Dependency injection example 1

di_1.py

class Repository:
    def __init__(self):
        self.db = os.getenv('dbname')
    def get_data(self):
        return 'Hello World'
class Service:
    def __init__(self):
        self.repository = Repository()
    def process(self):
        return self.dal.get_data()
class UI:
    def __init__(self):
        self.service = Service()
    def render(self):
        print(self.service.process())

if __name__ == '__main__':
    ui = UI()
    ui.render()