simple-dependency-injection

simple-dependency-injection

simple-dependency-injection is a library is lightweight library to apply dependency injection pattern in a simple way.

Note: simple-dependency-injection is in a development state, there were some checks to finish the first version

Install

You can install it through pip

pip install simple-dependency-injection

Use

To use simple-dependency-injection only have to create a dependency container and register your dependencies.

The library check types of parameters and result, its important typing that.

That is an example of dependency container configuration

from abc import ABC, abstractmethod
from simple_dependency_injection.dependency_container import DependencyContainer

class ConfigDependencyInterface(ABC):
    @abstractmethod
    def get_percent_benefit(self) -> float:
        pass

class ConfigDependency(ConfigDependencyInterface):
    def get_percent_benefit(self) -> float:
        return 10.0
   
def config_generator() -> ConfigDependencyInterface:
    return ConfigDependency()

class ServiceInterface(ABC):
    def __init__(self, config: ConfigDependencyInterface):
        self.config = config

    @abstractmethod
    def calculate_benefit(self, amount: float) -> float:
        pass

class Service(ServiceInterface):
    def calculate_benefit(self, amount: float) -> float:
        return amount * (self.config.get_percent_benefit() / 100)
  
def service_generator(config: ConfigDependencyInterface) -> ServiceInterface:
    return Service(config=config)

dependency_container = DependencyContainer()
dependency_container.register_dependency(
    ConfigDependencyInterface, config_generator
)
dependency_container.register_dependency(
    ServiceInterface, service_generator
)

Once the dependency container is created, you can use it with inject decorator.

@dependency_container.inject
def main(service: ServiceInterface):
    service.calculate_benefit(10)

main()

Other way to use the dependency container is get the dependency directly

dependency_container.get_dependency(ServiceInterface).calculate_benefit(10)

For testing is easy override dependencies

class ConfigToTestDependency(ConfigDependencyInterface):
    def get_percent_benefit(self) -> float:
        return 0.0

def test_config_generator() -> ConfigDependencyInterface:
    return ConfigToTestDependency()

with dependency_container.test_container() as dependency_container_test:
    dependency_container_test.override(
        ConfigDependencyInterface, test_config_generator
    )
    main()