Good day,

Studying Go, trying to figure out reflection

There is an example:

package main import ( "flag" "fmt" "reflect" ) type AppConfig struct { Pg string `cli:"pg" env:"PG" default:"host=host.local dbname=db user=user password=password" description:"Connection to PostgreSQL"` } func main() { config := &AppConfig{} GetConfig(config) fmt.Println(config.Pg) } func GetConfig(config interface{}) interface{} { e := reflect.ValueOf(config).Elem() t := e.Type() flag.StringVar( e.Field(0).Interface().(*string), t.Field(0).Tag.Get("cli"), t.Field(0).Tag.Get("default"), t.Field(0).Tag.Get("description")) flag.Parse() return config }

Link to the playground https://play.golang.org/p/KmQDYJaizl

When starting, I expect to receive:

 panic: interface conversion: interface {} is string, not *string

If we replace e.Field(0).Interface().(*string) on the correct one (from my point of view) &e.Field(0).Interface().(string) I get:

 main.go:22: cannot take the address of e.Field(0).Interface().(string)

Actually the question is what is not understood correctly? Or what am I doing wrong?

    1 answer 1

    If you need an address, then take Addr . Replace

     e.Field(0).Interface().(*string),

    on

     e.Field(0).Addr().Interface().(*string),

    Playground: https://play.golang.org/p/3APNXAtooK .

    • Thanks, I tried using .Pointer (), but .Addr () did not consider - chernomyrdin