self.main_engine.send_email(subject, msg)的疑问

main_engine类型为MianEngine，我看了一下MianEngine类，它并没有send_email的方法。
send_email方法是在 engine.py的class EmailEngine里，
所以我的疑问是：
self.main_engine.send_email(subject, msg)是不是写错了。

class CtaEngine(BaseEngine)
def init(self, main_engine: MainEngine, event_engine: EventEngine) -> None:
""""""
super().init(main_engine, event_engine, APP_NAME)

def send_email(self, msg: str, strategy: CtaTemplate = None) -> None:
    """
    Send email to default receiver.
    """
    if strategy:
        subject: str = f"{strategy.strategy_name}"
    else:
        subject: str = "CTA策略引擎"

    self.main_engine.send_email(subject, msg)

EmailEngine类在初始化时有self.main_engine.send_email = self.send_email，让main_engine能够直接调用EmailEngine的send_email方法。

Rekel wrote:

EmailEngine类在初始化时有self.main_engine.send_email = self.send_email，让main_engine能够直接调用EmailEngine的send_email方法。

谢谢大侠，明白了！非常感谢您！