Add docs and the example

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)