EasyDI

Python Dependency Configuration ( Injection ) Library

Installation

pip3 install easydi

Usage

Assume you have this project structure

my_project
|- my_project
    |- __init__.py
    |- my_module.py
    |- config.py
    |- dependency.py
    |- __main__.py
|- setup.py

Create a config class in config.py

# Config must implement below method
class MyConfig:
    def get(self, name, placeholder, value_format):
        return value

Create dependency.py

# Import all your module
from my_project.my_module import *
from my_project.config import MyConfig

from easydi import *

container = Container()

container.register(MyConfig, _config=True)
container.register(MyClass, DependencyConfig("my.config", "placeholder"))
...

Use in your _main_.py

from dependency import container

def main():
    # Init config instance before using other class
    config = container.my_project.MyConfig.instance()

    # Run your application
    your_class = container.my_project.MyClass.instance()
    your_class.run()

if __name__ == "__main__":
    main()

Container

Format to registering an object to a container is:

( <object>, *<dependency object>, <_config|_group|_alias> )

• object : class object, not initiate
• dependency object (optional) : see Dependency Object
• _config (optional) : mark object as config, there can be only one object. must implement * get(name, placeholder, value_format) * method. Will be use by DependencyConfig
• _group (optional) : mark object as specific group. Will be use by DependencyGroup
• _alias (optional) : give an alias name to an object

Container can be merge with other container if required, note that same path will be overwritten

containerA = Container()
containerB = Container()
containerA.update(containerB)

Retrieving instance from container

When retrieving from container you will be given an ObjectFactory, this is a wrapper for your object. To retrieve your object you can use one of this method ( assuming f is the ObjectFactory ) :

• f.instance(*args, **kwargs) : Return single instance
• f.build(*args, **kwargs) : Return new instance
• f(_build=False, *args, **kwargs) : same as f.instance(*args, **kwargs)
• f(_build=True, *args, **kwargs) : same as f.build(*args, **kwargs)
• f(*args, **kwargs) : same as f.instance(*args, **kwargs)

Passing additional arguments or keyword arguments is possible when using instance() ( first time only ) or build()

Dependency Object

• Dependency : Default type if nothing is specified
• DependencyConfig : To retrieve value from user defined config
• DependencyPath : Retrieve object by it's full path
• DependencyCallback : Return object from a custom function
• DependencyGroup : Pass multiple registered object as list