Remove => and add finally blocks

src/lib.rs

@@ -1,6 +1,6 @@
 #[macro_export]
 macro_rules! system {
-    ($name:ident $pat:tt => $($rest:tt)* ) => {
+    ($name:ident $pat:tt { $($rest:tt)* } ) => {
         struct $name;
         impl<'a> specs::System<'a> for $name {
             type SystemData = args_to_systemdata!($pat);
@@ -11,6 +11,18 @@ macro_rules! system {
             }
         }
     };
+    ($name:ident $pat:tt { $($rest:tt)* } finally { $($finally:tt)* }) => {
+        struct $name;
+        impl<'a> specs::System<'a> for $name {
+            type SystemData = args_to_systemdata!($pat);
+            fn run(&mut self, args_to_pat!($pat): Self::SystemData) {
+                for args_to_pat!($pat) in args_to_join!($pat).join() {
+                    $($rest)*
+                }
+                $($finally)*
+            }
+        }
+    };
 }
 
 #[macro_export]
@@ -77,7 +89,15 @@ mod tests {
         type Storage = specs::VecStorage<Mov>;
     }
 
-    system! { Foo (_x: Mov, mut y: Pos,) =>
+    system! { Foo (_x: Mov, mut y: Pos) {
         y.x += 1;
     }
+    }
+
+    system! { Bar (_x: Mov, mut y: Pos) {
+        y.x += 1;
+    } finally {
+        println!("Done!");
+    }
+    }
 }