feat(api): update IWatch & mixin, boolean returns

thi-ng · Jan 28, 2018 · bddd5ce · bddd5ce
1 parent 55ba0e1
commit bddd5ce
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Showing 2 changed files with 11 additions and 3 deletions.
diff --git a/packages/api/src/api.ts b/packages/api/src/api.ts
@@ -289,7 +289,7 @@ export interface IStack<V, T> {
 export type Watch<T> = (id: string, oldState: T, newState: T) => void;
 
 export interface IWatch<T> {
-    addWatch(id: string, fn: Watch<T>);
-    removeWatch(id: string);
+    addWatch(id: string, fn: Watch<T>): boolean;
+    removeWatch(id: string): boolean;
     notifyWatches(oldState: T, newState: T);
 }
diff --git a/packages/api/src/mixins/iwatch.ts b/packages/api/src/mixins/iwatch.ts
@@ -4,11 +4,19 @@ import { mixin } from "../mixin";
 export const IWatch = mixin({
     addWatch(id: string, fn: (id: string, oldState: any, newState: any) => void) {
         this._watches = this._watches || {};
+        if (this._watches[id]) {
+            return false;
+        }
         this._watches[id] = fn;
+        return true;
     },
     removeWatch(id: string) {
         this._watches = this._watches || {};
-        delete this._watches[id];
+        if (this._watches[id]) {
+            delete this._watches[id];
+            return true;
+        }
+        return false;
     },
     notifyWatches(oldState: any, newState: any) {
         const w = (this._watches = this._watches || {}),