In this function I get "s declared and not used" which I don't understand - do I need to somehow tag it as 'really I used it' or something?
func getString(data map[string]interface{}, name string) (string, error) {
s := data[name]
if reflect.TypeOf(s).Kind() != reflect.String {
return s.(string), nil
}
return "", &apiError{1, "it's not a string"}
}
Oddly, I don't get the error from this function:
func getInt(data map[string]interface{}, name string) (int, error) {
t := data[name]
if reflect.TypeOf(t).Kind() == reflect.Int {
return t.(int), nil
}
return 0, &apiError{1, "it's not an int"}
}
Also, any thoughts on the right way to factor these into a single function would be welcomed!
Your error comes from (declaring and not) using the same identifier elsewhere because this compiles and runs fine on golang.org:
package main
import "reflect"
func main() {
m := make(map[string]interface{})
m["foo"] = "25"
getString(m, "foo")
}
func getString(data map[string]interface{}, name string) (string, error) {
s := data[name]
if reflect.TypeOf(s).Kind() != reflect.String {
return s.(string), nil
}
return "", nil
}
Your code looks correct, error isn't reproducible. Sure you can refactor these into a single function, but you may not like it depending of tastes.
type VType int
const (
VInteger VType = iota
VString
VUnknown
)
func getValue(data map[string]interface{}, name string) (VType, int, string) {
switch v := data[name].(type) {
case int:
return VInteger, v, ""
case string:
return VString, 0, v
default:
return VUnknown, 0, ""
}
}
func main() {
m := make(map[string]interface{})
m["foo"] = "25"
switch t, i, s := getValue(m, "foo"); t {
case VInteger:
fmt.Println("int ", i) //do something with int
case VString:
fmt.Println("string ", s) //do something with string
case VUnknown:
err := &apiError{1, "it's not an int"} //do something with err
}
}