没优化之前: 嵌套if, 检查是否有中文字段值, 否则去查找英文值, 都没有则返回默认值

if record.City.Names["zh-CN"] == "" {
    city = record.City.Names["en"]
    if record.City.Names["en"] == "" {
        city = record.City.Names["en"]
    }
} else {
    city = "未知地域"
}

优化后: 平级if...else代替嵌套if

if name, ok: = record.City.Names["zh-CN"];
ok {
    city = name
} else if city, ok = record.City.Names["en"];
ok {
    city = record.City.Names["en"]
} else {
    city = "未知地域"
}

知识点: 利用go的ok模式,对查询map对象的值是否存在更加简洁和安全

更进一步的优化, 去掉else
这对else的处理逻辑有明确的值时非常有用

city = "未知地域"
if name, ok: = record.City.Names["zh-CN"];
ok {
    city = name
} else if name, ok = record.City.Names["en"];
ok {
    city = name
}

使用switch代替多个if分支: 根据成绩的分数段给出对应的等级

func calculateGrade(score int) string {
    var grade string
    // 堆代码 duidaima.com
    if score >= 90 && score <= 100 {
        grade = "A"
    } else if score >= 80 && score < 90 {
        grade = "B"
    } else if score >= 70 && score < 80 {
        grade = "C"
    } else if score >= 60 && score < 70 {
        grade = "D"
    } else if score >= 0 && score < 60 {
        grade = "F"
    } else {
        grade = "Invalid Score"
    }

    return grade
}

优化后: 使代码更加简洁，并且避免了多个嵌套的 if-else 语句。同时，使用 switch 语句还能够处理默认情况，即当 score 不满足任何一个分支条件时，默认返回 "Invalid Score" 。

func calculateGrade(score int) string {
    var grade string
    // 堆代码 duidaima.com
    switch {
        case score >= 90 && score <= 100:
            grade = "A"
        case score >= 80 && score < 90:
            grade = "B"
        case score >= 70 && score < 80:
            grade = "C"
        case score >= 60 && score < 70:
            grade = "D"
        case score >= 0 && score < 60:
            grade = "F"
        default:
            grade = "Invalid Score"
    }

    return grade
}

错误检查
首先看etcdgithub官网的错误处理例子:

resp, err: = cli.Put(ctx, "", "")
if err != nil {
    switch err {
        case context.Canceled:
            log.Fatalf("ctx is canceled by another routine: %v", err)
        case context.DeadlineExceeded:
            log.Fatalf("ctx is attached with a deadline is exceeded: %v", err)
        case rpctypes.ErrEmptyKey:
            log.Fatalf("client-side error: %v", err)
        default:
            log.Fatalf("bad cluster endpoints, which are not etcd servers: %v", err)
    }
}

我们可以进一步优化, 使用go自带的包errors对错误类型进行更加健壮的检查, 但是对开发者的要求较高, 需要预定义正确的错误类型, 来保证正确的比较错误

resp, err: = cli.Put(ctx, "", "")
if err2 != nil {
    switch {
        case errors.Is(err, context.Canceled):
            log.Fatalf("ctx is canceled by another routine: %v", err)
        case errors.Is(err, context.DeadlineExceeded):
            log.Fatalf("ctx is attached with a deadline is exceeded: %v", err)
        case errors.Is(err, rpctypes.ErrEmptyKey):
            log.Fatalf("client-side error: %v", err)
        default:
            log.Fatalf("bad cluster endpoints, which are not etcd servers: %v", err)
    }
}