Wiring: attribute injections (#414)

* Add implementation

* Add tests for module and class

* Add tests for module and class for string ids

* Update tests with typing

* Add tests for invalid type of marker

* Add docs and the example

* Update changelog

* Fix Python 3.6 tests and flake8

docs/main/changelog.rst

@@ -7,6 +7,13 @@ that were made in every particular version.
 From version 0.7.6 *Dependency Injector* framework strictly 
 follows `Semantic versioning`_
 
+Development version
+-------------------
+- Add wiring injections into modules and class attributes.
+  See issue: `#411 <https://github.com/ets-labs/python-dependency-injector/issues/411>`_.
+  Many thanks to `@brunopereira27 <https://github.com/brunopereira27>`_ for submitting
+  the use case.
+
 4.27.0
 ------
 - Introduce wiring inspect filter to filter out ``flask.request`` and other local proxy objects

docs/wiring.rst

@@ -164,6 +164,29 @@ To inject a container use special identifier ``<container>``:
    def foo(container: Container = Provide['<container>']) -> None:
        ...
 
+
+Making injections into modules and class attributes
+---------------------------------------------------
+
+You can use wiring to make injections into modules and class attributes.
+
+.. literalinclude:: ../examples/wiring/example_attribute.py
+   :language: python
+   :lines: 3-
+   :emphasize-lines: 16,21
+
+You could also use string identifiers to avoid a dependency on a container:
+
+.. code-block:: python
+   :emphasize-lines: 1,6
+
+   service: Service = Provide['service']
+
+
+   class Main:
+
+       service: Service = Provide['service']
+
 Wiring with modules and packages
 --------------------------------
 

examples/wiring/example_attribute.py

@@ -0,0 +1,31 @@
+"""Wiring attribute example."""
+
+import sys
+
+from dependency_injector import containers, providers
+from dependency_injector.wiring import Provide
+
+
+class Service:
+    ...
+
+
+class Container(containers.DeclarativeContainer):
+
+    service = providers.Factory(Service)
+
+
+service: Service = Provide[Container.service]
+
+
+class Main:
+
+    service: Service = Provide[Container.service]
+
+
+if __name__ == '__main__':
+    container = Container()
+    container.wire(modules=[sys.modules[__name__]])
+
+    assert isinstance(service, Service)
+    assert isinstance(Main.service, Service)

src/dependency_injector/wiring.py

@@ -20,6 +20,7 @@ from typing import (
     TypeVar,
     Type,
     Union,
+    Set,
     cast,
 )
 
@@ -82,22 +83,53 @@ F = TypeVar('F', bound=Callable[..., Any])
 Container = Any
 
 
-class Registry:
+class PatchedRegistry:
 
     def __init__(self):
-        self._storage = set()
+        self._callables: Set[Callable[..., Any]] = set()
+        self._attributes: Set[PatchedAttribute] = set()
 
-    def add(self, patched: Callable[..., Any]) -> None:
-        self._storage.add(patched)
+    def add_callable(self, patched: Callable[..., Any]) -> None:
+        self._callables.add(patched)
 
-    def get_from_module(self, module: ModuleType) -> Iterator[Callable[..., Any]]:
-        for patched in self._storage:
+    def get_callables_from_module(self, module: ModuleType) -> Iterator[Callable[..., Any]]:
+        for patched in self._callables:
             if patched.__module__ != module.__name__:
                 continue
             yield patched
 
+    def add_attribute(self, patched: 'PatchedAttribute'):
+        self._attributes.add(patched)
 
