Option result and error

16_interfaces/option_result.v

@@ -0,0 +1,47 @@
+struct User{
+	id int
+	name string
+}
+
+struct Repo{
+	users []User
+}
+
+fn (r Repo) find_user_by_id(id int) !User{
+	for user in r.users {
+		if user.id == id {
+			return user
+		}
+	}
+	return error('User ${id} not found')
+}
+
+fn (r Repo) find_user_by_id2(id int) ?User{
+	for user in r.users {
+		if user.id == id {
+			return user
+		}
+	}
+	return none
+}
+
+fn main(){
+	repo := Repo{
+		users: [User{1, 'Andrew'},
+				User{2, 'Bob'},
+				User{10, 'Charles'}
+				]
+	}
+
+	user := repo.find_user_by_id(10) or {
+		println(err)
+		return
+	}
+
+	println(user.id)
+	println(user.name)
+
+	user2 := repo.find_user_by_id2(10) or { return }
+
+	println(user2)
+}