positron widget buffers issue

positron-buffer-bug.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# This is broke:\n",
    "\n",
    "When I click the button, `1` should be appended to `msgs` file. Instead `0` is.\n",
    "\n",
    "(1 or 0 is the length of buffers list. In VSCode it is `1`, which is what I expect)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {
    "vscode": {
     "languageId": "python"
    }
   },
   "outputs": [],
   "source": [
    "import anywidget\n",
    "import traitlets\n",
    "\n",
    "\n",
    "class CounterWidget(anywidget.AnyWidget):\n",
    "    _esm = \"\"\"    \n",
    "    function render({ model, el }) {\n",
    "      let count = () => model.get(\"value\");\n",
    "      let btn = document.createElement(\"button\");\n",
    "      btn.classList.add(\"counter-button\");\n",
    "      btn.innerHTML = `count is ${count()}`;\n",
    "      btn.addEventListener(\"click\", () => {\n",
    "\n",
    "        model.set(\"value\", count() + 1);\n",
    "        model.save_changes();\n",
    "\n",
    "        let bytes = new TextEncoder().encode(\"Hello, world\");\n",
    "        model.send({message: \"Hello\"}, undefined, [new DataView(bytes.buffer)]);\n",
    "\n",
    "      });\n",
    "      model.on(\"change:value\", () => {\n",
    "        btn.innerHTML = `count is ${count()}`;\n",
    "      });\n",
    "      el.appendChild(btn);\n",
    "    }\n",
    "    export default { render };\n",
    "    \"\"\"\n",
    "    _css = \"\"\"\n",
    "    .counter-button {\n",
    "      background-image: linear-gradient(to right, #a1c4fd, #c2e9fb);\n",
    "      border: 0;\n",
    "      border-radius: 10px;\n",
    "      padding: 10px 50px;\n",
    "      color: white;\n",
    "    }\n",
    "    \"\"\"\n",
    "\n",
    "    def __init__(self, *args, **kwargs):\n",
    "        super().__init__(*args, **kwargs)\n",
    "        self.on_msg(self._handle_custom_msg)\n",
    "\n",
    "    def _handle_custom_msg(self, msg: dict, buffers: list):\n",
    "        with open(\"msgs\", \"a\") as file:\n",
    "            file.write(str(len(buffers)) + \"\\n\")\n",
    "\n",
    "    value = traitlets.Int(0).tag(sync=True)\n",
    "\n",
    "w = CounterWidget()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {
    "vscode": {
     "languageId": "python"
    }
   },
   "outputs": [
    {
     "data": {
      "application/vnd.jupyter.widget-view+json": {
       "model_id": "b9d4bc5c1ff341e58293790494ccd10b",
       "version_major": 2,
       "version_minor": 1
      },
      "text/plain": [
       "CounterWidget()"
      ]
     },
     "execution_count": null,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "w"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# This works: (Fixed issue #3974)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "vscode": {
     "languageId": "python"
    }
   },
   "outputs": [
    {
     "data": {
      "application/vnd.jupyter.widget-view+json": {
       "model_id": "5be5018e1a954578b5a44c2c90ec0125",
       "version_major": 2,
       "version_minor": 0
      },
      "text/plain": [
       "Image(value=b'\\x89PNG\\r\\n\\x1a\\n\\x00\\x00\\x00\\rIHDR\\x00\\x00\\x01Y\\x00\\x00\\x01c\\x08\\x06\\x00\\x00\\x00\\x97\\x13x\\x10\\x…"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "import ipywidgets\n",
    "with open('/home/declan/Downloads/visualization.png', 'rb') as f: image = f.read() # you'll need an actual image file\n",
    "display(ipywidgets.Image(value=image, format='png'))"
   ]
  }
 ],
 "metadata": {
  "language_info": {
   "name": "plaintext"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}