Better API for Scope.

tests/var_scope.rs

@@ -14,3 +14,38 @@ fn test_var_scope() -> Result<(), EvalAltResult> {
 
     Ok(())
 }
+
+#[test]
+fn test_scope_eval() -> Result<(), EvalAltResult> {
+    let mut engine = Engine::new();
+
+    // First create the state
+    let mut scope = Scope::new();
+
+    // Then push some initialized variables into the state
+    // NOTE: Remember the default numbers used by Rhai are i64 and f64.
+    //       Better stick to them or it gets hard to work with other variables in the script.
+    scope.push("y".into(), 42_i64);
+    scope.push("z".into(), 999_i64);
+
+    // First invocation
+    engine
+        .eval_with_scope::<()>(
+            &mut scope,
+            r"
+                let x = 4 + 5 - y + z;
+                y = 1;
+            ",
+        )
+        .expect("y and z not found?");
+
+    // Second invocation using the same state
+    if let Ok(result) = engine.eval_with_scope::<i64>(&mut scope, "x") {
+        println!("result: {}", result); // should print 966
+    }
+
+    // Variable y is changed in the script
+    assert_eq!(scope.get_value::<i64>("y").unwrap(), 1);
+
+    Ok(())
+}