如何检查 interface{} 是否为切片 [英] How to check if interface{} is a slice

问题描述

我是围棋的菜鸟 :) 所以我的问题可能很愚蠢，但找不到答案，所以.

I'm noob in Go :) so my question may be stupid, but can't find answer, so.

我需要一个函数:

func name (v interface{}) {
    if is_slice() {
        for _, i := range v {
            my_var := i.(MyInterface)
            ... do smth
        }
    } else {
        my_var := v.(MyInterface)
        ... do smth
    }
}

如何在 Go 中执行 is_slice?感谢任何帮助.

How can I do is_slice in Go? Appreciate any help.

推荐答案

在你的情况下 类型开关 是最简单最方便的解决方案:

In your case the type switch is the simplest and most convenient solution:

func name(v interface{}) {
    switch x := v.(type) {
    case []MyInterface:
        fmt.Println("[]MyInterface, len:", len(x))
        for _, i := range x {
            fmt.Println(i)
        }
    case MyInterface:
        fmt.Println("MyInterface:", x)
    default:
        fmt.Printf("Unsupported type: %T
", x)
    }
}

case 分支枚举了可能的类型，其中的 x 变量已经属于该类型，因此您可以使用它.

The case branches enumerate the possible types, and inside them the x variable will already be of that type, so you can use it so.

测试它:

type MyInterface interface {
    io.Writer
}

var i MyInterface = os.Stdout
name(i)
var s = []MyInterface{i, i}
name(s)
name("something else")

输出(在 Go Playground 上试试):

Output (try it on the Go Playground):

MyInterface: &{0x1040e110}
[]MyInterface, len: 2
&{0x1040e110}
&{0x1040e110}
Unsupported type: string

对于单一类型检查，您还可以使用 类型断言:

For a single type check you may also use type assertion:

if x, ok := v.([]MyInterface); ok {
    // x is of type []MyInterface
    for _, i := range x {
        fmt.Println(i)
    }
} else {
    // x is not of type []MyInterface or it is nil
}

还有其他方法，使用包reflect可以写一个更通用(也更慢)的解决方案，但如果你刚刚开始 Go，你不应该深入研究反射.

There are also other ways, using package reflect you can write a more general (and slower) solution, but if you're just starting Go, you shouldn't dig into reflection yet.

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