将 [] 字符串转换为 [] 接口{}

Question

I just want to write some code like this:

func (w Writer) WriteVString(strs []string) (int, error) {
    return writeV(func(index int, str interface{}) (int, error) {
        return w.WriteString(str.(string))
    }, strs) // it doesn't work
}

func (w Writer) WriteV(bs [][]byte) (int, error) {
    return writeV(func(index int, b interface{}) (int, error) {
        return w.Write(b.([]byte))
    }, []interface{}{bs...}) // it also can't be compiled
}
type writeFunc func(int, interface{}) (int, error)

func writeV(fn writeFunc, slice []interface{}) (n int, err error) {
    var m int
    for index, s := range slice {
        if m, err = fn(index, s); err != nil {
            break
        }
        n += m
    )
    return
}

I thought interface{} can represent any type, so []interface can also represent any []type before, now I know I'm wrong, []type is a whole type, can't be considered as []interface{} .

So, can anyone help me how to make this code work, or any other solution?

PS : I know that []byte or string can be converted to one another, but it's not actually my intention, may be there is another type rather than []byte and string .

Answer 1

now I know I'm wrong, []type is a whole type, can't be considered as []interface{} .

Yes, and that is because interface{} is its own type (and not an "alias" for any other type).
As I mention in " what is the meaning of interface{} in golang? " (if v is a interface{} variable):

Beginner gophers are led to believe that “ v is of any type”, but that is wrong.
v is not of any type; it is of interface{} type.

The FAQ mentions

they do not have the same representation in memory .

It is necessary to copy the elements individually to the destination slice .
This example converts a slice of int to a slice of interface{} :

t := []int{1, 2, 3, 4}
s := make([]interface{}, len(t))
for i, v := range t {
    s[i] = v
}

Answer 2

1. Create a utility function, like this

func ToGenericArray(arr ...interface{}) []interface{} {
    return arr
}

2. And use it:

func yourfunc(arr []interface{})  {
....
}

yourfunc(ToGenericArray([...]string{"a", "b", "c"}))

3. IMPORTANT NOTICE: the following will not work

func yourfunc(arr []interface{})  {
....
}

arr:=[...]string{"a", "b", "c"}

yourfunc(ToGenericArray(arr))

Answer 3

With generics, useful with sql package

func toAnyList[T any](input []T) []any{
    list := make([]any, len(input))
    for i, v := range input {
        list[i] = v
    }
    return list
}