我如何创建通用功能来接收Go lang中的地图？

Question

how can i pass map data in to a general function (isExist) to check, the given value is exist or not passing map type may be map[int]int or map[string]string or any

func IsExist(text int, data map[interface{}]interface{}) bool {

    for key, _ := range data {

        if data[key] == text {

            return true

        }

    }

    return false

}

func main() {

    var data = make(map[string]int)

    //var data =map[interface {}]interface{}  this case will working fine

    data["a"] = 1

    data["b"] = 2

    fmt.Println(IsExist(2, data))
    //throwing error that 'cannot use data (type map[string]int) as type  map[interface {}]interface {} in argument to IsExist'

}

please let me know how can you generalize it?

Answer 1

Go's type system can't do that. map[string]int and map[interface {}]interface{} are distinct types. Besides, storage/representation of objects in memory depends on the type. A string has one memory layout. But the very same string, packaged as a interface{} - totally different. For the same reasons you can't "cast" a []int to a []interface{}. You have to copy the elements into the new slice.

Same here. Either make your map a map[interface {}]interface{} from the start, or copy all key-values pairs to one, prior to the call of the generic function.