Adding injections example

README.md

@@ -73,12 +73,60 @@ arguments, other are using attributes or methods to be initialized. Injection,
 in terms of `Objects`, is an instruction how to provide dependency for the 
 particular object.
 
-Every Python object could be an injection value. Special case is a `Objects` 
-provider as an injection value. In such case, injection value is a result of 
+Every Python object could be an injection's value. Special case is a `Objects` 
+provider as an injection's value. In such case, injection value is a result of 
 injectable provider call (every time injection is done).
 
 Injections are used by providers.
 
+```python
+"""`KwArg` and `Attribute` injections example."""
+
+import sqlite3
+
+from objects.providers import Singleton
+from objects.providers import NewInstance
+
+from objects.injections import KwArg
+from objects.injections import Attribute
+
+
+class ObjectA(object):
+
+    """ObjectA has dependency on database."""
+
+    def __init__(self, database):
+        """Initializer.
+
+        Database dependency need to be injected via init arg."""
+        self.database = database
+
+    def get_one(self):
+        """Select one from database and return it."""
+        return self.database.execute('SELECT 1').fetchone()[0]
+
+
+# Database and `ObjectA` providers.
+database = Singleton(sqlite3.Connection,
+                     KwArg('database', ':memory:'),
+                     KwArg('timeout', 30),
+                     KwArg('detect_types', True),
+                     KwArg('isolation_level', 'EXCLUSIVE'),
+                     Attribute('row_factory', sqlite3.Row))
+
+object_a = NewInstance(ObjectA,
+                       KwArg('database', database))
+
+# Creating several `ObjectA` instances.
+object_a_1 = object_a()
+object_a_2 = object_a()
+
+# Making some asserts.
+assert object_a_1 is not object_a_2
+assert object_a_1.database is object_a_2.database
+assert object_a_1.get_one() == object_a_2.get_one() == 1
+```
+
 ### Catalogs
 
 Catalogs are named set of providers.

examples/readme/injections.py

@@ -0,0 +1,45 @@
+"""`KwArg` and `Attribute` injections example."""
+
+import sqlite3
+
+from objects.providers import Singleton
+from objects.providers import NewInstance
+
+from objects.injections import KwArg
+from objects.injections import Attribute
+
+
+class ObjectA(object):
+
+    """ObjectA has dependency on database."""
+
+    def __init__(self, database):
+        """Initializer.
+
+        Database dependency need to be injected via init arg."""
+        self.database = database
+
+    def get_one(self):
+        """Select one from database and return it."""
+        return self.database.execute('SELECT 1').fetchone()[0]
+
+
+# Database and `ObjectA` providers.
+database = Singleton(sqlite3.Connection,
+                     KwArg('database', ':memory:'),
+                     KwArg('timeout', 30),
+                     KwArg('detect_types', True),
+                     KwArg('isolation_level', 'EXCLUSIVE'),
+                     Attribute('row_factory', sqlite3.Row))
+
+object_a = NewInstance(ObjectA,
+                       KwArg('database', database))
+
+# Creating several `ObjectA` instances.
+object_a_1 = object_a()
+object_a_2 = object_a()
+
+# Making some asserts.
+assert object_a_1 is not object_a_2
+assert object_a_1.database is object_a_2.database
+assert object_a_1.get_one() == object_a_2.get_one() == 1