python-inject is a fast and simple to use python dependency injection
framework. It uses decorators and descriptors to reference external
dependencies, and scopes to specify objects life-cycles.
python-inject has been created to provide the pythonic way of dependency
injection, utilizing specific Python functionality.
- Project's site: http://code.google.com/p/python-inject
- User's Guide: http://code.google.com/p/python-inject/wiki/UsersGuide
- Tutorial: http://code.google.com/p/python-inject/wiki/Tutorial
- API: http://api.python-inject.googlecode.com/hg/html/index.html
- Source code: http://github.com/ivan-korobkov/python-inject
Fast and easy to use.
Attribute and argument injections:
class My(object): attr = inject.attr(A) attr2 = inject.named_attr('attr2', B) attr3 = inject.class_attr(C) @inject.param('param', D): def myfunc(param): passNormal way of instantiating objects,
Class(*args, **kwargs).Autobinding.
Application, thread and request scopes.
Request scope middleware for WSGI and Django applications.
Easy integration into existing projects.
You can find this file in examples/simple.py:
"""Basic python-inject example, execute it to see the output.
All memcached, redis and mail classes are dummy classes that do not connect
to anything. They are only used to demonstrate the dependency injection
principle and python-inject functionality.
"""
import inject
class Memcached(object):
"""Dummy memcached backend, always returns None."""
def __init__(self, host, port):
print 'Connected memcached to %s:%s' % (host, port)
def get(self, key):
"""Always return None."""
return None
class Redis(object):
"""Redis backend, always returns a new User instance for any key."""
def __init__(self, host, port):
print 'Connected redis to %s:%s' % (host, port)
def get(self, key):
return User("Ivan Korobkov", "[email protected]")
class MailService(object):
"""Sends emails."""
def send(self, email, text):
"""send an email."""
print "Sent an email to %s, text=%s." % (email, text)
class User(object):
"""Example model."""
# Both Redis and Memcached are injected as class attributes
# so they can be accessed from the classmethods.
redis = inject.class_attr(Redis)
memcached = inject.class_attr(Memcached)
# MailService is injected as a normal attribute, it can be accessed
# only from the normal (bound) methods, not classmethods.
mail_service = inject.attr(MailService)
@classmethod
def get_by_id(cls, id):
"""Get a user from memcached, if not present fallback to redis."""
key = 'user-%s' % id
user = cls.memcached.get(key)
if user:
return user
user = cls.redis.get(key)
print 'Loaded %s from redis.' % user
return user
def __init__(self, name, email):
self.name = name
self.email = email
def __str__(self):
return '<User "%s">' % self.name
@inject.param("hello_text")
def greet(self, hello_text):
"""Send a greeting email to the user.
@param hello_text: Demonstrates injecting params into functions.
"""
text = hello_text % self.name
self.mail_service.send(self.email, text)
if __name__ == '__main__':
"""Register an injector, configure the bindings and send a greeting
email to a user. Usually, you should store your bindings in another
function (or functions) in another module.
For example:
# bindings.py
def config(injector):
config_redis(injector)
config_memcached(injector)
# etc.
def config_redis(injector)
redis = Redis('myhost', 1234)
injector.bind(Redis, redis)
def config_memached(injector):
memcached = Memcached('myhost', 2345)
injector.bind(Memcached, memcached)
"""
injector = inject.Injector()
injector.register()
memcached = Memcached('localhost', 2345)
redis = Redis('localhost', 1234)
injector.bind(Redis, redis)
injector.bind(Memcached, memcached)
injector.bind("hello_text", "Hello, %s!")
user = User.get_by_id(10)
user.greet()
MIT License, see LICENSE.