More typing (draft)

pint/_typing.py

@@ -63,3 +63,7 @@ def __setitem__(self, key: Any, value: Any) -> None:
 
 FuncType = Callable[..., Any]
 F = TypeVar("F", bound=FuncType)
+
+
+# TODO: Improve or delete types
+QuantityArgument = Any

pint/facets/context/objects.py

@@ -10,12 +10,20 @@
 
 import weakref
 from collections import ChainMap, defaultdict
-from typing import Any
+from typing import Any, Callable
 from collections.abc import Iterable
 
 from ...facets.plain import UnitDefinition
 from ...util import UnitsContainer, to_units_container
 from .definitions import ContextDefinition
+from ..._typing import Magnitude
+
+Transformation = Callable[
+    [
+        Magnitude,
+    ],
+    Magnitude,
+]
 
 
 class Context:
@@ -75,14 +83,14 @@ def __init__(
         aliases: tuple[str] = tuple(),
         defaults: dict[str, Any] | None = None,
     ) -> None:
-        self.name = name
-        self.aliases = aliases
+        self.name: str | None = name
+        self.aliases: tuple[str] = aliases
 
         #: Maps (src, dst) -> transformation function
-        self.funcs = {}
+        self.funcs: dict[tuple[UnitsContainer, UnitsContainer], Transformation] = {}
 
         #: Maps defaults variable names to values
-        self.defaults = defaults or {}
+        self.defaults: dict[str, Any] = defaults or {}
 
         # Store Definition objects that are context-specific
         self.redefinitions = []
@@ -154,7 +162,9 @@ def from_definition(cls, cd: ContextDefinition, to_base_func=None) -> Context:
 
         return ctx
 
-    def add_transformation(self, src, dst, func) -> None:
+    def add_transformation(
+        self, src: UnitsContainer, dst: UnitsContainer, func: Transformation
+    ) -> None:
         """Add a transformation function to the context."""
 
         _key = self.__keytransform__(src, dst)
@@ -202,7 +212,7 @@ def _redefine(self, definition: UnitDefinition):
 
     def hashable(
         self,
-    ) -> tuple[str | None, tuple[str, ...], frozenset, frozenset, tuple]:
+    ) -> tuple[str | None, tuple[str], frozenset, frozenset, tuple]:
         """Generate a unique hashable and comparable representation of self, which can
         be used as a key in a dict. This class cannot define ``__hash__`` because it is
         mutable, and the Python interpreter does cache the output of ``__hash__``.

pint/facets/group/objects.py

@@ -8,10 +8,28 @@
 
 from __future__ import annotations
 
+from typing import Callable, Any, TYPE_CHECKING
+
 from collections.abc import Generator, Iterable
 from ...util import SharedRegistryObject, getattr_maybe_raise
 from .definitions import GroupDefinition
 
+if TYPE_CHECKING:
+    from ..plain import UnitDefinition
+
+    DefineFunc = Callable[
+        [
+            Any,
+        ],
+        None,
+    ]
+    AddUnitFunc = Callable[
+        [
+            UnitDefinition,
+        ],
+        None,
+    ]
+
 
 class Group(SharedRegistryObject):
     """A group is a set of units.
@@ -57,7 +75,7 @@ def __init__(self, name: str):
         self._computed_members: frozenset[str] | None = None
 
     @property
-    def members(self):
+    def members(self) -> frozenset[str]:
         """Names of the units that are members of the group.
 
         Calculated to include to all units in all included _used_groups.
@@ -143,7 +161,7 @@ def remove_groups(self, *group_names: str) -> None:
 
     @classmethod
     def from_lines(
-        cls, lines: Iterable[str], define_func, non_int_type: type = float
+        cls, lines: Iterable[str], define_func: DefineFunc, non_int_type: type = float
     ) -> Group:
         """Return a Group object parsing an iterable of lines.
 
