Merge pull request #3 from Azureblade3808/v0.1.3

V0.1.3

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "runtime-keypath"
-version = "0.1.2"
+version = "0.1.3"
 authors = [{ name = "Chris Fu", email = "[email protected]" }]
 description = "Supports runtime key-path recording/accessing for Python."
 classifiers = [

runtime_keypath/_core.py

@@ -26,7 +26,6 @@
 from typing import NamedTuple
 
 _Value_t = TypeVar("_Value_t")
-_Value_co = TypeVar("_Value_co", covariant=True)
 
 
 class _ThreadLocalProtocol(Protocol):
@@ -225,11 +224,11 @@ def __del__(self, /) -> None:
 
 
 @final
-class KeyPath(Generic[_Value_co], metaclass=_KeyPathMeta):
-    __target: Final[object]
+class KeyPath(Generic[_Value_t], metaclass=_KeyPathMeta):
+    __target: Final[Any]
     __keys: Final[Sequence[str]]
 
-    def __init__(self, /, target: object, keys: str | Sequence[str]) -> None:
+    def __init__(self, /, target: Any, keys: str | Sequence[str]) -> None:
         self.__target = target
 
         if isinstance(keys, str):
@@ -239,13 +238,27 @@ def __init__(self, /, target: object, keys: str | Sequence[str]) -> None:
         self.__keys = keys
 
     @property
-    def target(self, /) -> object:
+    def target(self, /) -> Any:
         return self.__target
 
     @property
     def keys(self, /) -> Sequence[str]:
         return self.__keys
 
+    def get(self, /) -> _Value_t:
+        value = self.__target
+        for key in self.__keys:
+            value = getattr(value, key)
+        return value
+
+    def set(self, value: _Value_t, /) -> None:
+        target = self.__target
+        keys = self.__keys
+        n = len(keys) - 1
+        for i in range(n):
+            target = getattr(target, keys[i])
+        setattr(target, keys[n], value)
+
     def __hash__(self, /) -> int:
         return hash((self.target, self.keys))
 
@@ -259,11 +272,8 @@ def __eq__(self, other: object, /) -> bool:
     def __repr__(self, /) -> str:
         return f"{KeyPath.__name__}(target={self.target!r}, keys={self.keys!r})"
 
-    def __call__(self, /) -> _Value_co:
-        value = self.__target
-        for key in self.__keys:
-            value = getattr(value, key)
-        return cast("_Value_co", value)
+    def __call__(self, /) -> _Value_t:
+        return self.get()
 
 
 class KeyPathSupporting:

runtime_keypath/_core_test.py

@@ -169,3 +169,36 @@ def v2(self) -> int:
 
     c = C()
     assert KeyPath.of(c.v0) == KeyPath(target=c, keys=("v0",))
+
+
+def test_get_set() -> None:
+    class A(KeyPathSupporting):
+        b: B | None = None
+
+    class B(KeyPathSupporting):
+        c: C | None = None
+
+    class C(KeyPathSupporting):
+        v: int | None = None
+
+    a = A()
+    b = B()
+    c = C()
+
+    key_path_0 = KeyPath.of(a.b)
+    assert key_path_0.get() is None
+    key_path_0.set(b)
+    assert a.b is b
+    assert key_path_0.get() is b
+
+    key_path_1 = KeyPath.of(a.b.c)  # type: ignore
+    assert key_path_1.get() is None
+    key_path_1.set(c)
+    assert a.b.c is c  # type: ignore
+    assert key_path_1.get() is c
+
+    key_path_2 = KeyPath.of(a.b.c.v)  # type: ignore
+    assert key_path_2.get() is None
+    key_path_2.set(12345)
+    assert a.b.c.v == 12345  # type: ignore
+    assert key_path_2.get() == 12345