feature: Make CurrencyCollector generic over Currency (#40)

generate-currencies.py

@@ -14,7 +14,7 @@
 from .registry import CurrencyCollector
 from .registry import CurrencyRegistry
 
-__currencies: Final = CurrencyCollector()
+__currencies: Final = CurrencyCollector[Currency]()
 """
 currency_template = """
 
@@ -30,7 +30,7 @@ class {code}Type(Currency):
 registry_template = """\
 
 
-registry: Final[CurrencyRegistry] = __currencies.finalize()
+registry: Final[CurrencyRegistry[Currency]] = __currencies.finalize()
 del __currencies
 """
 

src/immoney/_base.py

@@ -118,7 +118,7 @@ def overdraft(
         return Overdraft(Money(value, self))
 
     @classmethod
-    def get_default_registry(cls) -> CurrencyRegistry:
+    def get_default_registry(cls) -> CurrencyRegistry[Currency]:
         from .currencies import registry
 
         return registry

src/immoney/_pydantic.py

@@ -19,6 +19,8 @@
 from .currencies import registry as default_registry
 from .registry import CurrencyRegistry
 
+C = TypeVar("C", bound=Currency)
+
 
 class MoneyDict(TypedDict):
     subunits: int
@@ -82,7 +84,9 @@ def schema(currency_schema: core_schema.CoreSchema) -> core_schema.CoreSchema:
 
     @staticmethod
     @abc.abstractmethod
-    def validator_from_registry(registry: CurrencyRegistry) -> GeneralValidatorFunction:
+    def validator_from_registry(
+        registry: CurrencyRegistry[Currency],
+    ) -> GeneralValidatorFunction:
         ...
 
     @staticmethod
@@ -118,11 +122,13 @@ def schema(currency_schema: core_schema.CoreSchema) -> core_schema.CoreSchema:
         )
 
     @staticmethod
-    def validator_from_registry(registry: CurrencyRegistry) -> GeneralValidatorFunction:
+    def validator_from_registry(
+        registry: CurrencyRegistry[C],
+    ) -> GeneralValidatorFunction:
         def validate_money(
             value: MoneyDict | Money[Currency],
             *args: object,
-            _registry: CurrencyRegistry = registry,
+            _registry: CurrencyRegistry[C] = registry,
         ) -> Money[Currency]:
             if isinstance(value, Money):
                 if value.currency.code not in _registry:
@@ -192,11 +198,13 @@ def schema(currency_schema: core_schema.CoreSchema) -> core_schema.CoreSchema:
         )
 
     @staticmethod
-    def validator_from_registry(registry: CurrencyRegistry) -> GeneralValidatorFunction:
+    def validator_from_registry(
+        registry: CurrencyRegistry[C],
+    ) -> GeneralValidatorFunction:
         def validate_subunit_fraction(
             value: SubunitFractionDict | SubunitFraction[Currency],
             *args: object,
-            _registry: CurrencyRegistry = registry,
+            _registry: CurrencyRegistry[C] = registry,
         ) -> SubunitFraction[Currency]:
             if isinstance(value, SubunitFraction):
                 if value.currency.code not in _registry:
@@ -258,11 +266,13 @@ def schema(currency_schema: core_schema.CoreSchema) -> core_schema.CoreSchema:
         )
 
     @staticmethod
-    def validator_from_registry(registry: CurrencyRegistry) -> GeneralValidatorFunction:
+    def validator_from_registry(
+        registry: CurrencyRegistry[C],
+    ) -> GeneralValidatorFunction:
         def validate_overdraft(
             value: OverdraftDict | Overdraft[Currency],
             *args: object,
-            _registry: CurrencyRegistry = registry,
+            _registry: CurrencyRegistry[C] = registry,
         ) -> Overdraft[Currency]:
             if isinstance(value, Overdraft):
                 if value.money.currency.code not in _registry:
@@ -336,9 +346,7 @@ def build_generic_currency_schema(
     )
 
 
-def build_currency_schema(
-    cls: type[Currency],
-) -> core_schema.CoreSchema:
+def build_currency_schema(cls: type[C]) -> core_schema.CoreSchema:
     if abc.ABC not in cls.__bases__:
         raise NotImplementedError(
             "Using concrete Currency types as Pydantic fields is not yet supported."
@@ -349,7 +357,7 @@ def build_currency_schema(
     def validate_currency(
         value: str,
         *args: object,
-        registry: CurrencyRegistry = cls_registry,
+        registry: CurrencyRegistry[Currency] = cls_registry,
     ) -> Currency:
         if isinstance(value, str):
             return registry[value]

src/immoney/currencies.py

@@ -7,7 +7,7 @@
 from .registry import CurrencyCollector
 from .registry import CurrencyRegistry
 
-__currencies: Final = CurrencyCollector()
+__currencies: Final = CurrencyCollector[Currency]()
 
 
 @final
@@ -3090,5 +3090,5 @@ class ZWNType(Currency):
 __currencies.add(ZWN)
 
 
-registry: Final[CurrencyRegistry] = __currencies.finalize()
+registry: Final[CurrencyRegistry[Currency]] = __currencies.finalize()
 del __currencies

src/immoney/registry.py

@@ -1,21 +1,24 @@
 from collections.abc import Mapping
+from typing import Generic
 from typing import TypeAlias
+from typing import TypeVar
 
 from immutables import Map
 
 from ._base import Currency
 
-CurrencyRegistry: TypeAlias = Mapping[str, Currency]
+C = TypeVar("C", bound=Currency)
+CurrencyRegistry: TypeAlias = Mapping[str, C]
 
 
-class CurrencyCollector:
+class CurrencyCollector(Generic[C]):
     __slots__ = ("__collection",)
 
     def __init__(self) -> None:
-        self.__collection = list[tuple[str, Currency]]()
+        self.__collection = list[tuple[str, C]]()
 
-    def add(self, currency: Currency) -> None:
+    def add(self, currency: C) -> None:
         self.__collection.append((currency.code, currency))
 
-    def finalize(self) -> CurrencyRegistry:
+    def finalize(self) -> CurrencyRegistry[C]:
         return Map(self.__collection)

tests/custom_currency.py

@@ -1,18 +1,22 @@
+from __future__ import annotations
+
 import abc
 from typing import Final
 
+from typing_extensions import assert_type
+
 from immoney import Currency
 from immoney.registry import CurrencyCollector
 from immoney.registry import CurrencyRegistry
 
 
 class CustomCurrency(Currency, abc.ABC):
     @classmethod
-    def get_default_registry(cls) -> CurrencyRegistry:
+    def get_default_registry(cls) -> CurrencyRegistry[CustomCurrency]:
         return registry
 
 
-__currencies: Final = CurrencyCollector()
+__currencies: Final = CurrencyCollector[CustomCurrency]()
 
 
 class JupiterCoinType(CustomCurrency):
@@ -34,4 +38,5 @@ class MoonCoinType(CustomCurrency):
 
 
 registry: Final = __currencies.finalize()
+assert_type(registry, CurrencyRegistry[CustomCurrency])
 del __currencies

tests/test_registry.py

@@ -7,7 +7,7 @@
 from immoney import currencies
 from immoney.registry import CurrencyCollector
 
-collector: Final = CurrencyCollector()
+collector: Final = CurrencyCollector[Currency]()
 
 
 @final