By the power of macros, reduce the amount of syntax required to register components

src/main.rs

@@ -27,6 +27,17 @@ use player::*;
 pub use rect::Rect;
 use visibility_system::VisibilitySystem;
 
+/// Cut down on the amount of syntax to register components
+macro_rules! register {
+    // $gs is needed to get the scope at the usage point
+    // $Type is the Component type that is being registered
+    ($gs: ident, $( $Type: ty ),*,) => {
+        $(
+            $gs.ecs.register::<$Type>();
+        )*
+    }
+}
+
 pub const MAP_SIZE: usize = 80 * 50;
 
 #[derive(PartialEq, Copy, Clone)]
@@ -183,22 +194,25 @@ fn main() -> rltk::BError {
 
     let mut gs = State { ecs: World::new() };
 
-    gs.ecs.register::<Position>();
-    gs.ecs.register::<Renderable>();
-    gs.ecs.register::<Player>();
-    gs.ecs.register::<Viewshed>();
-    gs.ecs.register::<Monster>();
-    gs.ecs.register::<Name>();
-    gs.ecs.register::<BlocksTile>();
-    gs.ecs.register::<CombatStats>();
-    gs.ecs.register::<WantsToMelee>();
-    gs.ecs.register::<SufferDamage>();
-    gs.ecs.register::<Item>();
-    gs.ecs.register::<Potion>();
-    gs.ecs.register::<InBackpack>();
-    gs.ecs.register::<WantsToPickupItem>();
-    gs.ecs.register::<WantsToDrinkPotion>();
-    gs.ecs.register::<WantsToDropItem>();
+    register!(
+        gs,
+        Position,
+        Renderable,
+        Player,
+        Viewshed,
+        Monster,
+        Name,
+        BlocksTile,
+        CombatStats,
+        WantsToMelee,
+        SufferDamage,
+        Item,
+        Potion,
+        InBackpack,
+        WantsToPickupItem,
+        WantsToDrinkPotion,
+        WantsToDropItem,
+    );
 
     let map: Map = Map::new_map_rooms_and_corridors();
     let (player_x, player_y) = map.rooms[0].center();