2 files changed, 10 insertions, 0 deletions
diff --git a/CLI/rust/src/game_of_life.rs b/CLI/rust/src/game_of_life.rs
index c854e7f..4b1e979 100644
--- a/CLI/rust/src/game_of_life.rs
+++ b/CLI/rust/src/game_of_life.rs
@@ -66,6 +66,7 @@ pub(crate) fn options() -> Result<ArgMatches, Error> {
                 .short('d')
                 .long("delay")
                 .default_value("50")
+                .validator(opts::validators::is_positive)
                 .display_order(6)
         )
         .get_matches();
diff --git a/CLI/rust/src/game_of_life/opts.rs b/CLI/rust/src/game_of_life/opts.rs
index c0ece98..5e52715 100644
--- a/CLI/rust/src/game_of_life/opts.rs
+++ b/CLI/rust/src/game_of_life/opts.rs
@@ -37,4 +37,13 @@ pub(crate) mod validators {
             Err(e) => Err(e.to_string()),
         }
     }
+
+    /// Validator to check if delay value is positive
+    pub(crate) fn is_positive(val: &str) -> Result<(), String> {
+        match val.parse::<i16>() {
+            Ok(n) if n.is_positive() => Ok(()),
+            Ok(_) => Err(String::from("must be postive value (so far)")),
+            Err(e) => Err(e.to_string()),
+        }
+    }
 }