Python's 3.9 compatible typing annotations

pint/_typing.py

@@ -19,10 +19,10 @@
 if HAS_NUMPY:
     from .compat import np
 
-    Scalar = Union[float, int, Decimal, Fraction, np.number[Any]]
+    Scalar: TypeAlias = Union[float, int, Decimal, Fraction, np.number[Any]]
     Array = np.ndarray[Any, Any]
 else:
-    Scalar = Union[float, int, Decimal, Fraction]
+    Scalar: TypeAlias = Union[float, int, Decimal, Fraction]
     Array: TypeAlias = Never
 
 # TODO: Change when Python 3.10 becomes minimal version.

pint/compat.py

@@ -18,7 +18,7 @@
 from io import BytesIO
 from numbers import Number
 from collections.abc import Mapping
-from typing import Any, NoReturn, Callable
+from typing import Any, NoReturn, Callable, Optional, Union
 from collections.abc import Generator, Iterable
 
 
@@ -41,7 +41,7 @@
 
 
 def missing_dependency(
-    package: str, display_name: str | None = None
+    package: str, display_name: Optional[str] = None
 ) -> Callable[..., NoReturn]:
     """Return a helper function that raises an exception when used.
 
@@ -225,7 +225,7 @@ def _to_magnitude(value, force_ndarray=False, force_ndarray_like=False):
 )
 
 #: Map type name to the actual type (for upcast types).
-upcast_type_map: Mapping[str, type | None] = {k: None for k in upcast_type_names}
+upcast_type_map: Mapping[str, Optional[type]] = {k: None for k in upcast_type_names}
 
 
 def fully_qualified_name(t: type) -> str:
@@ -286,7 +286,7 @@ def is_duck_array(obj: type) -> bool:
     return is_duck_array_type(type(obj))
 
 
-def eq(lhs: Any, rhs: Any, check_all: bool) -> bool | Iterable[bool]:
+def eq(lhs: Any, rhs: Any, check_all: bool) -> Union[bool, Iterable[bool]]:
     """Comparison of scalars and arrays.
 
     Parameters
@@ -309,7 +309,7 @@ def eq(lhs: Any, rhs: Any, check_all: bool) -> bool | Iterable[bool]:
     return out
 
 
-def isnan(obj: Any, check_all: bool) -> bool | Iterable[bool]:
+def isnan(obj: Any, check_all: bool) -> Union[bool, Iterable[bool]]:
     """Test for NaN or NaT.
 
     Parameters
@@ -342,7 +342,7 @@ def isnan(obj: Any, check_all: bool) -> bool | Iterable[bool]:
         return False
 
 
-def zero_or_nan(obj: Any, check_all: bool) -> bool | Iterable[bool]:
+def zero_or_nan(obj: Any, check_all: bool) -> Union[bool, Iterable[bool]]:
     """Test if obj is zero, NaN, or NaT.
 
     Parameters

pint/converters.py

@@ -13,7 +13,7 @@
 from dataclasses import dataclass
 from dataclasses import fields as dc_fields
 
-from typing import Any
+from typing import Any, Optional
 
 from ._typing import Magnitude
 
@@ -53,7 +53,7 @@ def get_field_names(cls, new_cls: type) -> frozenset[str]:
         return frozenset(p.name for p in dc_fields(new_cls))
 
     @classmethod
-    def preprocess_kwargs(cls, **kwargs: Any) -> dict[str, Any] | None:
+    def preprocess_kwargs(cls, **kwargs: Any) -> Optional[dict[str, Any]]:
         return None
 
     @classmethod

pint/delegates/txt_defparser/context.py

@@ -19,6 +19,7 @@
 import numbers
 import re
 import typing as ty
+from typing import Optional, Union
 from dataclasses import dataclass
 
 from ..._vendor import flexparser as fp
@@ -27,12 +28,12 @@
 from . import block, common, plain
 
 # TODO check syntax
-T = ty.TypeVar("T", bound="ForwardRelation | BidirectionalRelation")
+T = ty.TypeVar("T", bound="Union[ForwardRelation, BidirectionalRelation]")
 
 
 def _from_string_and_context_sep(
     cls: type[T], s: str, config: ParserConfig, separator: str
-) -> T | None:
+) -> Optional[T]:
     if separator not in s:
         return None
     if ":" not in s:
@@ -199,7 +200,7 @@ def defaults(self) -> dict[str, numbers.Number]:
         return self.opening.defaults
 
     @property
-    def relations(self) -> tuple[BidirectionalRelation | ForwardRelation, ...]:
+    def relations(self) -> tuple[Union[BidirectionalRelation, ForwardRelation], ...]:
         return tuple(
             r
             for r in self.body

pint/delegates/txt_defparser/defparser.py

@@ -2,6 +2,7 @@
 
 import pathlib
 import typing as ty
+from typing import Optional, Union
 
 from ..._vendor import flexcache as fc
 from ..._vendor import flexparser as fp
@@ -130,15 +131,17 @@ def iter_parsed_project(self, parsed_project: fp.ParsedProject):
             else:
                 yield stmt
 
