Just implement update logic in Methods where it is needed, since if there is no pointer I cannot hand it to any function or method

date.go

@@ -24,15 +24,6 @@ func NewDate(t time.Time) *Date {
 	}
 }
 
-// Update updates the Date.
-func (d *Date) Update() {
-	if d == nil {
-		d = NewDate(time.Now())
-	} else {
-		d.DateTime = DateTime(time.Now())
-	}
-}
-
 // Check checks the Date for incompatibilities with RFC4287. It returns an
 // error.
 func (d *Date) Check() error {