通用地图值 [英] generic map value

问题描述

当我想以类似的方式使用地图键时，我遇到了几次这个问题，但是地图中的值是不同的.我以为我可以编写一个函数，将我想要的键类型与interface {}用作值类型，但是它不起作用.

I have run into this problem a few times when wanting to use keys of maps in a similar way but the values in the maps are different. I thought I could write a function that takes the key type I want with interface{} as the value type but it doesn't work.

func main() {
    mapOne := map[string]int
    mapTwo := map[string]double
    mapThree := map[string]SomeStruct

    useKeys(mapOne)
}
func useKeys(m map[string]interface{}) {
    //something with keys here
}

不确定是否有一种优雅的方法可以做到这一点，我只是觉得腰部饱满地将简单的东西重写为不同的值.

Not sure if there is an elegant way to do this I just feel waist full rewriting simple things for different values.

推荐答案

尽管go中的映射和切片本身是通用的，但它们不是协变的(它们也不是协变的，因为接口不是通用的).这是使用没有泛型的语言的一部分，您将不得不重复一些事情.

Though maps and slices in go are generic themselves, they are not covariant (nor could they be, since interfaces aren't generics). It's part of working with a language that doesn't have generics, you will have to repeat some things.

如果您真的只需要获取任何旧地图的键，则可以使用反射来做到这一点:

If you really just need to get the keys of any old map, you can use reflection to do so:

func useKeys(m interface{}) {
    v := reflect.ValueOf(m)
    if v.Kind() != reflect.Map {
        fmt.Println("not a map!")
        return
    }

    keys := v.MapKeys()
    fmt.Println(keys)
}

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