python-dependency-injector/README.rst
2016-10-06 23:15:41 +03:00

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Dependency Injector - Python dependency injection framework
===========================================================
*Dependency Injector* is a Python dependency injection framework. It was
designed to be unified, developer-friendly tool that helps to implement
dependency injection pattern in formal, pretty, Pythonic way.
*Dependency Injector* framework key features are:
+ Easy, smart, pythonic style.
+ Obvious, clear structure.
+ Extensibility and flexibility.
+ Memory efficiency.
+ Thread safety.
+ Documentation.
+ Semantic versioning.
Status
------
+---------------------------------------+----------------------------------------------------------------------------------------+
| *PyPi* | .. image:: https://img.shields.io/pypi/v/dependency_injector.svg |
| | :target: https://pypi.python.org/pypi/dependency_injector/ |
| | :alt: Latest Version |
| | .. image:: https://img.shields.io/pypi/l/dependency_injector.svg |
| | :target: https://pypi.python.org/pypi/dependency_injector/ |
| | :alt: License |
+---------------------------------------+----------------------------------------------------------------------------------------+
| *Python versions and implementations* | .. image:: https://img.shields.io/pypi/pyversions/dependency_injector.svg |
| | :target: https://pypi.python.org/pypi/dependency_injector/ |
| | :alt: Supported Python versions |
| | .. image:: https://img.shields.io/pypi/implementation/dependency_injector.svg |
| | :target: https://pypi.python.org/pypi/dependency_injector/ |
| | :alt: Supported Python implementations |
+---------------------------------------+----------------------------------------------------------------------------------------+
| *Builds and tests coverage* | .. image:: https://travis-ci.org/ets-labs/python-dependency-injector.svg?branch=master |
| | :target: https://travis-ci.org/ets-labs/python-dependency-injector |
| | :alt: Build Status |
| | .. image:: https://coveralls.io/repos/ets-labs/python-dependency-injector/badge.svg |
| | :target: https://coveralls.io/r/ets-labs/python-dependency-injector |
| | :alt: Coverage Status |
+---------------------------------------+----------------------------------------------------------------------------------------+
Installation
------------
*Dependency Injector* library is available on `PyPi`_::
pip install dependency_injector
Dependency Injection
--------------------
Inversion of control
--------------------
Example of dependency injection
-------------------------------
Brief example below demonstrates usage of *Dependency Injector* containers and
providers for definition of several IoC containers for some microservice
system:
.. code-block:: python
"""Example of dependency injection in Python."""
import logging
import sqlite3
import boto.s3.connection
import example.main
import example.services
import dependency_injector.containers as containers
import dependency_injector.providers as providers
class Platform(containers.DeclarativeContainer):
"""IoC container of platform service providers."""
logger = providers.Singleton(logging.Logger, name='example')
database = providers.Singleton(sqlite3.connect, ':memory:')
s3 = providers.Singleton(boto.s3.connection.S3Connection,
aws_access_key_id='KEY',
aws_secret_access_key='SECRET')
class Services(containers.DeclarativeContainer):
"""IoC container of business service providers."""
users = providers.Factory(example.services.Users,
logger=Platform.logger,
db=Platform.database)
auth = providers.Factory(example.services.Auth,
logger=Platform.logger,
db=Platform.database,
token_ttl=3600)
photos = providers.Factory(example.services.Photos,
logger=Platform.logger,
db=Platform.database,
s3=Platform.s3)
class Application(containers.DeclarativeContainer):
"""IoC container of application component providers."""
main = providers.Callable(example.main.main,
users_service=Services.users,
auth_service=Services.auth,
photos_service=Services.photos)
Next example demonstrates run of dependency injection example application
defined above:
.. code-block:: python
"""Run dependency injection example application.
Instructions for running:
python run.py 1 secret photo.jpg
"""
import sys
import logging
from containers import Platform, Application
if __name__ == '__main__':
# Configure platform logger:
Platform.logger().addHandler(logging.StreamHandler(sys.stdout))
# Run application:
Application.main(uid=sys.argv[1],
password=sys.argv[2],
photo=sys.argv[3])
# Previous call is an equivalent of next operations:
#
# logger = logging.Logger(name='example')
# database = sqlite3.connect(':memory:')
# s3 = boto.s3.connection.S3Connection(aws_access_key_id='KEY',
# aws_secret_access_key='SECRET')
#
# example.main.main(uid=sys.argv[1],
# password=sys.argv[2],
# photo=sys.argv[3],
# users_service=example.services.Users(logger=logger,
# db=database),
# auth_service=example.services.Auth(logger=logger,
# db=database,
# token_ttl=3600),
# photos_service=example.services.Photos(logger=logger,
# db=database,
# s3=s3))
#
# Output:
#
# User 1 has been found in database
# User 1 has been successfully authenticated
# Photo photo.jpg has been successfully uploaded by user 1
Alternative definition styles of providers
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*Dependecy Injector* supports few other styles of dependency injections
definition.
IoC containers from previous example could look like these:
.. code-block:: python
class Platform(containers.DeclarativeContainer):
"""IoC container of platform service providers."""
logger = providers.Singleton(logging.Logger) \
.add_kwargs(name='example')
database = providers.Singleton(sqlite3.connect) \
.add_args(':memory:')
s3 = providers.Singleton(boto.s3.connection.S3Connection) \
.add_kwargs(aws_access_key_id='KEY',
aws_secret_access_key='SECRET')
or like this these:
.. code-block:: python
class Platform(containers.DeclarativeContainer):
"""IoC container of platform service providers."""
logger = providers.Singleton(logging.Logger)
logger.add_kwargs(name='example')
database = providers.Singleton(sqlite3.connect)
database.add_args(':memory:')
s3 = providers.Singleton(boto.s3.connection.S3Connection)
s3.add_kwargs(aws_access_key_id='KEY',
aws_secret_access_key='SECRET')
You can get more *Dependency Injector* examples in ``/examples`` directory on
GitHub:
https://github.com/ets-labs/python-dependency-injector
Documentation
-------------
*Dependency Injector* documentation is hosted on ReadTheDocs:
- `User's guide`_
- `API docs`_
Feedback
--------
Feel free to post questions, bugs, feature requests, proposals etc. on
*Dependency Injector* GitHub Issues:
https://github.com/ets-labs/python-dependency-injector/issues
Your feedback is quite important!
.. _PyPi: https://pypi.python.org/pypi/dependency_injector
.. _User's guide: http://python-dependency-injector.ets-labs.org/en/stable/
.. _API docs: http://python-dependency-injector.ets-labs.org/en/stable/api/