-_patched_registry = Registry()
+    def get_attributes_from_module(self, module: ModuleType) -> Iterator['PatchedAttribute']:
+        for attribute in self._attributes:
+            if not attribute.is_in_module(module):
+                continue
+            yield attribute
+
+    def clear_module_attributes(self, module: ModuleType):
+        for attribute in self._attributes.copy():
+            if not attribute.is_in_module(module):
+                continue
+            self._attributes.remove(attribute)
+
+
+class PatchedAttribute:
+
+    def __init__(self, member: Any, name: str, marker: '_Marker'):
+        self.member = member
+        self.name = name
+        self.marker = marker
+
+    @property
+    def module_name(self) -> str:
+        if isinstance(self.member, ModuleType):
+            return self.member.__name__
+        else:
+            return self.member.__module__
+
+    def is_in_module(self, module: ModuleType) -> bool:
+        return self.module_name == module.__name__
 
 
 class ProvidersMap:
@@ -278,9 +310,6 @@ class InspectFilter:
                and issubclass(instance, starlette.requests.Request)
 
 
-inspect_filter = InspectFilter()
-
-
 def wire(  # noqa: C901
         container: Container,
         *,
@@ -301,20 +330,27 @@ def wire(  # noqa: C901
     providers_map = ProvidersMap(container)
 
     for module in modules:
-        for name, member in inspect.getmembers(module):
-            if inspect_filter.is_excluded(member):
+        for member_name, member in inspect.getmembers(module):
+            if _inspect_filter.is_excluded(member):
                 continue
-            if inspect.isfunction(member):
-                _patch_fn(module, name, member, providers_map)
-            elif inspect.isclass(member):
-                for method_name, method in inspect.getmembers(member, _is_method):
-                    _patch_method(member, method_name, method, providers_map)
 
-        for patched in _patched_registry.get_from_module(module):
+            if _is_marker(member):
+                _patch_attribute(module, member_name, member, providers_map)
+            elif inspect.isfunction(member):
+                _patch_fn(module, member_name, member, providers_map)
+            elif inspect.isclass(member):
+                cls = member
+                for cls_member_name, cls_member in inspect.getmembers(cls):
+                    if _is_marker(cls_member):
+                        _patch_attribute(cls, cls_member_name, cls_member, providers_map)
+                    elif _is_method(cls_member):
+                        _patch_method(cls, cls_member_name, cls_member, providers_map)
+
+        for patched in _patched_registry.get_callables_from_module(module):
             _bind_injections(patched, providers_map)
 
 
-def unwire(
+def unwire(  # noqa: C901
         *,
         modules: Optional[Iterable[ModuleType]] = None,
         packages: Optional[Iterable[ModuleType]] = None,
@@ -335,15 +371,19 @@ def unwire(
                 for method_name, method in inspect.getmembers(member, inspect.isfunction):
                     _unpatch(member, method_name, method)
 
-        for patched in _patched_registry.get_from_module(module):
+        for patched in _patched_registry.get_callables_from_module(module):
             _unbind_injections(patched)
 
+        for patched_attribute in _patched_registry.get_attributes_from_module(module):
+            _unpatch_attribute(patched_attribute)
+        _patched_registry.clear_module_attributes(module)
+
 
 def inject(fn: F) -> F:
     """Decorate callable with injecting decorator."""
     reference_injections, reference_closing = _fetch_reference_injections(fn)
     patched = _get_patched(fn, reference_injections, reference_closing)
-    _patched_registry.add(patched)
+    _patched_registry.add_callable(patched)
     return cast(F, patched)
 
 
@@ -358,7 +398,7 @@ def _patch_fn(
         if not reference_injections:
             return
         fn = _get_patched(fn, reference_injections, reference_closing)
-        _patched_registry.add(fn)
+        _patched_registry.add_callable(fn)
 
     _bind_injections(fn, providers_map)
 
@@ -384,7 +424,7 @@ def _patch_method(
         if not reference_injections:
             return
         fn = _get_patched(fn, reference_injections, reference_closing)
-        _patched_registry.add(fn)
+        _patched_registry.add_callable(fn)
 
     _bind_injections(fn, providers_map)
 
@@ -411,6 +451,31 @@ def _unpatch(
     _unbind_injections(fn)
 
