python3.12_demo.ipynb

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  {
   "cell_type": "markdown",
   "id": "c7a7e374-f7ff-4355-8313-6ad78a148260",
   "metadata": {},
   "source": [
    "# Python  3.12"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "51addbd8-958e-4e59-8778-197f11efd188",
   "metadata": {},
   "source": [
    "## Improved error messaging"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "ccfb41c1-8884-4107-9f14-ceaa122d5404",
   "metadata": {},
   "source": [
    "```python\n",
    "sys.version_info\n",
    "Traceback (most recent call last):\n",
    "  File \"<stdin>\", line 1, in <module>\n",
    "NameError: name 'sys' is not defined. Did you forget to import 'sys'?\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "ff19e26c-9895-4a3f-813f-6da4b9d17f21",
   "metadata": {},
   "source": [
    "```python\n",
    "import a.y.z from b.y.z\n",
    "Traceback (most recent call last):\n",
    "  File \"<stdin>\", line 1\n",
    "    import a.y.z from b.y.z\n",
    "    ^^^^^^^^^^^^^^^^^^^^^^^\n",
    "SyntaxError: Did you mean to use 'from ... import ...' instead?\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "e22cbf24-3a5b-485c-a4c4-299b37482261",
   "metadata": {},
   "source": [
    "## Immortal _immutable_ objects\n",
    "\n",
    "Mostly C API, not yet fully availalbe from Python code\n",
    "\n",
    "- https://peps.python.org/pep-0683/\n",
    "- https://engineering.fb.com/2023/08/15/developer-tools/immortal-objects-for-python-instagram-meta/\n",
    "\n",
    "This is an important building block towards a multi-core Python runtime. "
   ]
  },
  {
   "cell_type": "markdown",
   "id": "bb55385e-f05b-4c47-9c90-e1130c5b40b6",
   "metadata": {},
   "source": [
    "## Nested f-string"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "2f3e49e4-23e7-4110-84cf-3279a6fb8c66",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "literals: A; B; C\n",
      "literals: A; B; C\n"
     ]
    }
   ],
   "source": [
    "some_literals = [\"A\", \"B\", \"C\"]\n",
    "\n",
    "# before\n",
    "print(f\"literals: {'; '.join(some_literals)}\")\n",
    "\n",
    "# now\n",
    "print(f\"literals: {\"; \".join(some_literals)}\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "id": "efd61d72-c7df-4389-8311-363e2789e261",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'2'"
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "f\"{f\"{f\"{f\"{f\"{f\"{1+1}\"}\"}\"}\"}\"}\""
   ]
  },
  {
   "cell_type": "markdown",
   "id": "9217c03e-cc4b-4ab7-90a1-ecce99ed21f9",
   "metadata": {},
   "source": [
    "## `kwargs` unpacked to specify type"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "id": "48b36e32-7c94-4104-a00e-f3fde87d9aab",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'a': 'A', 'b': 'B'}\n"
     ]
    }
   ],
   "source": [
    "from typing import Unpack\n",
    "\n",
    "def print_all(**kwargs: Unpack[str]):\n",
    "    print(kwargs)\n",
    "\n",
    "print_all(a=\"A\", b=\"B\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "6b3adf96-9194-4051-9365-3c3b975d45aa",
   "metadata": {},
   "source": [
    "## `override` keyword"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "id": "b5702a4f-8062-41a4-adf3-66ab2c964faa",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'file'"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "from typing import override\n",
    "from typing import List\n",
    "\n",
    "\n",
    "class BaseHandler:\n",
    "    def load_snapshot(self) -> str: pass\n",
    "\n",
    "class DatabaseHandler(BaseHandler):\n",
    "    @override\n",
    "    def load_snapshot(self) -> str:\n",
    "        return \"db\"\n",
    "\n",
    "class FileHandler(BaseHandler):\n",
    "    @override\n",
    "    def load_snapshots(self) -> List[str]:  # Error reported by type checker\n",
    "        return \"file\""
   ]
  },
  {
   "cell_type": "markdown",
   "id": "6a0df028-3a31-4576-96fe-34d29d872729",
   "metadata": {},
   "source": [
    "## Type Parameter Syntax\n",
    "\n",
    "```python\n",
    "type Point[T] = tuple[T, T]\n",
    "type Constainer[T] = list[T] | set[T]\n",
    "\n",
    "def max[T](args: Iterable[T]) -> T:\n",
    "    ...\n",
    "\n",
    "class list[T]:\n",
    "    def __getitem__(self, index: int, /) -> T:\n",
    "        ...\n",
    "\n",
    "    def append(self, element: T) -> None:\n",
    "        ...\n",
    "```"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "6096f401-ce0f-4012-9c7e-0ac426c033cb",
   "metadata": {},
   "outputs": [],
   "source": []
  }
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