Convert []string to []interface{}

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 } 

---

Tom L propose this example (in the comments):

package main  import "fmt"  func main() {      x := []string{"a", "b", "c", "d"}     fmt.Printf("%T: %v\n", x, x)      //converting a []string to a []interface{}     y := make([]interface{}, len(x))     for i, v := range x {         y[i] = v     }     fmt.Printf("%T: %v\n", y, y)      //converting a []interface{} to a []string     z := make([]string, len(y))     for i, v := range y {         z[i] = fmt.Sprint(v)     }     fmt.Printf("%T: %v\n", z, z)  } 

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))