 
+def _patch_attribute(
+        member: Any,
+        name: str,
+        marker: '_Marker',
+        providers_map: ProvidersMap,
+) -> None:
+    provider = providers_map.resolve_provider(marker.provider, marker.modifier)
+    if provider is None:
+        return
+
+    _patched_registry.add_attribute(PatchedAttribute(member, name, marker))
+
+    if isinstance(marker, Provide):
+        instance = provider()
+        setattr(member, name, instance)
+    elif isinstance(marker, Provider):
+        setattr(member, name, provider)
+    else:
+        raise Exception(f'Unknown type of marker {marker}')
+
+
+def _unpatch_attribute(patched: PatchedAttribute) -> None:
+    setattr(patched.member, patched.name, patched.marker)
+
+
 def _fetch_reference_injections(
         fn: Callable[..., Any],
 ) -> Tuple[Dict[str, Any], Dict[str, Any]]:
@@ -484,6 +549,10 @@ def _is_method(member):
     return inspect.ismethod(member) or inspect.isfunction(member)
 
 
+def _is_marker(member):
+    return isinstance(member, _Marker)
+
+
 def _get_patched(fn, reference_injections, reference_closing):
     if inspect.iscoroutinefunction(fn):
         patched = _get_async_patched(fn)
@@ -825,9 +894,6 @@ class AutoLoader:
         importlib.invalidate_caches()
 
 
-_loader = AutoLoader()
-
-
 def register_loader_containers(*containers: Container) -> None:
     """Register containers in auto-wiring module loader."""
     _loader.register_containers(*containers)
@@ -851,3 +917,8 @@ def uninstall_loader() -> None:
 def is_loader_installed() -> bool:
     """Check if auto-wiring module loader hook is installed."""
     return _loader.installed
+
+
+_patched_registry = PatchedRegistry()
+_inspect_filter = InspectFilter()
+_loader = AutoLoader()

tests/unit/samples/wiringsamples/module.py

@@ -3,14 +3,24 @@
 from decimal import Decimal
 from typing import Callable
 
+from dependency_injector import providers
 from dependency_injector.wiring import inject, Provide, Provider
 
 from .container import Container, SubContainer
 from .service import Service
 
 
+service: Service = Provide[Container.service]
+service_provider: Callable[..., Service] = Provider[Container.service]
+undefined: Callable = Provide[providers.Provider()]
+
+
 class TestClass:
 
+    service: Service = Provide[Container.service]
+    service_provider: Callable[..., Service] = Provider[Container.service]
+    undefined: Callable = Provide[providers.Provider()]
+
     @inject
     def __init__(self, service: Service = Provide[Container.service]):
         self.service = service

tests/unit/samples/wiringsamples/module_invalid_attr_injection.py

@@ -0,0 +1,8 @@
+"""Test module for wiring with invalid type of marker for attribute injection."""
+
+from dependency_injector.wiring import Closing
+
+from .container import Container
+
+
+service = Closing[Container.service]

tests/unit/samples/wiringstringidssamples/module.py

@@ -19,8 +19,17 @@ from .container import Container
 from .service import Service
 
 
+service: Service = Provide['service']
+service_provider: Callable[..., Service] = Provider['service']
+undefined: Callable = Provide['undefined']
+
+
 class TestClass:
 
+    service: Service = Provide['service']
+    service_provider: Callable[..., Service] = Provider['service']
+    undefined: Callable = Provide['undefined']
+
     @inject
     def __init__(self, service: Service = Provide['service']):
         self.service = service

tests/unit/wiring/test_wiring_py36.py

@@ -6,6 +6,7 @@ import unittest
 from dependency_injector.wiring import (
     wire,
     Provide,
+    Provider,
     Closing,
     register_loader_containers,
     unregister_loader_containers,
@@ -64,6 +65,20 @@ class WiringTest(unittest.TestCase):
         service = test_function()
         self.assertIsInstance(service, Service)
 
