engine的portfolios和strategy里的portfolios两者是有什么区别和联系呢

[Junffzz]

BaseStrategy类下看到如下几个方法：

    def get_portfolio_value(self, gateway_name: str) -> float:
        return self.engine.portfolios[gateway_name].value

    def get_strategy_portfolio_value(self, gateway_name: str) -> float:
        return self.portfolios[gateway_name].value

    def get_account_balance(self, gateway_name: str) -> AccountBalance:
        return self.engine.portfolios[gateway_name].account_balance

    def get_strategy_account_balance(self, gateway_name: str) -> AccountBalance:
        return self.portfolios[gateway_name].account_balance

    def get_position(self, gateway_name: str) -> Position:
        return self.engine.portfolios[gateway_name].position

    def get_strategy_position(self, gateway_name: str) -> Position:
        return self.portfolios[gateway_name].position

不太理解，portfolios分别在engine里获取和策略里获取，是因为engine里的投资组合不同吗，在什么场景下使用呢，希望作者能帮忙解答