Add example and docs

docs/providers/dict.rst

@@ -0,0 +1,23 @@
+Dict provider
+=============
+
+.. meta::
+   :keywords: Python,DI,Dependency injection,IoC,Inversion of Control,Dict,Injection
+   :description: Dict provider helps to inject a dictionary of the dependencies. This page demonstrates
+                 how to use Dict provider.
+
+.. currentmodule:: dependency_injector.providers
+
+:py:class:`Dict` provider provides a dictionary of values.
+
+.. literalinclude:: ../../examples/providers/dict.py
+   :language: python
+   :lines: 3-
+   :emphasize-lines: 21-24
+
+``Dict`` provider handles keyword arguments the same way as a :ref:`factory-provider`.
+
+.. note::
+    Positional argument are not supported.
+
+.. disqus::

docs/providers/index.rst

@@ -43,6 +43,7 @@ Providers module API docs - :py:mod:`dependency_injector.providers`
     coroutine
     object
     list
+    dict
     configuration
     selector
     dependency

examples/providers/dict.py

@@ -0,0 +1,45 @@
+"""`Dict` provider example."""
+
+import dataclasses
+from typing import Dict
+
+from dependency_injector import containers, providers
+
+
+@dataclasses.dataclass
+class Module:
+    name: str
+
+
+@dataclasses.dataclass
+class Dispatcher:
+    modules: Dict[str, Module]
+
+
+class Container(containers.DeclarativeContainer):
+
+    dispatcher_factory = providers.Factory(
+        Dispatcher,
+        modules=providers.Dict(
+            module1=providers.Factory(Module, name='m1'),
+            module2=providers.Factory(Module, name='m2'),
+        ),
+    )
+
+
+if __name__ == '__main__':
+    container = Container()
+
+    dispatcher = container.dispatcher_factory()
+
+    assert isinstance(dispatcher.modules, dict)
+    assert dispatcher.modules['module1'].name == 'm1'
+    assert dispatcher.modules['module2'].name == 'm2'
+
+    # Call "dispatcher = container.dispatcher_factory()" is equivalent to:
+    # dispatcher = Dispatcher(
+    #     modules={
+    #         'module1': Module(name='m1'),
+    #         'module2': Module(name='m2'),
+    #     },
+    # )