+    def test_module_attributes_wiring(self):
+        self.assertIsInstance(module.service, Service)
+        self.assertIsInstance(module.service_provider(), Service)
+        self.assertIsInstance(module.undefined, Provide)
+
+    def test_module_attribute_wiring_with_invalid_marker(self):
+        from wiringsamples import module_invalid_attr_injection
+        with self.assertRaises(Exception) as context:
+            self.container.wire(modules=[module_invalid_attr_injection])
+        self.assertEqual(
+            str(context.exception),
+            'Unknown type of marker {0}'.format(module_invalid_attr_injection.service),
+        )
+
     def test_class_wiring(self):
         test_class_object = module.TestClass()
         self.assertIsInstance(test_class_object.service, Service)
@@ -97,6 +112,11 @@ class WiringTest(unittest.TestCase):
         service = instance.static_method()
         self.assertIsInstance(service, Service)
 
+    def test_class_attribute_wiring(self):
+        self.assertIsInstance(module.TestClass.service, Service)
+        self.assertIsInstance(module.TestClass.service_provider(), Service)
+        self.assertIsInstance(module.TestClass.undefined, Provide)
+
     def test_function_wiring(self):
         service = module.test_function()
         self.assertIsInstance(service, Service)
@@ -215,6 +235,18 @@ class WiringTest(unittest.TestCase):
         self.container.unwire()
         self.assertIsInstance(submodule.test_function(), Provide)
 
+    def test_unwire_module_attributes(self):
+        self.container.unwire()
+        self.assertIsInstance(module.service, Provide)
+        self.assertIsInstance(module.service_provider, Provider)
+        self.assertIsInstance(module.undefined, Provide)
+
+    def test_unwire_class_attributes(self):
+        self.container.unwire()
+        self.assertIsInstance(module.TestClass.service, Provide)
+        self.assertIsInstance(module.TestClass.service_provider, Provider)
+        self.assertIsInstance(module.TestClass.undefined, Provide)
+
     def test_wire_multiple_containers(self):
         sub_container = SubContainer()
         sub_container.wire(

tests/unit/wiring/test_wiring_string_ids_py36.py

@@ -4,7 +4,9 @@ import unittest
 from dependency_injector.wiring import (
     wire,
     Provide,
-    Closing)
+    Provider,
+    Closing,
+)
 from dependency_injector import errors
 
 # Runtime import to avoid syntax errors in samples on Python < 3.5
@@ -59,6 +61,11 @@ class WiringTest(unittest.TestCase):
         service = test_function()
         self.assertIsInstance(service, Service)
 
+    def test_module_attributes_wiring(self):
+        self.assertIsInstance(module.service, Service)
+        self.assertIsInstance(module.service_provider(), Service)
+        self.assertIsInstance(module.undefined, Provide)
+
     def test_class_wiring(self):
         test_class_object = module.TestClass()
         self.assertIsInstance(test_class_object.service, Service)
@@ -92,6 +99,11 @@ class WiringTest(unittest.TestCase):
         service = instance.static_method()
         self.assertIsInstance(service, Service)
 
+    def test_class_attribute_wiring(self):
+        self.assertIsInstance(module.TestClass.service, Service)
+        self.assertIsInstance(module.TestClass.service_provider(), Service)
+        self.assertIsInstance(module.TestClass.undefined, Provide)
+
     def test_function_wiring(self):
         service = module.test_function()
         self.assertIsInstance(service, Service)
@@ -210,6 +222,18 @@ class WiringTest(unittest.TestCase):
         self.container.unwire()
         self.assertIsInstance(submodule.test_function(), Provide)
 
+    def test_unwire_module_attributes(self):
+        self.container.unwire()
+        self.assertIsInstance(module.service, Provide)
+        self.assertIsInstance(module.service_provider, Provider)
+        self.assertIsInstance(module.undefined, Provide)
+
+    def test_unwire_class_attributes(self):
+        self.container.unwire()
+        self.assertIsInstance(module.TestClass.service, Provide)
+        self.assertIsInstance(module.TestClass.service_provider, Provider)
+        self.assertIsInstance(module.TestClass.undefined, Provide)
+
     def test_wire_multiple_containers(self):
         sub_container = SubContainer()
         sub_container.wire(