go - 如何将值附加到 ...interface{}？

Question

这是我要模拟的示例函数:

package main

import "fmt"

func main() {
    fmt.Println(fmt.Sprintf("Initially I want %d %s", 2, "dogs"))
    fmt.Println(Sprintf2("Now I want %d %s", 2, "dogs"))
}

func Sprintf2(format string, a ...interface{}) string {

return fmt.Sprintf(format + " and %d cats", append(a, 5))
}

这是 playground 中的一个链接:https://play.golang.org/p/dHDwTlbRLDu

预期输出:

Initially I want 2 dogs
Now I want 2 dogs and 5 cats

实际输出:

Initially I want 2 dogs
Now I want [2 %!d(string=dogs) 5] %!s(MISSING) and %!d(MISSING) cats

Answer 1

您需要先将新值附加到 a slice ，然后在调用 fmt.Sprintf 时解压 slice :

func Sprintf2(format string, a ...interface{}) string {
    a = append(a, 5)
    return fmt.Sprintf(format+" and %d cats", a...)
}

https://play.golang.org/p/YRWzAT2Yxm_q