Add example of callable delegation

docs/examples/index.rst

@@ -20,3 +20,4 @@ and powered by *Dependency Injector* framework.
     services_miniapp_v2
     bundles_miniapp
     use_cases_miniapp
+    password_hashing_miniapp

docs/examples/password_hashing_miniapp.rst

@@ -0,0 +1,19 @@
+Dependency injection and password hashing in Python
+===================================================
+
+Small example that demonstrates using of dependency injection for user
+password hashing.
+
+Instructions for running:
+
+.. code-block:: bash
+
+    python example.py
+
+Listing of ``example.py``:
+
+.. literalinclude:: ../../examples/miniapps/password_hashing/example.py
+   :language: python
+   :linenos:
+
+.. disqus::

docs/main/changelog.rst

@@ -9,9 +9,11 @@ follows `Semantic versioning`_
 
 Development version
 -------------------
-- Update main page example from "services" to "ioc_container".
+- Update main page example from "services_v1" to "services_v2".
 - Fix few typos on main page.
-- Add new example miniapp "ioc_container".
+- Add new example miniapp "password_hashing".
+- Add new example miniapp "services_v2".
+- Rename example miniapp "services" to "services_v1".
 - Fix incompatibility issue between Python 3.3, pip 10.0.0 and virtualenv
   16.0.0 (`details <https://github.com/awslabs/base64io-python/issues/4>`_)
   that caused failures of Python 3.3 tests on Travis.

examples/miniapps/password_hashing/README.rst

@@ -0,0 +1,12 @@
+Dependency injection and password hashing in Python
+===================================================
+
+Small example that demonstrates using of dependency injection for user
+password hashing.
+
+
+instructions for running:
+
+.. code-block:: bash
+
+    python example.py

examples/miniapps/password_hashing/example.py

@@ -0,0 +1,42 @@
+"""Example of dependency injection and password hashing in Python."""
+
+import passlib.hash
+
+import dependency_injector.containers as containers
+import dependency_injector.providers as providers
+
+
+class UsersService(object):
+    """Users service."""
+
+    def __init__(self, password_hasher):
+        """Initializer."""
+        self._password_hasher = password_hasher
+
+    def create_user(self, name, password):
+        """Create user with hashed password."""
+        hashed_password = self._password_hasher(password)
+        return dict(name=name, password=hashed_password)
+
+
+class Container(containers.DeclarativeContainer):
+    """Inversion of control container."""
+
+    password_hasher = providers.Callable(
+        passlib.hash.sha256_crypt.encrypt,
+        salt_size=16,
+        rounds=10000)
+
+    users_service = providers.Factory(
+        UsersService,
+        password_hasher=password_hasher.provider)
+
+
+if __name__ == '__main__':
+    container = Container()
+    users_service = container.users_service()
+
+    user1 = users_service.create_user(name='Roman', password='secret1')
+    user2 = users_service.create_user(name='Vitaly', password='secret2')
+
+    print(user1, user2)