无法将 [] 字符串转换为 [] 接口 {} [英] Cannot convert []string to []interface {}

问题描述

我正在编写一些代码，我需要它来捕获参数并将它们传递给 fmt.Println
(我想要它的默认行为，编写由空格分隔并后跟换行符的参数).但是它需要 []interface {} 但 flag.Args() 返回一个 []string.
下面是代码示例:

I'm writing some code, and I need it to catch the arguments and pass them through fmt.Println
(I want its default behaviour, to write arguments separated by spaces and followed by a newline). However it takes []interface {} but flag.Args() returns a []string.
Here's the code example:

package main

import (
    "fmt"
    "flag"
)

func main() {
    flag.Parse()
    fmt.Println(flag.Args()...)
}

这会返回以下错误:

./example.go:10: cannot use args (type []string) as type []interface {} in function argument

这是一个错误吗?fmt.Println 不应该采用 any 数组吗?顺便说一句，我也尝试过这样做:

Is this a bug? Shouldn't fmt.Println take any array? By the way, I've also tried to do this:

var args = []interface{}(flag.Args())

但我收到以下错误:

cannot convert flag.Args() (type []string) to type []interface {}

是否有解决此问题的Go"方式?

Is there a "Go" way to workaround this?

推荐答案

这不是错误.fmt.Println() 需要 []interface{} 类型.这意味着，它必须是 interface{} 值的切片，而不是任何切片".为了转换切片，您需要循环并复制每个元素.

This is not a bug. fmt.Println() requires a []interface{} type. That means, it must be a slice of interface{} values and not "any slice". In order to convert the slice, you will need to loop over and copy each element.

old := flag.Args()
new := make([]interface{}, len(old))
for i, v := range old {
    new[i] = v
}
fmt.Println(new...)

您不能使用任何切片的原因是 []string 和 []interface{} 之间的转换需要更改内存布局并发生在 O(n) 时间内.将类型转换为 interface{} 需要 O(1) 时间.如果他们不需要这个 for 循环，编译器仍然需要插入它.

The reason you can't use any slice is that conversion between a []string and a []interface{} requires the memory layout to be changed and happens in O(n) time. Converting a type to an interface{} requires O(1) time. If they made this for loop unnecessary, the compiler would still need to insert it.

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