Add example and docs

docs/providers/dict.rst

@@ -17,7 +17,21 @@ Dict provider
 
 ``Dict`` provider handles keyword arguments the same way as a :ref:`factory-provider`.
 
-.. note::
-    Positional argument are not supported.
+To use non-string keys or keys with ``.`` and ``-`` provide a dictionary as a positional argument:
+
+.. code-block:: python
+
+   providers.Dict({
+       SomeClass: providers.Factory(...),
+       'key.with.periods': providers.Factory(...),
+       'key-with-dashes': providers.Factory(...),
+   })
+
+Example:
+
+.. literalinclude:: ../../examples/providers/dict_non_string_keys.py
+   :language: python
+   :lines: 3-
+   :emphasize-lines: 40-43
 
 .. disqus::

examples/providers/dict_non_string_keys.py

@@ -0,0 +1,64 @@
+"""`Dict` provider with non-string keys example."""
+
+import dataclasses
+from typing import Dict
+
+from dependency_injector import containers, providers
+
+
+class Command:
+    ...
+
+
+class CommandA(Command):
+    ...
+
+
+class CommandB(Command):
+    ...
+
+
+class Handler:
+    ...
+
+
+class HandlerA(Handler):
+    ...
+
+
+class HandlerB(Handler):
+    ...
+
+
+@dataclasses.dataclass
+class Dispatcher:
+    command_handlers: Dict[Command, Handler]
+
+
+class Container(containers.DeclarativeContainer):
+
+    dispatcher_factory = providers.Factory(
+        Dispatcher,
+        command_handlers=providers.Dict({
+            CommandA: providers.Factory(HandlerA),
+            CommandB: providers.Factory(HandlerB),
+        }),
+    )
+
+
+if __name__ == '__main__':
+    container = Container()
+
+    dispatcher = container.dispatcher_factory()
+
+    assert isinstance(dispatcher.command_handlers, dict)
+    assert isinstance(dispatcher.command_handlers[CommandA], HandlerA)
+    assert isinstance(dispatcher.command_handlers[CommandB], HandlerB)
+
+    # Call "dispatcher = container.dispatcher_factory()" is equivalent to:
+    # dispatcher = Dispatcher(
+    #     command_handlers={
+    #         CommandA: HandlerA(),
+    #         CommandB: HandlerB(),
+    #     },
+    # )