I m trying to assign a pointer to a struct to the value of an already initialized struct pointer of the same type.
To do a simple service locator
Code is like this
package main
import (
"fmt"
"reflect"
)
type Concrete struct {}
func (c *Concrete) Do(){}
type Doer interface {
Do()
}
func main() {
l := ServiceLocator{}
l.Register(&Concrete{})
var x Doer
if l.Get(&x); x!= nil {
fmt.Println("by interface pointer ok")
}
// This is not possible in my understanding
//var z Doer
//if l.Get(z); z!= nil {
// fmt.Println("by interface ok")
//}
var y *Concrete
if l.Get(y); y!= nil {
fmt.Println("by struct pointer ok")
}
}
type ServiceLocator struct {
services []interface{}
types []reflect.Type
values []reflect.Value
}
func (s *ServiceLocator) Register(some interface{}) {
s.services = append(s.services, some)
s.types = append(s.types, reflect.TypeOf(some))
s.values = append(s.values, reflect.ValueOf(some))
}
func (s *ServiceLocator) Get(some interface{}) interface{} {
k := reflect.TypeOf(some).Elem()
kind := reflect.TypeOf(some).Elem().Kind()
for i, t := range s.types {
if kind==reflect.Interface && t.Implements(k) {
reflect.Indirect(
reflect.ValueOf(some),
).Set(s.values[i])
} else if kind==reflect.Struct && k.AssignableTo(t.Elem()) {
fmt.Println(reflect.ValueOf(some).Elem().CanAddr())
fmt.Println(reflect.ValueOf(some).Elem().CanSet())
fmt.Println(reflect.Indirect(reflect.ValueOf(some)))
reflect.ValueOf(some).Set(s.values[i])
}
}
return nil
}
Despite my attempts i keep getting runtime errors such
panic: reflect: reflect.Value.Set using unaddressable value
try the play here
need help, thanks a lot!
With JimB helps and information here is the fixed play https://play.golang.org/p/_g2AbX0yHV