Add a basic collection of env watchers.

Author: ericsnowcurrently

src/client/pythonEnvironments/base/watchers.ts

@@ -0,0 +1,23 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+import { Event } from 'vscode';
+import { IPythonEnvsWatcher, PythonEnvsChangedEvent, PythonEnvsWatcher } from './watcher';
+
+/**
+ * A wrapper around a set of watchers.
+ *
+ * If any of the wrapped watchers emits an event then this wrapper
+ * emits that event.
+ */
+export class PythonEnvsWatchers {
+    public readonly onChanged: Event<PythonEnvsChangedEvent>;
+    private watcher = new PythonEnvsWatcher();
+
+    constructor(watchers: ReadonlyArray<IPythonEnvsWatcher>) {
+        this.onChanged = this.watcher.onChanged;
+        watchers.forEach((w) => {
+            w.onChanged((e) => this.watcher.fire(e));
+        });
+    }
+}