fix: generic type handling

Author: buiapp

src/reaktiv/model.py

@@ -178,8 +178,24 @@ def destroy(self) -> None: ...
 class SignalField(Generic[T]):
     """Descriptor that creates one writable Signal per model instance."""
 
-    def __init__(self, initial_value: Callable[[], T]) -> None:
-        self._initial_value = initial_value
+    @overload
+    def __init__(self, default: T, /) -> None: ...
+
+    @overload
+    def __init__(self, *, factory: Callable[[], T]) -> None: ...
+
+    def __init__(
+        self,
+        *defaults: T,
+        factory: Optional[Callable[[], T]] = None,
+    ) -> None:
+        if len(defaults) == 1 and factory is None:
+            default = defaults[0]
+            self._initial_value = lambda: default
+        elif not defaults and factory is not None:
+            self._initial_value = factory
+        else:
+            raise TypeError("field() requires exactly one default value or a factory")
         self._cache: WeakKeyDictionary[object, Signal[T]] = WeakKeyDictionary()
         self._storage_name: Optional[str] = None
 
@@ -257,54 +273,4 @@ def _set_on_instance_dict(self, instance: object, value: Signal[T]) -> None:
         vars(instance)[self._storage_name] = value
 
 
-class _TypedFieldFactory(Generic[T]):
-    """Typed field factory used by `field[T]` syntax."""
-
-    @overload
-    def __call__(self, default: T, /) -> SignalField[T]: ...
-
-    @overload
-    def __call__(self, *, factory: Callable[[], T]) -> SignalField[T]: ...
-
-    def __call__(
-        self,
-        *defaults: T,
-        factory: Optional[Callable[[], T]] = None,
-    ) -> SignalField[T]:
-        return _create_field(defaults, factory)
-
-
-class _FieldFactory:
-    """Declare a per-instance Signal field on a ReactiveModel."""
-
-    @overload
-    def __call__(self, default: T, /) -> SignalField[T]: ...
-
-    @overload
-    def __call__(self, *, factory: Callable[[], T]) -> SignalField[T]: ...
-
-    def __call__(
-        self,
-        *defaults: T,
-        factory: Optional[Callable[[], T]] = None,
-    ) -> SignalField[T]:
-        return _create_field(defaults, factory)
-
-    def __getitem__(self, value_type: type[T]) -> _TypedFieldFactory[T]:
-        del value_type
-        return _TypedFieldFactory()
-
-
-field = _FieldFactory()
-
-
-def _create_field(
-    defaults: tuple[T, ...],
-    factory: Optional[Callable[[], T]],
-) -> SignalField[T]:
-    if len(defaults) == 1 and factory is None:
-        default = defaults[0]
-        return SignalField(lambda: default)
-    if not defaults and factory is not None:
-        return SignalField(factory)
-    raise TypeError("field() requires exactly one default value or a factory")
+field = SignalField

tests/test_reactive_model.py

@@ -1,6 +1,7 @@
 import asyncio
 import gc
 import weakref
+from typing import Optional
 
 import pytest
 
@@ -58,6 +59,7 @@ class Profile(ReactiveModel):
         name = field[str]("")
         age = field[int](0)
         tags = field[list[str]](factory=list)
+        nickname = field[Optional[str]](None)
 
         def __init__(self, name: str, age: int = 0) -> None:
             self.observed: list[tuple[str, int]] = []
@@ -72,6 +74,7 @@ def observe(self) -> None:
     assert profile.name() == "Ada"
     assert profile.age() == 37
     assert profile.tags() == []
+    assert profile.nickname() is None
     assert profile.observed == [("Ada", 37)]
 
 

tests/typing/public_api_inference.py

@@ -6,6 +6,8 @@
 
 from __future__ import annotations
 
+from typing import Optional
+
 from reaktiv import (
     Computed,
     ComputeSignal,
@@ -66,6 +68,7 @@ class CounterModel(ReactiveModel):
     count = field(1)
     name = field[str]("")
     labels = field[list[str]](factory=list)
+    optional_name = field[Optional[str]](None)
 
     @computed
     def doubled(self) -> int:
@@ -132,6 +135,7 @@ async def load_cached_user(
 model_count: Signal[int] = model.count
 model_name_field: Signal[str] = model.name
 model_labels: Signal[list[str]] = model.labels
+model_optional_name: Signal[Optional[str]] = model.optional_name
 model_doubled: ComputeSignal[int] = model.doubled
 model_normalized_name: ComputeSignal[str] = model.normalized_name
 model_normalized_name_value: str = model.normalized_name()