from injection import injectable, inject, singleton @singleton class Printer: def __init__(self): self.history = [] def print(self, message: str): self.history.append(message) print(message) @injectable class Service: def __init__(self, printer: Printer): self.printer = printer def hello(self): self.printer.print("Hello world!") @inject def main(service: Service): service.hello() if __name__ == "__main__": main()