如何使用Go语言编写上门做菜系统中的配送员评价模块？

type Evaluation struct {
    ID        int     // 评价ID
    OrderID   int     // 订单ID
    DeliveryID int    // 配送员ID
    Rating    int     // 评分
    Comment   string  // 评论
    Timestamp time.Time // 时间戳
}

var evaluations []Evaluation

func AddEvaluation(evaluation Evaluation) {
    evaluations = append(evaluations, evaluation)
}

func GetEvaluationsByDeliveryID(deliveryID int) []Evaluation {
    var result []Evaluation
    for _, evaluation := range evaluations {
        if evaluation.DeliveryID == deliveryID {
            result = append(result, evaluation)
        }
    }
    return result
}

func GetAverageRatingByDeliveryID(deliveryID int) float64 {
    var totalRating int
    var count int
    for _, evaluation := range evaluations {
        if evaluation.DeliveryID == deliveryID {
            totalRating += evaluation.Rating
            count++
        }
    }
    if count == 0 {
        return 0.0
    }
    return float64(totalRating) / float64(count)
}

func ProcessOrder(orderID int, deliveryID int) {
    // 订单处理逻辑...

    // 评价配送员
    rating := 5
    comment := "配送员服务很好！"
    evaluation := Evaluation{
        ID:        len(evaluations) + 1,
        OrderID:   orderID,
        DeliveryID: deliveryID,
        Rating:    rating,
        Comment:   comment,
        Timestamp: time.Now(),
    }
    AddEvaluation(evaluation)
}

func GetDeliveryRating(deliveryID int) {
    evaluations := GetEvaluationsByDeliveryID(deliveryID)
    averageRating := GetAverageRatingByDeliveryID(deliveryID)
    
    // 利用评价信息进行业务处理...
}