Implement lazy initialization and improve copying for Object provider

src/dependency_injector/providers.pyi

@@ -79,7 +79,9 @@ class Provider(Generic[T]):
 
 
 class Object(Provider[T]):
-    def __init__(self, provides: T) -> None: ...
+    def __init__(self, provides: Optional[T] = None) -> None: ...
+    def provides(self) -> Optional[T]: ...
+    def set_provides(self, provides: Optional[T]) -> Object: ...
 
 
 class Self(Provider[T]):

src/dependency_injector/providers.pyx

@@ -400,13 +400,10 @@ cdef class Object(Provider):
         :type: object
     """
 
-    def __init__(self, provides):
-        """Initializer.
-
-        :param provides: Value that have to be provided.
-        :type provides: object
-        """
-        self.__provides = provides
+    def __init__(self, provides=None):
+        """Initialize provider."""
+        self.__provides = None
+        self.set_provides(provides)
         super(Object, self).__init__()
 
     def __deepcopy__(self, memo):
@@ -415,7 +412,8 @@ cdef class Object(Provider):
         if copied is not None:
             return copied
 
-        copied = self.__class__(self.__provides)
+        copied = _memorized_duplicate(self, memo)
+        copied.set_provides(self.provides)
 
         self._copy_overridings(copied, memo)
 
@@ -435,6 +433,16 @@ cdef class Object(Provider):
         """
         return self.__str__()
 
+    @property
+    def provides(self):
+        """Return provider's provides."""
+        return self.__provides
+
+    def set_provides(self, provides):
+        """Set provider's provides."""
+        self.__provides = provides
+        return self
+
     @property
     def related(self):
         """Return related providers generator."""

tests/unit/providers/test_base_py2_py3.py

@@ -152,6 +152,17 @@ class ObjectProviderTests(unittest.TestCase):
     def test_is_provider(self):
         self.assertTrue(providers.is_provider(providers.Object(object())))
 
+    def test_init_optional_provides(self):
+        instance = object()
+        provider = providers.Object()
+        provider.set_provides(instance)
+        self.assertIs(provider.provides, instance)
+        self.assertIs(provider(), instance)
+
+    def test_set_provides_returns_self(self):
+        provider = providers.Object()
+        self.assertIs(provider.set_provides(object()), provider)
+
     def test_provided_instance_provider(self):
         provider = providers.Object(object())
         self.assertIsInstance(provider.provided, providers.ProvidedInstance)