Add .provides attribute to singleton providers

docs/main/changelog.rst

@@ -7,6 +7,12 @@ that were made in every particular version.
 From version 0.7.6 *Dependency Injector* framework strictly 
 follows `Semantic versioning`_
 
+Development version
+-------------------
+- Add ``.provides`` attribute to ``Singleton`` and its subclasses.
+  It's a consistency change to make ``Singleton`` match ``Callable``
+  and ``Factory`` interfaces.
+
 4.13.2
 ------
 - Fix PyCharm typing warning "Expected type 'Optional[Iterable[ModuleType]]',

src/dependency_injector/providers.pyi

@@ -242,6 +242,8 @@ class BaseSingleton(Provider[T]):
     @property
     def cls(self) -> T: ...
     @property
+    def provides(self) -> T: ...
+    @property
     def args(self) -> Tuple[Injection]: ...
     def add_args(self, *args: Injection) -> BaseSingleton[T]: ...
     def set_args(self, *args: Injection) -> BaseSingleton[T]: ...

src/dependency_injector/providers.pyx

@@ -2283,7 +2283,12 @@ cdef class BaseSingleton(Provider):
     @property
     def cls(self):
         """Return provided type."""
-        return self.__instantiator.cls
+        return self.provides
+
+    @property
+    def provides(self):
+        """Return provided type."""
+        return self.__instantiator.provides
 
     @property
     def args(self):
@@ -2388,7 +2393,7 @@ cdef class BaseSingleton(Provider):
     @property
     def related(self):
         """Return related providers generator."""
-        yield from filter(is_provider, [self.__instantiator.provs])
+        yield from filter(is_provider, [self.__instantiator.provides])
         yield from filter(is_provider, self.args)
         yield from filter(is_provider, self.kwargs.values())
         yield from filter(is_provider, self.attributes.values())