Add massive update of README examples

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Roman Mogilatov 2016-12-27 23:06:40 +02:00
parent e37a8cee3b
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@ -104,8 +104,124 @@ Dependency injection pattern provides the following advantages:
Example of dependency injection Example of dependency injection
------------------------------- -------------------------------
Brief example below demonstrates usage of *Dependency Injector* for creating Let's go through next example:
several IoC containers for some example application:
.. image:: https://raw.githubusercontent.com/wiki/ets-labs/python-dependency-injector/img/engines_cars/diagram.png
:width: 100%
:align: center
Listing of ``example.engines`` module:
.. code-block:: python
"""Dependency injection example, engines module."""
class Engine(object):
"""Example engine base class.
Engine is a heart of every car. Engine is a very common term and could be
implemented in very different ways.
"""
class GasolineEngine(Engine):
"""Gasoline engine."""
class DieselEngine(Engine):
"""Diesel engine."""
class ElectroEngine(Engine):
"""Electro engine."""
Listing of ``example.cars`` module:
.. code-block:: python
"""Dependency injection example, cars module."""
class Car(object):
"""Example car."""
def __init__(self, engine):
"""Initializer."""
self._engine = engine # Engine is injected
Next example demonstrates creation of several cars with different engines:
.. code-block:: python
"""Dependency injection example, Cars & Engines."""
import example.cars
import example.engines
if __name__ == '__main__':
gasoline_car = example.cars.Car(example.engines.GasolineEngine())
diesel_car = example.cars.Car(example.engines.DieselEngine())
electro_car = example.cars.Car(example.engines.ElectroEngine())
While previous example demonstrates advantages of dependency injection, there
is a disadvantage demonstration as well - creation of car requires additional
code for specification of dependencies. Nevertheless, this disadvantage could
be easily avoided by using a dependency injection framework for creation of
inversion of control container (IoC container).
Example of creation of several inversion of control containers (IoC containers)
using *Dependency Injector*:
.. code-block:: python
"""Dependency injection example, Cars & Engines IoC containers."""
import example.cars
import example.engines
import dependency_injector.containers as containers
import dependency_injector.providers as providers
class Engines(containers.DeclarativeContainer):
"""IoC container of engine providers."""
gasoline = providers.Factory(example.engines.GasolineEngine)
diesel = providers.Factory(example.engines.DieselEngine)
electro = providers.Factory(example.engines.ElectroEngine)
class Cars(containers.DeclarativeContainer):
"""IoC container of car providers."""
gasoline = providers.Factory(example.cars.Car,
engine=Engines.gasoline)
diesel = providers.Factory(example.cars.Car,
engine=Engines.diesel)
electro = providers.Factory(example.cars.Car,
engine=Engines.electro)
if __name__ == '__main__':
gasoline_car = Cars.gasoline()
diesel_car = Cars.diesel()
electro_car = Cars.electro()
Dependency injection in action
------------------------------
Brief example below is a simplified version of inversion of control
containters from one of the real-life applications. This example demonstrates
usage of *Dependency Injector* inversion of control containers & providers
for specifying all application components and their dependencies beetween
each other in one module. Besides other listed above advantages, it gives a
great opportunity to control & manage application's structure in one place.
.. code-block:: python .. code-block:: python