mainline 0.2.3

Simple yet powerful python dependency injection for py2/py3k

mainline
========

Simple yet powerful python dependency injection.

Tested with Python 2.7+ (including py3k).

Installation
------------

```sh
pip install mainline
```

Examples
--------

### Simple factory registration and resolution of an instance

```py
from mainline import DI
di = Di()

# The default scope is singleton, but you can also use thread, process (really only usable while forking), and any object that supports a MutableMapping interface.
@di.register_factory('apple', scope='singleton')
def apple():
return 'apple'

assert di.resolve('apple') == 'apple'
```

### Simple instance registration

```py
from mainline import DI
di = Di()

apple = object()
di.set_instance('apple', apple)
assert di.resolve('apple') == apple

# If no factory is registered already with this key, one is created using the optional default_scope keyword argument, which defaults to singleton.
banana = object()
di.set_instance('banana', banana, default_scope='singleton')
assert di.resolve('banana') == banana
```

### Injection of positional and keyword arguments

```py
from mainline import DI
di = Di()

@di.register_factory('apple')
def apple():
return 'apple'

@di.inject('apple')
def injected(apple):
return apple

assert injected() == apple()

@di.inject('apple')
def injected(apple, arg1):
return apple, arg1

assert injected('arg1') == (apple(), 'arg1')

@di.register_factory('banana')
@di.inject('apple')
def banana(apple):
return 'banana', apple

@di.inject('apple', omg='banana')
def injected(apple, arg1, omg=None):
return apple, arg1, omg

assert injected('arg1') == (apple(), 'arg1', banana())

@di.register_factory('orange')
@di.inject('apple', not_an_apple='banana')
def orange(apple, not_an_apple):
return 'orange', not_an_apple

@di.inject('apple', 'orange', omg='banana')
def injected(apple, orange, arg1, omg=None):
return apple, orange, arg1, omg

assert injected('arg1') == (apple(), orange(), 'arg1', banana())

'''
Provider keys don't have to be strings
'''

class Test(object):
pass

# Thread scopes are stored in a thread local
@di.register_factory(Test, scope='thread')
def test_factory():
return Test()

@di.inject(Test)
def injected(test):
return test

assert isinstance(injected(), Test)

'''
Injection on object init
'''

@di.inject('apple')
class Injectee(object):
def __init__(self, apple):
self.apple = apple

assert Injectee().apple == apple()
```

### Injection as a classproperty

```py
from mainline import DI
di = Di()

@di.register_factory('apple')
def apple():
return 'apple'

@di.inject_classproperty('apple')
class Injectee(object):
pass

assert Injectee.apple == apple()
```

### Auto injection based on name in argspec

Do yourself a favor and use this sparingly. The magic on this one is real.

```py
from mainline import DI
di = Di()

@di.register_factory('apple')
def apple():
return 'apple'

@di.auto_inject()
def injected(apple):
return apple

assert injected() == apple()

@di.auto_inject('apple')
def injected(apple, arg1):
return apple, arg1

assert injected('arg1') == (apple(), 'arg1')

@di.register_factory('banana')
@di.auto_inject()
def banana(apple):
return 'banana', apple

@di.auto_inject()
def injected(apple, arg1, banana=None):
return apple, arg1, banana

assert injected('arg1') == (apple(), 'arg1', banana())
```

Running tests
-------------

```sh
# From git checkout:
python setup.py test
```