Support wiring of Cython-compiled modules

.gitignore

@@ -70,6 +70,11 @@ src/**/*.h
 src/**/*.so
 src/**/*.html
 
+# Cython test fixture build outputs
+tests/unit/samples/wiringcython/*.c
+tests/unit/samples/wiringcython/*.so
+tests/unit/samples/wiringcython/_build/
+
 # Workspace for samples
 .workspace/
 

docs/wiring.rst

@@ -658,6 +658,57 @@ or with a single container ``register_loader_containers(container)`` multiple ti
 To unregister a container use ``unregister_loader_containers(container)``.
 Wiring module will uninstall the import hook when unregister last container.
 
+Wiring of Cython-compiled modules
+---------------------------------
+
+Modules compiled with Cython (e.g. to ship business logic as ``.so``
+extensions in source-protected container images) are wired transparently
+provided the compile sets two directives:
+
+* ``binding=True`` — preserve descriptor / bound-method semantics so
+  :func:`inspect.signature` and the wiring discovery pass work as they do
+  for pure-Python functions.
+* ``embedsignature=True`` — embed the Python-style signature so
+  :func:`inspect.signature` can recover parameter names, annotations, and
+  ``Provide[...]`` / ``Provider[...]`` markers from the compiled function.
+
+A typical ``cythonize`` invocation that produces wiring-compatible
+extensions for a FastAPI / dependency-injector codebase:
+
+.. code-block:: python
+
+   from Cython.Build import cythonize
+
+   cythonize(
+       ["my_package/handlers/*.py"],
+       compiler_directives={
+           "language_level": 3,
+           "binding": True,
+           "embedsignature": True,
+       },
+   )
+
+FastAPI views and dependencies that rely on parameter defaults as
+markers (``param: str = Header(...)``, ``svc: Service = Depends(...)``,
+``Provide[Container.x]``) need Cython's C-level annotation typing
+disabled. The default in Cython 3.x is ``annotation_typing=True``, which
+generates ``isinstance`` checks against the annotated types and rejects
+the marker objects at call time. Opt out per-function:
+
+.. code-block:: python
+
+   import cython
+
+   @cython.annotation_typing(False)
+   async def list_users(
+       svc: UserService = Depends(Provide[Container.user_service]),
+   ) -> list[User]:
+       return await svc.list()
+
+Apply the decorator to every FastAPI view or dependency callable that
+takes a marker-style default. Module-level ``annotation_typing=False``
+works too if the whole module is FastAPI-bound.
+
 Few notes on performance
 ------------------------
 

src/dependency_injector/wiring.py

@@ -127,6 +127,17 @@ def is_werkzeug_local_proxy(obj: Any) -> bool:
 
     INSPECT_EXCLUSION_FILTERS.append(is_werkzeug_local_proxy)
 
+
+def _is_cyfunction(obj: Any) -> bool:
+    """Return True for Cython-compiled functions/methods (non-fused)."""
+    return type(obj).__name__ == "cython_function_or_method"
+
+
+def _is_function_like(obj: Any) -> bool:
+    """Return True for pure-Python functions and Cython-compiled functions."""
+    return isfunction(obj) or _is_cyfunction(obj)
+
+
 from . import providers  # noqa: E402
 
 __all__ = (
@@ -485,7 +496,7 @@ def wire(  # noqa: C901
                     warn_unresolved=warn_unresolved,
                     warn_unresolved_stacklevel=1,
                 )
-            elif isfunction(member):
+            elif _is_function_like(member):
                 _patch_fn(
                     module,
                     member_name,
@@ -548,10 +559,10 @@ def unwire(  # noqa: C901
 
     for module in modules:
         for name, member in getmembers(module):
-            if isfunction(member):
+            if _is_function_like(member):
                 _unpatch(module, name, member)
             elif isclass(member):
-                for method_name, method in getmembers(member, isfunction):
+                for method_name, method in getmembers(member, _is_function_like):
                     _unpatch(member, method_name, method)
 
         for patched in _patched_registry.get_callables_from_module(module):
@@ -803,7 +814,7 @@ def _fetch_modules(package):
 
 
 def _is_method(member) -> bool:
-    return ismethod(member) or isfunction(member)
+    return ismethod(member) or _is_function_like(member)
 
 
 def _is_marker(member) -> bool:

