Move binding logic into Variable

experiments/modern/src/maki-interpreter/Emitter.js

@@ -0,0 +1,44 @@
+class Emitter {
+  constructor() {
+    this._hooks = {};
+    // TODO: Rename this property
+    this._globalHooks = [];
+  }
+
+  listen(eventName, cb) {
+    if (this._hooks[eventName] == null) {
+      this._hooks[eventName] = [];
+    }
+    this._hooks[eventName].push(cb);
+    return () => {
+      this._hooks[eventName] = this._hooks[eventName].filter(
+        hookCb => hookCb !== cb
+      );
+    };
+  }
+
+  trigger(eventName, ...args) {
+    this._globalHooks.forEach(cb => cb(eventName, args));
+    if (this._hooks[eventName] == null) {
+      return;
+    }
+    this._hooks[eventName].forEach(cb => {
+      cb(...args);
+    });
+  }
+
+  listenToAll(cb) {
+    this._globalHooks.push(cb);
+    return () => {
+      this._globalHooks = this._globalHooks.filter(hookCb => hookCb !== cb);
+    };
+  }
+
+  dispose() {
+    // Note: This will cause any future trigger or hook to cause a runtime error.
+    this._hooks = null;
+    this._globalHooks = null;
+  }
+}
+
+module.exports = Emitter;

experiments/modern/src/maki-interpreter/interpreter.js

@@ -29,20 +29,13 @@ function main({ runtime, data, system, log }) {
       return interpret(binding.commandOffset, program, { log });
     };
 
-    // For now we only know how to handle System handlers.
-    if (binding.variableOffset === 0) {
-      const obj = program.variables[binding.variableOffset].getValue();
-      const method = program.methods[binding.methodOffset];
-      obj[method.name](handler);
-    } else {
-      console.warn(
-        "Not Implemented: Not binding to non-system events",
-        binding
-      );
-    }
+    const variable = program.variables[binding.variableOffset];
+
+    const method = program.methods[binding.methodOffset];
+    variable.hook(method.name, handler);
   });
 
-  system._start();
+  system.js_start();
 }
 
 module.exports = main;

experiments/modern/src/maki-interpreter/runtime/MakiObject.js

@@ -1,4 +1,22 @@
+const Emitter = require("../Emitter");
+
 class MakiObject {
+  constructor() {
+    this._emitter = new Emitter();
+  }
+
+  js_trigger(eventName, ...args) {
+    this._emitter.trigger(eventName, args);
+  }
+
+  js_listenToAll(cb) {
+    return this._emitter.listenToAll(cb);
+  }
+
+  js_dispose() {
+    this._emitter.dispose();
+  }
+
   /**
    * getClassName()
    *

experiments/modern/src/maki-interpreter/runtime/System.js

@@ -12,23 +12,10 @@ class System extends MakiObject {
     return "System";
   }
 
-  constructor() {
-    super();
-    this._onScriptLoadedCallbacks = [];
-    this._onSetXuiParamCallbacks = [];
+  js_start() {
+    this.js_trigger("onScriptLoaded");
   }
 
-  _start() {
-    this._onScriptLoadedCallbacks.forEach(cb => {
-      cb();
-    });
-  }
-  onScriptLoaded(cb) {
-    this._onScriptLoadedCallbacks.push(cb);
-  }
-  onSetXuiParam(cb) {
-    this._onSetXuiParamCallbacks.push(cb);
-  }
   getScriptGroup() {
     return new Group();
   }

experiments/modern/src/maki-interpreter/variable.js

@@ -1,7 +1,11 @@
+const Emitter = require("./Emitter");
+
 class Variable {
   constructor({ type, typeName }) {
     this.type = type;
     this.typeName = typeName;
+    this._emitter = new Emitter();
+    this._unsubscribeFromValue = null;
   }
 
   getValue() {
@@ -9,8 +13,27 @@ class Variable {
   }
 
   setValue(value) {
+    if (this._unsubscribeFromValue != null) {
+      this._unsubscribeFromValue();
+    }
+    if (this.typeName === "OBJECT") {
+      this._unsubscribeFromValue = value.js_listenToAll((eventName, args) => {
+        this._emitter.trigger(eventName, args);
+      });
+    }
     this._value = value;
   }
+
+  hook(eventName, cb) {
+    this._emitter.listen(eventName, cb);
+  }
+
+  dispose() {
+    if (this._unsubscribeFromValue) {
+      this._unsubscribeFromValue();
+    }
+    this._emitter.dispose();
+  }
 }
 
 module.exports = Variable;