add example

Cargo.toml

@@ -205,6 +205,11 @@ name = "promises_ruby"
 path = "examples/ruby/promises.rs"
 required-features = ["ruby"]
 
+[[example]]
+name = "side_effects_ruby"
+path = "examples/ruby/side_effects.rs"
+required-features = ["ruby"]
+
 [dev-dependencies]
 tracing-subscriber = "0.3.18"
 mlua = { version = "0.9.8", features = ["luajit", "vendored", "send"] }

assets/examples/ruby/side_effects.rb

@@ -0,0 +1 @@
+spawn_entity()

examples/ruby/side_effects.rs

@@ -0,0 +1,41 @@
+use bevy::{app::AppExit, prelude::*};
+use bevy_scriptum::prelude::*;
+use bevy_scriptum::runtimes::ruby::prelude::*;
+
+fn main() {
+    App::new()
+        // This is just needed for headless console app, not needed for a regular bevy game
+        // that uses a winit window
+        .set_runner(move |mut app: App| loop {
+            app.update();
+            if let Some(exit) = app.should_exit() {
+                return exit;
+            }
+        })
+        .add_plugins(DefaultPlugins)
+        .add_systems(Startup, startup)
+        .add_systems(Update, print_entity_names_and_quit)
+        .add_scripting::<RubyRuntime>(|runtime| {
+            runtime.add_function(String::from("spawn_entity"), spawn_entity);
+        })
+        .run();
+}
+
+fn spawn_entity(mut commands: Commands) {
+    commands.spawn(Name::new("SpawnedEntity"));
+}
+
+fn startup(mut commands: Commands, assets_server: Res<AssetServer>) {
+    commands.spawn((Script::<RubyScript>::new(
+        assets_server.load("examples/ruby/side_effects.rb"),
+    ),));
+}
+
+fn print_entity_names_and_quit(query: Query<&Name>, mut exit: EventWriter<AppExit>) {
+    if !query.is_empty() {
+        for e in &query {
+            println!("{}", e);
+        }
+        exit.write(AppExit::Success);
+    }
+}