Add set_value to Scope.

README.md

@@ -733,12 +733,14 @@ fn main() -> Result<(), EvalAltResult>
     // First create the state
     let mut scope = Scope::new();
 
-    // Then push some initialized variables into the state
-    // NOTE: Remember the system number types in Rhai are i64 (i32 if 'only_i32') ond f64.
-    //       Better stick to them or it gets hard working with the script.
+    // Then push (i.e. add) some initialized variables into the state.
+    // Remember the system number types in Rhai are i64 (i32 if 'only_i32') ond f64.
+    // Better stick to them or it gets hard working with the script.
     scope.push("y", 42_i64);
     scope.push("z", 999_i64);
-    scope.push("s", "hello, world!".to_string());   // remember to use 'String', not '&str'
+
+    // 'set_value' adds a variable when one doesn't exist
+    scope.set_value("s", "hello, world!".to_string());  // remember to use 'String', not '&str'
 
     // First invocation
     engine.eval_with_scope::<()>(&mut scope, r"
@@ -749,10 +751,14 @@ fn main() -> Result<(), EvalAltResult>
     // Second invocation using the same state
     let result = engine.eval_with_scope::<i64>(&mut scope, "x")?;
 
-    println!("result: {}", result);                 // prints 979
+    println!("result: {}", result);                     // prints 979
 
-    // Variable y is changed in the script
-    assert_eq!(scope.get_value::<i64>("y").expect("variable x should exist"), 1);
+    // Variable y is changed in the script - read it with 'get_value'
+    assert_eq!(scope.get_value::<i64>("y").expect("variable y should exist"), 1);
+
+    // We can modify scope variables directly with 'set_value'
+    scope.set_value("y", 42_i64);
+    assert_eq!(scope.get_value::<i64>("y").expect("variable y should exist"), 42);
 
     Ok(())
 }