-    def parse_file(self, filename: pathlib.Path | str, cfg: ParserConfig | None = None):
+    def parse_file(
+        self, filename: Union[pathlib.Path, str], cfg: Optional[ParserConfig] = None
+    ):
         return fp.parse(
             filename,
             _PintParser,
             cfg or self._default_config,
             diskcache=self._diskcache,
         )
 
-    def parse_string(self, content: str, cfg: ParserConfig | None = None):
+    def parse_string(self, content: str, cfg: Optional[ParserConfig] = None):
         return fp.parse_bytes(
             content.encode("utf-8"),
             _PintParser,

pint/errors.py

@@ -10,6 +10,7 @@
 
 from __future__ import annotations
 
+from typing import Union
 import typing as ty
 from dataclasses import dataclass, fields
 
@@ -134,7 +135,7 @@ def __reduce__(self):
 class UndefinedUnitError(AttributeError, PintError):
     """Raised when the units are not defined in the unit registry."""
 
-    unit_names: str | tuple[str, ...]
+    unit_names: Union[str, tuple[str, ...]]
 
     def __str__(self):
         if isinstance(self.unit_names, str):

pint/facets/context/objects.py

@@ -10,7 +10,7 @@
 
 import weakref
 from collections import ChainMap, defaultdict
-from typing import Any, Callable, Protocol, Generic
+from typing import Any, Callable, Protocol, Generic, Optional
 from collections.abc import Iterable
 
 from ...facets.plain import UnitDefinition, PlainQuantity, PlainUnit, MagnitudeT
@@ -91,11 +91,11 @@ class Context:
 
     def __init__(
         self,
-        name: str | None = None,
+        name: Optional[str] = None,
         aliases: tuple[str, ...] = tuple(),
-        defaults: dict[str, Any] | None = None,
+        defaults: Optional[dict[str, Any]] = None,
     ) -> None:
-        self.name: str | None = name
+        self.name: Optional[str] = name
         self.aliases: tuple[str, ...] = aliases
 
         #: Maps (src, dst) -> transformation function
@@ -150,7 +150,7 @@ def from_context(cls, context: Context, **defaults: Any) -> Context:
     def from_lines(
         cls,
         lines: Iterable[str],
-        to_base_func: ToBaseFunc | None = None,
+        to_base_func: Optional[ToBaseFunc] = None,
         non_int_type: type = float,
     ) -> Context:
         context_definition = ContextDefinition.from_lines(lines, non_int_type)
@@ -162,7 +162,7 @@ def from_lines(
 
     @classmethod
     def from_definition(
-        cls, cd: ContextDefinition, to_base_func: ToBaseFunc | None = None
+        cls, cd: ContextDefinition, to_base_func: Optional[ToBaseFunc] = None
     ) -> Context:
         ctx = cls(cd.name, cd.aliases, cd.defaults)
 
@@ -241,7 +241,7 @@ def _redefine(self, definition: UnitDefinition):
     def hashable(
         self,
     ) -> tuple[
-        str | None,
+        Optional[str],
         tuple[str, ...],
         frozenset[tuple[SrcDst, int]],
         frozenset[tuple[str, Any]],
@@ -273,7 +273,7 @@ def __init__(self):
         super().__init__()
         self.contexts: list[Context] = []
         self.maps.clear()  # Remove default empty map
-        self._graph: dict[SrcDst, set[UnitsContainer]] | None = None
+        self._graph: Optional[dict[SrcDst, set[UnitsContainer]]] = None
 
     def insert_contexts(self, *contexts: Context):
         """Insert one or more contexts in reversed order the chained map.
@@ -287,7 +287,7 @@ def insert_contexts(self, *contexts: Context):
         self.maps = [ctx.relation_to_context for ctx in reversed(contexts)] + self.maps
         self._graph = None
 
-    def remove_contexts(self, n: int | None = None):
+    def remove_contexts(self, n: Optional[int] = None):
         """Remove the last n inserted contexts from the chain.
 
         Parameters

pint/facets/context/registry.py

@@ -11,7 +11,7 @@
 import functools
 from collections import ChainMap
 from contextlib import contextmanager
-from typing import Any, Callable, Generator, Generic
+from typing import Any, Callable, Generator, Generic, Optional, Union
 
 from ...compat import TypeAlias
 from ..._typing import F, Magnitude
@@ -74,7 +74,7 @@ def _register_definition_adders(self) -> None:
         super()._register_definition_adders()
         self._register_adder(ContextDefinition, self.add_context)
 
-    def add_context(self, context: objects.Context | ContextDefinition) -> None:
+    def add_context(self, context: Union[objects.Context, ContextDefinition]) -> None:
         """Add a context object to the registry.
 