@@ -160,11 +178,15 @@ def from_lines(
 
         """
         group_definition = GroupDefinition.from_lines(lines, non_int_type)
+
+        if group_definition is None:
+            raise ValueError(f"Could not define group from {lines}")
+
         return cls.from_definition(group_definition, define_func)
 
     @classmethod
     def from_definition(
-        cls, group_definition: GroupDefinition, add_unit_func=None
+        cls, group_definition: GroupDefinition, add_unit_func: AddUnitFunc | None = None
     ) -> Group:
         grp = cls(group_definition.name)
 

pint/facets/plain/registry.py

@@ -20,6 +20,8 @@
 from fractions import Fraction
 from numbers import Number
 from token import NAME, NUMBER
+from tokenize import TokenInfo
+
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -33,7 +35,7 @@
     from ..context import Context
     from ..._typing import Quantity, Unit
 
-from ..._typing import QuantityOrUnitLike, UnitLike
+from ..._typing import QuantityOrUnitLike, UnitLike, QuantityArgument
 from ..._vendor import appdirs
 from ...compat import HAS_BABEL, babel_parse, tokenizer
 from ...errors import DimensionalityError, RedefinitionError, UndefinedUnitError
@@ -75,8 +77,10 @@
 
 
 @functools.lru_cache
-def pattern_to_regex(pattern):
-    if hasattr(pattern, "finditer"):
+def pattern_to_regex(pattern: str | re.Pattern[str]) -> re.Pattern[str]:
+    # TODO: This has been changed during typing improvements.
+    # if hasattr(pattern, "finditer"):
+    if not isinstance(pattern, str):
         pattern = pattern.pattern
 
     # Replace "{unit_name}" match string with float regex with unit_name as group
@@ -197,7 +201,15 @@ def __init__(
         mpl_formatter: str = "{:P}",
     ):
         #: Map a definition class to a adder methods.
-        self._adders = {}
+        self._adders: dict[
+            type[T],
+            Callable[
+                [
+                    T,
+                ],
+                None,
+            ],
+        ] = {}
         self._register_definition_adders()
         self._init_dynamic_classes()
 
@@ -297,7 +309,16 @@ def _after_init(self) -> None:
         self._build_cache(loaded_files)
         self._initialized = True
 
-    def _register_adder(self, definition_class, adder_func):
+    def _register_adder(
+        self,
+        definition_class: type[T],
+        adder_func: Callable[
+            [
+                T,
+            ],
+            None,
+        ],
+    ) -> None:
         """Register a block definition."""
         self._adders[definition_class] = adder_func
 
@@ -316,18 +337,18 @@ def __deepcopy__(self, memo) -> PlainRegistry:
         new._init_dynamic_classes()
         return new
 
-    def __getattr__(self, item):
+    def __getattr__(self, item: str) -> Unit:
         getattr_maybe_raise(self, item)
         return self.Unit(item)
 
-    def __getitem__(self, item):
+    def __getitem__(self, item: str):
         logger.warning(
             "Calling the getitem method from a UnitRegistry is deprecated. "
             "use `parse_expression` method or use the registry as a callable."
         )
         return self.parse_expression(item)
 
-    def __contains__(self, item) -> bool:
+    def __contains__(self, item: str) -> bool:
         """Support checking prefixed units with the `in` operator"""
         try:
             self.__getattr__(item)
@@ -390,7 +411,7 @@ def cache_folder(self) -> pathlib.Path | None:
     def non_int_type(self):
         return self._non_int_type
 
-    def define(self, definition):
+    def define(self, definition: str | type) -> None:
         """Add unit to the registry.
 
         Parameters
@@ -413,7 +434,7 @@ def define(self, definition):
     # - then we define specific adder for each definition class. :-D
     ############
 
-    def _helper_dispatch_adder(self, definition):
+    def _helper_dispatch_adder(self, definition: Any) -> None:
         """Helper function to add a single definition,
         choosing the appropiate method by class.
         """
@@ -474,19 +495,19 @@ def _add_alias(self, definition: AliasDefinition):
         for alias in definition.aliases:
             self._helper_single_adder(alias, unit, self._units, self._units_casei)
 
-    def _add_dimension(self, definition: DimensionDefinition):
+    def _add_dimension(self, definition: DimensionDefinition) -> None:
         self._helper_adder(definition, self._dimensions, None)
 
-    def _add_derived_dimension(self, definition: DerivedDimensionDefinition):
+    def _add_derived_dimension(self, definition: DerivedDimensionDefinition) -> None:
         for dim_name in definition.reference.keys():
             if dim_name not in self._dimensions:
                 self._add_dimension(DimensionDefinition(dim_name))
         self._helper_adder(definition, self._dimensions, None)
 
-    def _add_prefix(self, definition: PrefixDefinition):
+    def _add_prefix(self, definition: PrefixDefinition) -> None:
         self._helper_adder(definition, self._prefixes, None)
 
