Simplify Subscribe()

cmd/templates/svelte/frontend/package.json.template

@@ -7,18 +7,25 @@
     "start": "sirv public"
   },
   "devDependencies": {
+    "@babel/core": "^7.11.6",
+    "@babel/plugin-syntax-dynamic-import": "^7.8.3",
+    "@babel/plugin-transform-runtime": "^7.11.5",
+    "@babel/preset-env": "^7.11.5",
     "@rollup/plugin-commonjs": "^14.0.0",
-	"@rollup/plugin-image": "^2.0.5",
+    "@rollup/plugin-image": "^2.0.5",
     "@rollup/plugin-node-resolve": "^8.0.0",
+    "core-js": "^3.6.5",
     "rollup": "^2.3.4",
+    "rollup-plugin-babel": "^4.4.0",
     "rollup-plugin-livereload": "^2.0.0",
+    "rollup-plugin-polyfill": "^3.0.0",
     "rollup-plugin-svelte": "^6.0.0",
     "rollup-plugin-terser": "^7.0.0",
     "svelte": "^3.0.0"
   },
   "dependencies": {
     "sirv-cli": "^1.0.0",
-	"@wailsapp/runtime": "^1.0.10",
+	  "@wailsapp/runtime": "^1.0.10",
-	"svelte-simple-modal": "^0.6.0"
+	  "svelte-simple-modal": "^0.6.0"
   }
 }

cmd/templates/svelte/frontend/rollup.config.js

@@ -4,6 +4,8 @@ import commonjs from '@rollup/plugin-commonjs';
 import livereload from 'rollup-plugin-livereload';
 import { terser } from 'rollup-plugin-terser';
 import image from '@rollup/plugin-image';
+import babel from 'rollup-plugin-babel';
+import polyfill from 'rollup-plugin-polyfill';
 
 const production = !process.env.ROLLUP_WATCH;
 
@@ -67,6 +69,37 @@ export default {
 		// browser on changes when not in production
 		!production && livereload('public'),
 
+		// Credit: https://blog.az.sg/posts/svelte-and-ie11/
+		babel({
+			extensions: [ '.js', '.jsx', '.es6', '.es', '.mjs', '.svelte', '.html' ],
+			runtimeHelpers: true,
+			exclude: [ 'node_modules/@babel/**', 'node_modules/core-js/**' ],
+			presets: [
+			  [
+				'@babel/preset-env',
+				{
+				  targets: '> 0.25%, not dead, IE 11',
+				  modules: false,
+				  spec: true, 
+				  useBuiltIns: 'usage',
+				  forceAllTransforms: true,
+				  corejs: 3,
+				},
+
+			  ]
+			],
+			plugins: [
+			  '@babel/plugin-syntax-dynamic-import',
+			  [
+				'@babel/plugin-transform-runtime',
+				{
+				  useESModules: true
+				}
+			  ]
+			]
+		  }),
+		  polyfill(['@webcomponents/webcomponentsjs']),
+
 		// If we're building for production (npm run build
 		// instead of npm run dev), minify
 		production && terser()

cmd/templates/vanilla/frontend/src/main.css

@@ -11,7 +11,7 @@ body {
   display: block;
   width:100%;
   text-align: center;
-  margin-top: 3rem;
+  margin-top: 1rem;
   font-size: 2rem;
 }
 
@@ -24,7 +24,7 @@ button {
 }
 
 .result {
-  margin-top: 3rem;
+  margin-top: 1rem;
   text-align: center;
   font-size: 2rem;
 }

cmd/templates/vanilla/frontend/src/main.js

@@ -36,7 +36,7 @@ function start() {
 		mystore.set(newValue);
 	};
 
-	mystore.subscribe( (state) => {
+	mystore.subscribe( function(state) {
 		document.getElementById('counter').innerText = state;
 	});
 	

cmd/version.go

@@ -1,4 +1,4 @@
 package cmd
 
 // Version - Wails version
-const Version = "v1.7.2-pre8"
+const Version = "v1.7.2-pre9"

runtime/store.go

@@ -45,7 +45,7 @@ type Store struct {
 	data                reflect.Value
 	dataType            reflect.Type
 	eventPrefix         string
-	callbacks           []func(interface{})
+	callbacks           []reflect.Value
 	runtime             *Runtime
 	notifySynchronously bool
 
@@ -143,10 +143,13 @@ func (s *Store) notify() {
 	// Execute callbacks
 	for _, callback := range s.callbacks {
 
+		// Build args
+		args := []reflect.Value{s.data}
+
 		if s.notifySynchronously {
-			callback(s.data)
+			callback.Call(args)
 		} else {
-			go callback(s.data)
+			go callback.Call(args)
 		}
 
 	}
@@ -184,11 +187,50 @@ func (s *Store) Set(data interface{}) error {
 	return nil
 }
 
+// callbackCheck ensures the given function to Subscribe() is
+// of the correct signature. Absolutely cannot wait for
+// generics to land rather than writing this nonsense.
+func (s *Store) callbackCheck(callback interface{}) error {
+
+	// Get type
+	callbackType := reflect.TypeOf(callback)
+
+	// Check callback is a function
+	if callbackType.Kind() != reflect.Func {
+		return fmt.Errorf("invalid value given to store.Subscribe(). Expected 'func(%s)'", s.dataType.String())
+	}
+
+	// Check input param
+	if callbackType.NumIn() != 1 {
+		return fmt.Errorf("invalid number of parameters given in callback function. Expected 1")
+	}
+
+	// Check input data type
+	if callbackType.In(0) != s.dataType {
+		return fmt.Errorf("invalid type for input parameter given in callback function. Expected %s, got %s", s.dataType.String(), callbackType.In(0))
+	}
+
+	// Check output param
+	if callbackType.NumOut() != 0 {
+		return fmt.Errorf("invalid number of return parameters given in callback function. Expected 0")
+	}
+
+	return nil
+}
+
 // Subscribe will subscribe to updates to the store by
 // providing a callback. Any updates to the store are sent
 // to the callback
-func (s *Store) Subscribe(callback func(interface{})) {
+func (s *Store) Subscribe(callback interface{}) {
-	s.callbacks = append(s.callbacks, callback)
+
+	err := s.callbackCheck(callback)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	callbackFunc := reflect.ValueOf(callback)
+
+	s.callbacks = append(s.callbacks, callbackFunc)
 }
 
 // updaterCheck ensures the given function to Update() is