Reflection with the `reflect` Package

Reflection Basics

This lesson explains the main concept clearly with beginner-friendly examples and background so you can learn why the code works.

reflect lets you inspect types at runtime – useful for generic libraries.

func Dump(v interface{}) {
    rv := reflect.ValueOf(v)
    rt := rv.Type()
    fmt.Printf("type: %s, kind: %s\n", rt, rt.Kind())
    for i := 0; i < rv.NumField(); i++ {
        f := rt.Field(i)
        val := rv.Field(i).Interface()
        fmt.Printf("%s = %v\n", f.Name, val)
    }
}

Setting values via reflection

func SetField(obj interface{}, name string, value interface{}) error {
    rv := reflect.ValueOf(obj).Elem()
    fv := rv.FieldByName(name)
    if !fv.IsValid() || !fv.CanSet() { return fmt.Errorf("cannot set %s", name) }
    fv.Set(reflect.ValueOf(value))
    return nil
}