-    def _add_unit(self, definition: UnitDefinition):
+    def _add_unit(self, definition: UnitDefinition) -> None:
         if definition.is_base:
             self._base_units.append(definition.name)
             for dim_name in definition.reference.keys():
@@ -673,7 +694,7 @@ def _get_dimensionality_recurse(self, ref, exp, accumulator):
                 if reg.reference is not None:
                     self._get_dimensionality_recurse(reg.reference, exp2, accumulator)
 
-    def _get_dimensionality_ratio(self, unit1, unit2):
+    def _get_dimensionality_ratio(self, unit1: UnitLike, unit2: UnitLike):
         """Get the exponential ratio between two units, i.e. solve unit2 = unit1**x for x.
 
         Parameters
@@ -780,7 +801,9 @@ def _get_root_units(self, input_units, check_nonmult=True):
         cache[input_units] = factor, units
         return factor, units
 
-    def get_base_units(self, input_units, check_nonmult=True, system=None):
+    def get_base_units(
+        self, input_units: UnitsContainer | str, check_nonmult: bool = True, system=None
+    ):
         """Convert unit or dict of units to the plain units.
 
         If any unit is non multiplicative and check_converter is True,
@@ -1104,7 +1127,32 @@ def _parse_units(
 
         return ret
 
-    def _eval_token(self, token, case_sensitive=None, **values):
+    def _eval_token(
+        self,
+        token: TokenInfo,
+        case_sensitive: bool | None = None,
+        **values: QuantityArgument,
+    ):
+        """Evaluate a single token using the following rules:
+
+        1. numerical values as strings are replaced by their numeric counterparts
+            - integers are parsed as integers
+            - other numeric values are parses of non_int_type
+        2. strings in (inf, infinity, nan, dimensionless) with their numerical value.
+        3. strings in values.keys() are replaced by Quantity(values[key])
+        4. in other cases, the values are parsed as units and replaced by their canonical name.
+
+        Parameters
+        ----------
+        token
+            Token to evaluate.
+        case_sensitive, optional
+            If true, a case sensitive matching of the unit name will be done in the registry.
+            If false, a case INsensitive matching of the unit name will be done in the registry.
+            (Default value = None, which uses registry setting)
+        **values
+            Other string that will be parsed using the Quantity constructor on their corresponding value.
+        """
         token_type = token[0]
         token_text = token[1]
         if token_type == NAME:
@@ -1139,28 +1187,25 @@ def parse_pattern(
 
         Parameters
         ----------
-        input_string :
+        input_string
 
         pattern_string:
-             The regex parse string
-        case_sensitive :
-             (Default value = None, which uses registry setting)
-        many :
+            The regex parse string
+        case_sensitive, optional
+            If true, a case sensitive matching of the unit name will be done in the registry.
+            If false, a case INsensitive matching of the unit name will be done in the registry.
+            (Default value = None, which uses registry setting)
+        many, optional
              Match many results
              (Default value = False)
-
-
-        Returns
-        -------
-
         """
 
         if not input_string:
             return [] if many else None
 
         # Parse string
-        pattern = pattern_to_regex(pattern)
-        matched = re.finditer(pattern, input_string)
+        regex = pattern_to_regex(pattern)
+        matched = re.finditer(regex, input_string)
 
         # Extract result(s)
         results = []
@@ -1196,16 +1241,14 @@ def parse_expression(
 
         Parameters
         ----------
-        input_string :
-
-        case_sensitive :
-             (Default value = None, which uses registry setting)
-        **values :
-
-
-        Returns
-        -------
-
+        input_string
+
+        case_sensitive, optional
+            If true, a case sensitive matching of the unit name will be done in the registry.
+            If false, a case INsensitive matching of the unit name will be done in the registry.
+            (Default value = None, which uses registry setting)
+        **values
+            Other string that will be parsed using the Quantity constructor on their corresponding value.
         """
         if not input_string:
             return self.Quantity(1)
@@ -1215,8 +1258,9 @@ def parse_expression(
         input_string = string_preprocessor(input_string)
         gen = tokenizer(input_string)
 
-        return build_eval_tree(gen).evaluate(
-            lambda x: self._eval_token(x, case_sensitive=case_sensitive, **values)
-        )
+        def _define_op(s: str):
+            return self._eval_token(s, case_sensitive=case_sensitive, **values)
+
+        return build_eval_tree(gen).evaluate(_define_op)
 
     __call__ = parse_expression