Allow factories to have any amount of arguments (#110)

CHANGELOG.md

@@ -37,6 +37,10 @@ You can find our backwards-compatibility policy [here](https://github.com/hynek/
   [#72](https://github.com/hynek/svcs/issues/72)
   [#73](https://github.com/hynek/svcs/pull/73)
 
+- `Registry.register_factory()` is now more lenient regarding the arguments of the factory.
+  It only looks at the first argument (if present) and ignores the rest.
+  [#110](https://github.com/hynek/svcs/pull/110)
+
 
 ### Fixed
 

src/svcs/_core.py

@@ -279,6 +279,9 @@ def register_factory(
                 Can also be an async callable or an
                 :class:`collections.abc.Awaitable`; then
                 :meth:`svcs.Registry.aclose()` must be called.
+
+        .. versionchanged:: 24.2.0
+            *factory* now may take any amount of arguments and they are ignored.
         """
         rs = self._register_factory(
             svc_type,
@@ -454,14 +457,10 @@ def _takes_container(factory: Callable) -> bool:
         except Exception:  # noqa: BLE001
             return False
 
-    if not sig.parameters:
-        return False
-
-    if len(sig.parameters) != 1:
-        msg = "Factories must take 0 or 1 parameters."
-        raise TypeError(msg)
-
-    ((name, p),) = tuple(sig.parameters.items())
+    try:
+        (name, p) = next(iter(sig.parameters.items()))
+    except StopIteration:
+        return False  # 0 arguments
 
     return name == "svcs_container" or p.annotation in (
         Container,

tests/test_registry.py

@@ -432,17 +432,14 @@ def test_annotation_str(self, module_source, create_module):
 
         assert svcs._core._takes_container(module.factory)
 
-    def test_catches_invalid_sigs(self):
+    def test_ignores_invalid_sigs(self):
         """
-        If the factory takes more than one parameter, raise an TypeError.
+        If the first parameter is anything but what we handle, ignore it.
         """
 
         def factory(foo, bar): ...
 
-        with pytest.raises(
-            TypeError, match="Factories must take 0 or 1 parameters."
-        ):
-            svcs._core._takes_container(factory)
+        assert not svcs._core._takes_container(factory)
 
     def test_call_works(self):
         """