module: sending global event requires sender module awareness

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

src/ecs/main.zig

@@ -122,6 +122,6 @@ test "example" {
 
     //-------------------------------------------------------------------------
     // Send events to modules
-    world.modules.send(.tick, .{});
+    world.mod.renderer.sendGlobal(.tick, .{});
     try world.dispatch();
 }

src/ecs/systems.zig

@@ -77,7 +77,7 @@ pub fn World(comptime mods: anytype) type {
                 pub inline fn sendGlobal(m: *@This(), comptime event_name: Modules.GlobalEvent, args: anytype) void {
                     const mod_ptr: *Mods = @alignCast(@fieldParentPtr(Mods, @tagName(module_tag), m));
                     const world = @fieldParentPtr(WorldT, "mod", mod_ptr);
-                    world.modules.send(event_name, args);
+                    world.modules.sendGlobal(module_tag, event_name, args);
                 }
 
                 pub fn dispatchNoError(m: *@This()) void {

src/engine.zig

@@ -25,6 +25,8 @@ pub const Engine = struct {
         .{ .local = .begin_pass, .handler = beginPass },
         .{ .local = .end_pass, .handler = endPass },
         .{ .local = .present, .handler = present },
+        .{ .global = .init, .handler = fn () void },
+        .{ .global = .deinit, .handler = fn () void },
         .{ .global = .tick, .handler = fn () void },
         .{ .global = .exit, .handler = fn () void },
     };
@@ -115,7 +117,7 @@ pub const App = struct {
 
     pub fn update(app: *@This()) !bool {
         // TODO: better dispatch implementation
-        app.world.modules.send(.tick, .{});
+        app.world.mod.engine.sendGlobal(.tick, .{});
         try app.world.dispatch(); // dispatch .tick
         try app.world.dispatch(); // dispatch any events produced by .tick
         return app.world.mod.engine.state.should_exit;

src/module.zig

@@ -89,7 +89,7 @@ pub fn Modules(comptime mods: anytype) type {
 
                 const Handler = switch (@typeInfo(@TypeOf(event.handler))) {
                     .Fn => @TypeOf(event.handler),
-                    .Type => |t| switch (@typeInfo(t)) {
+                    .Type => switch (@typeInfo(event.handler)) {
                         .Fn => event.handler,
                         else => unreachable,
                     },
@@ -106,10 +106,16 @@ pub fn Modules(comptime mods: anytype) type {
 
         /// Returns an args tuple representing the standard, uninjected, arguments which the given
         /// global event handler requires.
-        fn Args(event_name: GlobalEvent) type {
+        fn GlobalArgs(module_name: ModuleName(mods), event_name: GlobalEvent) type {
             inline for (modules) |M| {
                 _ = Module(M); // Validate the module
+                if (M.name != module_name) continue;
+                return GlobalArgsM(M, event_name);
+            }
+        }
 
+        pub fn GlobalArgsM(comptime M: type, event_name: GlobalEvent) type {
+            _ = Module(M); // Validate the module
             inline for (M.events) |event| {
                 const Ev = @TypeOf(event);
                 const name_tag = if (@hasField(Ev, "global")) event.global else continue;
@@ -129,16 +135,16 @@ pub fn Modules(comptime mods: anytype) type {
                 // `@Type(.{.Struct = .{ .is_tuple = false }})` instead of `.is_tuple = true`.
                 return UninjectedArgsTuple(TupleHACK, Handler);
             }
-            }
-            @compileError("No global event handler ." ++ @tagName(event_name) ++ " is defined in any module.");
+            @compileError("mach: module ." ++ @tagName(M.name) ++ " has no .global event handler for ." ++ @tagName(event_name));
         }
 
-        /// Send a global event
-        pub fn send(
+        /// Send a global event which the specified module defines
+        pub fn sendGlobal(
             m: *@This(),
             // TODO: is a variant of this function where event_name is not comptime known, but asserted to be a valid enum, useful?
+            comptime module_name: ModuleName(mods),
             comptime event_name: GlobalEvent,
-            args: Args(event_name),
+            args: GlobalArgs(module_name, event_name),
         ) void {
             // TODO: comptime safety/debugging
             m.sendInternal(null, @intFromEnum(event_name), args);
@@ -986,7 +992,7 @@ test "dispatch" {
     // global event handler declaration within a module. It is required that all global event handlers
     // of the same name have the same standard arguments, although they can start with different
     // injected arguments.
-    modules.send(.tick, .{});
+    modules.sendGlobal(.tick, .{});
     try testing.expect(usize, 0).eql(global.ticks);
     try modules.dispatch(.{&foo});
     try testing.expect(usize, 2).eql(global.ticks);
@@ -998,7 +1004,7 @@ test "dispatch" {
     // Global events which are not handled by anyone yet can be written as `pub const fooBar = fn() void;`
     // within a module, which allows pre-declaring that `fooBar` is a valid global event, and enables
     // its arguments to be inferred still like this:
-    modules.send(.frame_done, .{ .@"0" = 1337 });
+    modules.sendGlobal(.frame_done, .{ .@"0" = 1337 });
 
     // Local events
     modules.sendToModule(.engine_renderer, .update, .{});