, Tag.MULTIPLE]]
 """Type hint for multiple-item fields (``Multiple[TAny]``)."""

pandas_dataclasses/extras/new.py

@@ -4,7 +4,7 @@
 # standard library
 from inspect import signature
 from types import MethodType
-from typing import Any, Callable, ForwardRef, Generic, Type, Union
+from typing import Any, Callable, ForwardRef, Generic, Union
 
 
 # dependencies
@@ -23,7 +23,7 @@ def __init__(self, fget: Callable[..., Any]) -> None:
     def __get__(
         self,
         obj: Any,
-        cls: Type[DataClassOf[TPandas, PAny]],
+        cls: type[DataClassOf[TPandas, PAny]],
     ) -> Callable[PAny, TPandas]:
         return self.fget(cls)  # type: ignore
 
@@ -77,7 +77,7 @@ def get_factory(cls: Any) -> Callable[..., Any]:
     raise TypeError("Factory must be callable.")
 
 
-def get_return(cls: Any) -> Union[Type[Any], str]:
+def get_return(cls: Any) -> Union[type[Any], str]:
     """Extract a return type from a class."""
     for base in getattr(cls, "__orig_bases__", ()):
         if get_origin(base) is not As: