Easy-DI

Easy-DI is an easy to use Dependency Injection library.

Easy-DI allows you to implement the Dependency Injection pattern and manage the complexity of your Python applications.

Installing Easy-DI and Supported Versions

Easy-DI is available on PyPI:

$ python -m pip install easy-dependency-injection

Easy-DI officially supports Python 3.8+.

Key characteristics

• Lightweight: the added overhead is comparable to accessing a module's constants
• mypy-friendly: allows your IDE to infer the type of injected resources and help you with auto-complete and type hinting
• Does one thing, does it well: it's just a dependency injection library.
• Not invasive: you won't have to rewrite your application to use it; you can start taking advantage of the inversion of control gradually
• Test-friendly: easy to integrate in your unit tests.

Known limitations

• Only classes can be injected: no functions, no modules
• Not tested with metaclasses
• Performances decrease linearly with the number of injected resources

Example

from easy_di import DI, inject, injected


class Swallow:
    velocity: injected(str)

    def answer(self):
        return f"My airspeed velocity is {self.velocity}"

# this is needed only because the Swallow class is in the __main__ module,
# more realistic scenarios won't need the `inject` function call
inject(__name__)

if __name__ == "__main__":
    DI.register("velocity", "24 miles per hour")
    print(Swallow().answer())