Implement lazy initialization and improve copying for ProvidedInstance provider

src/dependency_injector/containers.c

@@ -1389,12 +1389,12 @@ struct __pyx_obj_19dependency_injector_9providers_Selector {
  * # Provided instance
  * 
  * cdef class ProvidedInstance(Provider):             # <<<<<<<<<<<<<<
- *     cdef Provider __provider
+ *     cdef object __provides
  * 
  */
 struct __pyx_obj_19dependency_injector_9providers_ProvidedInstance {
   struct __pyx_obj_19dependency_injector_9providers_Provider __pyx_base;
-  struct __pyx_obj_19dependency_injector_9providers_Provider *__pyx___provider;
+  PyObject *__pyx___provides;
 };
 
 
@@ -2144,7 +2144,7 @@ static struct __pyx_vtabstruct_19dependency_injector_9providers_Selector *__pyx_
  * # Provided instance
  * 
  * cdef class ProvidedInstance(Provider):             # <<<<<<<<<<<<<<
- *     cdef Provider __provider
+ *     cdef object __provides
  * 
  */
 

src/dependency_injector/providers.pxd

@@ -235,7 +235,7 @@ cdef class Selector(Provider):
 # Provided instance
 
 cdef class ProvidedInstance(Provider):
-    cdef Provider __provider
+    cdef object __provides
 
     cpdef object _provide(self, tuple args, dict kwargs)
 

src/dependency_injector/providers.pyi

@@ -423,10 +423,13 @@ class ProvidedInstanceFluentInterface:
     def __getattr__(self, item: Any) -> AttributeGetter: ...
     def __getitem__(self, item: Any) -> ItemGetter: ...
     def call(self, *args: Injection, **kwargs: Injection) -> MethodCaller: ...
+    @property
+    def provides(self) -> Optional[Provider]: ...
+    def set_provides(self, provides: Optional[Provider]) -> ProvidedInstanceFluentInterface: ...
 
 
 class ProvidedInstance(Provider, ProvidedInstanceFluentInterface):
-    def __init__(self, provider: Provider) -> None: ...
+    def __init__(self, provides: Optional[Provider] = None) -> None: ...
 
 
 class AttributeGetter(Provider, ProvidedInstanceFluentInterface):

src/dependency_injector/providers.pyx

@@ -3886,23 +3886,22 @@ cdef class ProvidedInstance(Provider):
     - :py:class:`Dependency`
     """
 
-    def __init__(self, provider):
+    def __init__(self, provides=None):
-        self.__provider = provider
+        self.__provides = None
+        self.set_provides(provides)
         super().__init__()
 
     def __repr__(self):
-        return f'{self.__class__.__name__}(\'{self.__provider}\')'
+        return f'{self.__class__.__name__}(\'{self.__provides}\')'
 
     def __deepcopy__(self, memo=None):
-        cdef ProvidedInstance copied
-
         copied = memo.get(id(self))
         if copied is not None:
             return copied
 
-        return self.__class__(
+        copied = _memorized_duplicate(self, memo)
-            deepcopy(self.__provider, memo),
+        copied.set_provides(_copy_if_provider(self.provides, memo))
-        )
+        return copied
 
     def __getattr__(self, item):
         return AttributeGetter(self, item)
@@ -3912,8 +3911,13 @@ cdef class ProvidedInstance(Provider):
 
     @property
     def provides(self):
-        """Return provider."""
+        """Return provider's provides."""
-        return self.__provider
+        return self.__provides
+
+    def set_provides(self, provides):
+        """Set provider's provides."""
+        self.__provides = provides
+        return self
 
     def call(self, *args, **kwargs):
         return MethodCaller(self, *args, **kwargs)
@@ -3921,11 +3925,12 @@ cdef class ProvidedInstance(Provider):
     @property
     def related(self):
         """Return related providers generator."""
-        yield self.__provider
+        if is_provider(self.provides):
+            yield self.provides
         yield from super().related
 
     cpdef object _provide(self, tuple args, dict kwargs):
-        return self.__provider(*args, **kwargs)
+        return self.__provides(*args, **kwargs)
 
 
 cdef class AttributeGetter(Provider):

tests/unit/providers/test_provided_instance_py2_py3.py

@@ -69,6 +69,16 @@ class ProvidedInstanceTests(unittest.TestCase):
     def setUp(self):
         self.container = Container()
 
+    def test_lazy_init(self):
+        provides = providers.Object(object())
+        provider = providers.ProvidedInstance()
+        provider.set_provides(provides)
+        self.assertIs(provider.provides, provides)
+
+    def test_set_provides_returns_self(self):
+        provider = providers.ProvidedInstance()
+        self.assertIs(provider.set_provides(providers.Provider()), provider)
+
     def test_is_provider(self):
         self.assertTrue(providers.is_provider(self.container.service.provided))