         The context will be accessible by its name and aliases.
@@ -197,7 +197,7 @@ def _redefine(self, definition: UnitDefinition) -> None:
         self.define(definition)
 
     def enable_contexts(
-        self, *names_or_contexts: str | objects.Context, **kwargs: Any
+        self, *names_or_contexts: Union[str, objects.Context], **kwargs: Any
     ) -> None:
         """Enable contexts provided by name or by object.
 
@@ -244,7 +244,7 @@ def enable_contexts(
         self._active_ctx.insert_contexts(*contexts)
         self._switch_context_cache_and_units()
 
-    def disable_contexts(self, n: int | None = None) -> None:
+    def disable_contexts(self, n: Optional[int] = None) -> None:
         """Disable the last n enabled contexts.
 
         Parameters
@@ -403,7 +403,7 @@ def _convert(
         return super()._convert(value, src, dst, inplace)
 
     def _get_compatible_units(
-        self, input_units: UnitsContainer, group_or_system: str | None = None
+        self, input_units: UnitsContainer, group_or_system: Optional[str] = None
     ):
         src_dim = self._get_dimensionality(input_units)
 

pint/facets/group/definitions.py

@@ -10,6 +10,7 @@
 
 from collections.abc import Iterable
 from dataclasses import dataclass
+from typing import Optional
 
 from ...compat import Self
 from ... import errors
@@ -30,7 +31,7 @@ class GroupDefinition(errors.WithDefErr):
     @classmethod
     def from_lines(
         cls: type[Self], lines: Iterable[str], non_int_type: type
-    ) -> Self | None:
+    ) -> Optional[Self]:
         # TODO: this is to keep it backwards compatible
         from ...delegates import ParserConfig, txt_defparser
 

pint/facets/group/objects.py

@@ -8,7 +8,7 @@
 
 from __future__ import annotations
 
-from typing import Callable, Any, TYPE_CHECKING, Generic
+from typing import Callable, Any, TYPE_CHECKING, Generic, Optional
 
 from collections.abc import Generator, Iterable
 from ...util import SharedRegistryObject, getattr_maybe_raise
@@ -81,7 +81,7 @@ def __init__(self, name: str):
 
         #: A cache of the included units.
         #: None indicates that the cache has been invalidated.
-        self._computed_members: frozenset[str] | None = None
+        self._computed_members: Optional[frozenset[str]] = None
 
     @property
     def members(self) -> frozenset[str]:
@@ -195,7 +195,9 @@ def from_lines(
 
     @classmethod
     def from_definition(
-        cls, group_definition: GroupDefinition, add_unit_func: AddUnitFunc | None = None
+        cls,
+        group_definition: GroupDefinition,
+        add_unit_func: Optional[AddUnitFunc] = None,
     ) -> Group:
         grp = cls(group_definition.name)
 

pint/facets/group/registry.py

@@ -8,7 +8,7 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Generic, Any
+from typing import TYPE_CHECKING, Generic, Any, Optional
 
 from ...compat import TypeAlias
 from ... import errors
@@ -47,7 +47,6 @@ class GenericGroupRegistry(
     def __init__(self, **kwargs):
         super().__init__(**kwargs)
         #: Map group name to group.
-        #: :type: dict[ str | Group]
         self._groups: dict[str, objects.Group] = {}
         self._groups["root"] = self.Group("root")
 
@@ -122,7 +121,7 @@ def get_group(self, name: str, create_if_needed: bool = True) -> objects.Group:
         return self.Group(name)
 
     def get_compatible_units(
-        self, input_units: UnitsContainer, group: str | None = None
+        self, input_units: UnitsContainer, group: Optional[str] = None
     ) -> frozenset[Unit]:
         """ """
         if group is None:
@@ -135,7 +134,7 @@ def get_compatible_units(
         return frozenset(self.Unit(eq) for eq in equiv)
 
     def _get_compatible_units(
-        self, input_units: UnitsContainer, group: str | None = None
+        self, input_units: UnitsContainer, group: Optional[str] = None
     ) -> frozenset[str]:
         ret = super()._get_compatible_units(input_units)
 

pint/facets/nonmultiplicative/objects.py

@@ -8,7 +8,7 @@
 
 from __future__ import annotations
 
-from typing import Generic
+from typing import Generic, Optional
 
 from ..plain import PlainQuantity, PlainUnit, MagnitudeT
 
@@ -42,7 +42,7 @@ def _has_compatible_delta(self, unit: str) -> bool:
             self._get_unit_definition(d).reference == offset_unit_dim for d in deltas
         )
 
-    def _ok_for_muldiv(self, no_offset_units: int | None = None) -> bool:
+    def _ok_for_muldiv(self, no_offset_units: Optional[int] = None) -> bool:
         """Checks if PlainQuantity object can be multiplied or divided"""
 
         is_ok = True