Add support for awaitables

examples/commands.ipynb

@@ -40,7 +40,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "app.commands.list_commands()"
+    "sorted(app.commands.list_commands())"
    ]
   },
   {
@@ -158,6 +158,36 @@
     "out"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Await a command"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import asyncio\n",
+    "\n",
+    "from ipylab import JupyterFrontEnd\n",
+    "from ipywidgets import Output\n",
+    "\n",
+    "app = JupyterFrontEnd()\n",
+    "\n",
+    "\n",
+    "async def sequence():\n",
+    "    await app.ready()\n",
+    "    for i in range(4):\n",
+    "        result = await app.commands.execute('filebrowser:toggle-main')\n",
+    "        await asyncio.sleep(1)\n",
+    "\n",
+    "asyncio.create_task(sequence());"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -307,7 +337,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.8.1"
+   "version": "3.8.2"
   },
   "widgets": {
    "application/vnd.jupyter.widget-state+json": {

ipylab/awaitable.py

@@ -0,0 +1,26 @@
+# Copyright (c) Jeremy Tuloup.
+# Distributed under the terms of the Modified BSD License.
+
+import asyncio
+
+from uuid import uuid4
+
+
+class Awaitable:
+    def __init__(self, *args, **kwargs):
+        self._futures = {}
+
+    def _on_frontend_msg(self, _, content, buffers):
+        if content.get("event", "") == "future":
+            future_id = content.get("future_id")
+            result = content.get("result", None)
+            if future_id in self._futures:
+                self._futures[future_id].set_result(result)
+                del self._futures[future_id]
+
+    def register_future(self):
+        future_id = uuid4().hex
+        loop = asyncio.get_running_loop()
+        fut = loop.create_future()
+        self._futures[future_id] = fut
+        return future_id, fut

ipylab/commands.py

@@ -6,6 +6,7 @@
 from ipywidgets import CallbackDispatcher, Widget
 from traitlets import List, Unicode
 
+from .awaitable import Awaitable
 from ._frontend import module_name, module_version
 
 
@@ -33,7 +34,7 @@ def add_item(self, command_id, category, *, args=None, rank=None):
         )
 
 
-class CommandRegistry(Widget):
+class CommandRegistry(Widget, Awaitable):
     _model_name = Unicode("CommandRegistryModel").tag(sync=True)
     _model_module = Unicode(module_name).tag(sync=True)
     _model_module_version = Unicode(module_version).tag(sync=True)
@@ -49,10 +50,18 @@ def _on_frontend_msg(self, _, content, buffers):
         if content.get("event", "") == "execute":
             command_id = content.get("id")
             self._execute_callbacks[command_id]()
+        super()._on_frontend_msg(_, content, buffers)
 
     def execute(self, command_id, args=None):
         args = args or {}
-        self.send({"func": "execute", "payload": {"id": command_id, "args": args}})
+        fut_id, fut = super().register_future()
+        self.send(
+            {
+                "func": "execute",
+                "payload": {"id": command_id, "args": args, "future_id": fut_id},
+            }
+        )
+        return fut
 
     def list_commands(self):
         return self._commands

src/widgets/commands.ts

@@ -38,7 +38,7 @@ export class CommandRegistryModel extends WidgetModel {
   private _onMessage(msg: any) {
     switch (msg.func) {
       case 'execute':
-        this._execute(msg.payload);
+        void this._execute(msg.payload);
         break;
       case 'addCommand':
         void this._addCommand(msg.payload);
@@ -57,9 +57,11 @@ export class CommandRegistryModel extends WidgetModel {
     this.save_changes();
   }
 
-  private _execute(payload: any) {
-    const { id, args } = payload;
-    void this.commands.execute(id, args);
+  private async _execute(payload: any) {
+    const { id, args, future_id } = payload;
+    await this.commands.execute(id, args);
+    // TODO: send result back if possible?
+    this.send({ event: 'future', future_id }, {});
   }
 
   private async _addCommand(payload: any): Promise<void> {