Added a generic systems example to the examples folder in bevy.

Cargo.toml

@@ -303,6 +303,10 @@ path = "examples/ecs/timers.rs"
 name = "query_bundle"
 path = "examples/ecs/query_bundle.rs"
 
+[[example]]
+name = "generic_systems"
+path = "examples/ecs/generic_systems.rs"
+
 # Games
 [[example]]
 name = "alien_cake_addict"

examples/ecs/generic_systems.rs

@@ -0,0 +1,26 @@
+use bevy::prelude::*;
+use bevy::ecs::component::Component;
+
+struct A;
+struct B;
+
+fn spawn_entities_on_click<T: Component, const N: usize>(
+    mut cmds: Commands,
+    mouse_button_inputs: Res<Input<MouseButton>>,
+) {
+    if mouse_button_inputs.just_pressed(MouseButton::Left) {
+        for _ in 0..N {
+            cmds.spawn().insert(T).id();
+        }
+        info!("spawned {} entities with component {}", N, std::any::type_name::<T>());
+    }
+}
+
+
+fn main() {
+    App::build()
+        .add_plugins(DefaultPlugins)
+        .add_system(spawn_entities_on_click::<A>.system())
+        .add_system(spawn_entities_on_click::<B>.system())
+        .run();
+}