tests/unit/samples/wiringcython/container.py

@@ -0,0 +1,20 @@
+"""DI container used by the Cython-compiled wiring fixture."""
+
+from dependency_injector import containers, providers
+
+
+class Service:
+    """Simple service injected into the Cython-compiled fixture handlers."""
+
+    def __init__(self, value: str = "default") -> None:
+        self.value = value
+
+    async def aget(self) -> str:
+        return self.value
+
+    def get(self) -> str:
+        return self.value
+
+
+class Container(containers.DeclarativeContainer):
+    service = providers.Factory(Service, value="injected")

tests/unit/samples/wiringcython/cythonmodule.pyx

@@ -0,0 +1,23 @@
+# cython: language_level=3, binding=True, embedsignature=True, annotation_typing=False
+
+from dependency_injector.wiring import Provide
+
+from samples.wiringcython.container import Container, Service
+
+
+def sync_handler(svc: Service = Provide[Container.service]) -> str:
+    return svc.get()
+
+
+async def async_handler(svc: Service = Provide[Container.service]) -> str:
+    return await svc.aget()
+
+
+async def async_gen_handler(svc: Service = Provide[Container.service]):
+    yield svc.get()
+    yield svc.get() + "_2"
+
+
+class HandlerClass:
+    async def __call__(self, svc: Service = Provide[Container.service]) -> str:
+        return svc.get()

tests/unit/wiring/test_cython.py

@@ -0,0 +1,102 @@
+"""Wiring discovery against Cython-compiled user modules."""
+
+import pytest
+
+pytest.importorskip("Cython")
+
+import pyximport  # noqa: E402
+
+pyximport.install(language_level=3)
+
+cythonmodule = pytest.importorskip(
+    "samples.wiringcython.cythonmodule",
+    reason="Cython fixture not built (Cython / C toolchain missing)",
+)
+
+from samples.wiringcython.container import Container, Service  # noqa: E402
+
+from dependency_injector import providers  # noqa: E402
+from dependency_injector.wiring import (  # noqa: E402
+    _is_cyfunction,
+    _is_function_like,
+    _patched_registry,
+)
+
+
+@pytest.fixture
+def container():
+    c = Container()
+    c.wire(modules=[cythonmodule])
+    yield c
+    c.unwire()
+
+
+def _pure_python_fn():
+    pass
+
+
+@pytest.mark.parametrize(
+    "obj,is_cy,is_func_like",
+    [
+        pytest.param(lambda: cythonmodule.sync_handler, True, True, id="cython-sync"),
+        pytest.param(lambda: cythonmodule.async_handler, True, True, id="cython-async"),
+        pytest.param(
+            lambda: cythonmodule.async_gen_handler, True, True, id="cython-async-gen"
+        ),
+        pytest.param(
+            lambda: cythonmodule.HandlerClass.__call__,
+            True,
+            True,
+            id="cython-class-call",
+        ),
+        pytest.param(lambda: _pure_python_fn, False, True, id="pure-python"),
+    ],
+)
+def test_function_like_predicate(obj, is_cy, is_func_like):
+    target = obj()
+    assert _is_cyfunction(target) is is_cy
+    assert _is_function_like(target) is is_func_like
+
+
+def test_sync_handler_wired(container):
+    assert cythonmodule.sync_handler() == "injected"
+
+
+@pytest.mark.asyncio
+async def test_async_handler_wired(container):
+    assert await cythonmodule.async_handler() == "injected"
+
+
+@pytest.mark.asyncio
+async def test_async_gen_handler_wired(container):
+    results = [v async for v in cythonmodule.async_gen_handler()]
+    assert results == ["injected", "injected_2"]
+
+
+@pytest.mark.asyncio
+async def test_class_method_wired(container):
+    handler = cythonmodule.HandlerClass()
+    assert await handler() == "injected"
+
+
+def test_sync_handler_respects_provider_override(container):
+    with container.service.override(providers.Object(Service(value="overridden"))):
+        assert cythonmodule.sync_handler() == "overridden"
+    assert cythonmodule.sync_handler() == "injected"
+
+
+def test_unwire_clears_injection_bindings_on_compiled_module():
+    c = Container()
+    c.wire(modules=[cythonmodule])
+
+    wrapper = cythonmodule.sync_handler
+    patched = _patched_registry.get_callable(wrapper)
+
+    assert patched is not None
+    assert patched.reference_injections
+    assert patched.injections
+
+    c.unwire()
+
+    assert patched.injections == {}
+    assert patched.reference_injections

tox.ini

@@ -18,6 +18,8 @@ deps=
     pydantic-settings
     werkzeug
     fast-depends
+    # Cython is required to build tests/unit/samples/wiringcython/
+    cython>=3,<4
 extras=
     yaml
 commands = pytest