pip install CNSdi   Build Status

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"CNSdi" is a simple Python dependency injection library, build for simplicity of use. Services can be identified through id and namespace.


    

  

  

  

    

      

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 Decorator imports 

    

    

      
from di.decorator import service, inject

    

  

  

  

    

      

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 Service examples 

    

    

      

    

  

  

  

    

      

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Create a service with an id of a.service that, when retrieved, will return the a_service function, unmolested.

    

    

      
@service('a.service')
def a_service():
    return "I am a service"

    

  

  

  

    

      

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Create a service that will return an instantiated object.  This time, the namespace is explicitly set for the service.

    

    

      
@service('another.service', to_namespace='not.the.default.namespace')
class AnotherService(object):
    pass

    

  

  

  

    

      

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 Inject examples 

    

    

      

    

  

  

  

    

      

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Since a.service stores a function, you can call it like any other function.  The raw function stored as a.service is injected into this function.

    

    

      
@inject(['a.service'])
def func(svc):
    return svc()

    

  

  

  

    

      

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func() == "I am a service"

    

  

  

  

    

      

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class InjectedObject(object):

    

  

  

  

    

      

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You can inject into an class too, just do it in the constructor or any other function in the class.

    

    

      
    @inject(['a.service'])
    def __init__(self, svc):
        self.msg = svc()
        
    def get_message():
        return self.msg

    

  

  

  

    

      

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InjectedObject().get_message() == "I am a service"

    

  

  

  

    

      

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Services can have injected functions as well.  It just works.

    

    

      
@service('a.object.service')
class InjectedServiceObject(object):
    @inject(['a.service'])
    def __init__(self, svc):
        self.msg = svc()
    def get_message():
        return self.msg

    

  

  

  

    

      

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 Use helpers! 

    

    

      
from di.helpers import add_service, get_service

    

  

  

  

    

      

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Helpers help make things a little easier for procedural code.  Here you can grab a service and start using it immediately.  No additional wiring needed.

    

    

      
get_service('a.object.service').get_message() == "I am a service"

    

  

  

  

    

      

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So let's say you have a file that imports and collects all your services.

    

    

      
from markdown import markdown
add_service('markdown', markdown)

    

  

  

  

    

      

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In another file, you can call up that service and use it immediately.

    

    

      
'<h1>Hello World!</h1>' == get_service('markdown')('#Hello World!')

    

  

  

  

    

      

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Then you decide you want to use a different markdown renderer.

    

    

      
from my.markdown.renderer import render
add_service('markdown', render)

    

  

  

  

    

      

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You call the same code in the other file, and it should work the same!

    

    

      
'<h1>Hello World!</h1>' == get_service('markdown')('#Hello World!')