Fix recursive copying issue in `Delegate` provider

docs/main/changelog.rst

@@ -9,6 +9,9 @@ follows `Semantic versioning`_
 
 Development version
 -------------------
+- Fix recursive copying issue in ``Delegate`` provider.
+  See issue: `#245 <https://github.com/ets-labs/python-dependency-injector/issues/245>`_.
+  Thanks to `@GitterRemote <https://github.com/GitterRemote>`_ for reporting the issue.
 - Add docs and example for ``Factory.add_attributes()`` method.
 - Remove legacy css file.
 

src/dependency_injector/providers.pyi

@@ -91,9 +91,10 @@ class Self(Provider[T]):
 
 
 class Delegate(Provider[Provider]):
-    def __init__(self, provides: Provider) -> None: ...
+    def __init__(self, provides: Optional[Provider] = None) -> None: ...
     @property
-    def provides(self) -> Provider: ...
+    def provides(self) -> Optional[Provider]: ...
+    def set_provides(self, provides: Optional[Provider]): ...
 
 
 class Dependency(Provider[T]):

src/dependency_injector/providers.pyx

@@ -519,13 +519,14 @@ cdef class Delegate(Provider):
         :type: object
     """
 
-    def __init__(self, provides):
+    def __init__(self, provides=None):
         """Initializer.
 
         :param provides: Value that have to be provided.
         :type provides: :py:class:`Provider`
         """
-        self.__provides = ensure_is_provider(provides)
+        self.__provides = None
+        self.set_provides(provides)
         super(Delegate, self).__init__()
 
     def __deepcopy__(self, memo):
@@ -534,8 +535,11 @@ cdef class Delegate(Provider):
         if copied is not None:
             return copied
 
-        copied = self.__class__(deepcopy(self.__provides, memo))
+        copied = self.__class__()
+        memo[id(self)] = copied
 
+        if self.provides:
+            copied.set_provides(deepcopy(self.provides, memo))
         self._copy_overridings(copied, memo)
 
         return copied
@@ -556,9 +560,13 @@ cdef class Delegate(Provider):
 
     @property
     def provides(self):
-        """Return provider."""
         return self.__provides
 
+    def set_provides(self, provides):
+        if provides:
+            provides = ensure_is_provider(provides)
+        self.__provides = provides
+
     @property
     def related(self):
         """Return related providers generator."""