di_3.py

import pinject
import os
class Repository:
    def __init__(self, db: str):
        self.db = db
    def get_data(self):
        return 'Hello World'
class RepositoryBindingSpec(pinject.BindingSpec):
    def provide_repository(self):
        return Repository(db=os.getenv('dbname'))
class Service:
    def __init__(self, repository: Repository):
        self.repository = repository
    def process(self):
        return self.repository.get_data()
class UI:
    def __init__(self, service: Service):
        self.service = service
    def render(self):
        print(self.service.process())

if __name__ == '__main__':
    object_graph = pinject.new_object_graph(binding_specs=[RepositoryBindingSpec()])
    ui = object_graph.provide(UI)
    ui.render()