A very simple multi-party chat ipywidget.

ipychat_simple.ipynb

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  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# IPyChat"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "from ipywidgets import VBox, HBox, Textarea, Text, Layout, HTML"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "class IPyChat:\n",
    "    \"\"\"\n",
    "    A very simple multi-party chat ipywidget.\n",
    "    \n",
    "    At the moment this allows for chats between multiple instances of this\n",
    "    class running in the same process. The \"first\" instance becomes the main\n",
    "    participant, or host, or hub, and accepts other participants and manages\n",
    "    the communication between them in a star shape.\n",
    "    \n",
    "    Sadly, ipywidget.Textarea cannot be scrolled up automatically when it fills\n",
    "    up... :( see::\n",
    "    \n",
    "        https://github.com/jupyter-widgets/ipywidgets/issues/1815#issuecomment-480788783\n",
    "\n",
    "    Clearly, a better version could use some IPC via ZMQ where all participents\n",
    "    publish and subscribe to all without a centralized component needed (all\n",
    "    contributions welcome!).\n",
    "    \"\"\"\n",
    "    def __init__(self, server=None, name=None):\n",
    "        \"\"\"Create a chat instance.\n",
    "        \n",
    "        :param server: an object representing the central server to connect to\n",
    "            as a client\n",
    "        :param name: a string used to easily between different chat participants\n",
    "\n",
    "        When no ``server`` is specified this instnace becomes the chat host\n",
    "        and maintains a list of clients. Otherwise it becomes a client and\n",
    "        regards the given server as its host.\n",
    "        \"\"\"\n",
    "        self.name = name or id(self)\n",
    "        self.clients = []\n",
    "        self.server = server\n",
    "        if self.server:\n",
    "            self.server.add_client(self)        \n",
    "        self.build_ui()\n",
    "\n",
    "    def build_ui(self):\n",
    "        \"\"\"Build UI widgets to be rendered later.\"\"\"\n",
    "        title = f'<strong>IPyChat</strong> ({self.name})'\n",
    "        self.title_ht = HTML(title)\n",
    "        self.history_ta = Textarea(layout=Layout(height='100px'))\n",
    "        self.history_ta.disbaled = True\n",
    "        self.message_tx = Text(layout=Layout())\n",
    "        self.message_tx.on_submit(self.submitted_cb)\n",
    "        self.ui = VBox([\n",
    "            self.title_ht,\n",
    "            self.history_ta,\n",
    "            self.message_tx,\n",
    "        ])\n",
    "\n",
    "    def add_client(self, client):\n",
    "        \"\"\"As a server, add client to our list of clients.\"\"\"\n",
    "        if not self.server:\n",
    "            self.clients.append(client)\n",
    "        \n",
    "    def append_message(self, text, sender):\n",
    "        \"\"\"Append a message from some sender to our history widget.\"\"\"\n",
    "        if not self.server:\n",
    "            # we're a server/host\n",
    "            if sender == self:\n",
    "                self.history_ta.value += f'{sender.name}: {text}\\n'\n",
    "            else:\n",
    "                self.history_ta.value += f'{sender.name}: {text}\\n'\n",
    "            for client in self.clients:\n",
    "                if client != self:\n",
    "                    client.history_ta.value += f'{sender.name}: {text}\\n'                    \n",
    "        else:\n",
    "            # we're a client\n",
    "            self.server.append_message(text, self)\n",
    "                \n",
    "    def submitted_cb(self, sender):\n",
    "        \"When sender was submitted, pick text from input line and 'send' it.\"\n",
    "        text = self.message_tx.value\n",
    "        self.append_message(text, sender=self)\n",
    "        self.message_tx.value = ''"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "application/vnd.jupyter.widget-view+json": {
       "model_id": "227093aa1d9f4717b91b680cdd061a8c",
       "version_major": 2,
       "version_minor": 0
      },
      "text/plain": [
       "VBox(children=(HTML(value='<strong>IPyChat</strong> (Test)'), Textarea(value='', layout=Layout(height='100px')…"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "IPyChat(name='Test').ui"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [],
   "source": [
    "host = IPyChat(name='Admin')\n",
    "client1 = IPyChat(server=host, name='Alice')\n",
    "client2 = IPyChat(server=host, name='Bob')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "application/vnd.jupyter.widget-view+json": {
       "model_id": "397442546e694ac7a74b32ca966f1845",
       "version_major": 2,
       "version_minor": 0
      },
      "text/plain": [
       "HBox(children=(VBox(children=(HTML(value='<strong>IPyChat</strong> (Admin)'), Textarea(value='', layout=Layout…"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "HBox([host.ui, client1.ui, client2.ui])"
   ]
  }
 ],
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