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

问题描述

我写了一些代码，我需要它来捕获这些参数并将它们传递给 fmt.Println

（我希望它的默认值行为，写出由空格分隔的参数，然后是换行符）。然而它需要 [] interface {} 但是 flag.Args（）返回一个 []字符串。

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()...)
}

返回以下错误：

This returns the following error:

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

中的接口{}这是一个错误吗？不应该 fmt.Println 带任何数组？顺便说一下，我也试过这样做：

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())

但我得到以下错误：

but I get the following error:

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

是否有一个Go方法来解决这个问题？

Is there a "Go" way to workaround this?

推荐答案

一个错误。 fmt.Println（）需要一个 []接口{} 类型。这意味着，它必须是界面{} 值的一部分，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...)

您无法使用任何切片的原因是在 []字符串和 []接口{} 之间的转换需要更改内存布局，并且发生在准时。将类型转换为 interface {} 需要O（1）次。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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