lib/errrors: implement method As

The As method will set the target to instance of E only if only target
is **E.

1 files changed, 14 insertions, 0 deletions

diff --git a/lib/errors/errors.go b/lib/errors/errors.go
index 35b74d1c..b9a5b9bd 100644
--- a/lib/errors/errors.go
+++ b/lib/errors/errors.go
@@ -7,6 +7,7 @@ package errors
 
 import (
 	"net/http"
+	"reflect"
 )
 
 //
@@ -58,6 +59,19 @@ func (e *E) Error() string {
 }
 
 //
+// As set the target to e only if only target is **E.
+//
+func (e *E) As(target interface{}) bool {
+	_, ok := target.(**E)
+	if ok {
+		val := reflect.ValueOf(target)
+		val.Elem().Set(reflect.ValueOf(e))
+		return ok
+	}
+	return false
+}
+
+//
 // Unwrap return the internal error.
 //
 func (e *E) Unwrap() error {