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    "---\n",
    "title: Generate Click command line options dynamically from class arguments\n",
    "date: 2022-10-26\n",
    "categories:\n",
    "  - python\n",
    "---"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "1e0d1df8-f595-4107-9e9f-68f143ba0fbd",
   "metadata": {},
   "source": [
    "In this application I need to use command line options to create class objects. In order not to repeat all class arguments in the [Click](https://click.palletsprojects.com) configuration, I created a simple function to dynamically create Click options. [See the source notebook of this page on Github](https://github.com/zonca/zonca.dev/blob/main/posts/2022-10-26-click-commandline-class-arguments.ipynb)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "287c0db4-a4a7-4d95-b39e-44ebb5d23a94",
   "metadata": {},
   "outputs": [],
   "source": [
    "import click\n",
    "import inspect"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "cbc46b54-d995-46ae-be01-07cc4dedd0a2",
   "metadata": {},
   "source": [
    "We have 2 classes, we want to pass the class name as argument to the command line tool and then all its arguments, for example:\n",
    "\n",
    "    createclass aclass --a somestring --b 6\n",
    "    \n",
    "We also use Python `typing` so we can pass that to Click."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "a511cc4c-01a7-4f6c-9c67-cc6bd01d1204",
   "metadata": {},
   "outputs": [],
   "source": [
    "class AClass:\n",
    "    def __init__(\n",
    "        self,\n",
    "        a: str,\n",
    "        b: int):\n",
    "        pass"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "04d8f528-b288-417e-89d9-0b518c1f5881",
   "metadata": {},
   "outputs": [],
   "source": [
    "class BClass:\n",
    "    def __init__(\n",
    "        self,\n",
    "        c: float,\n",
    "        d: bool,\n",
    "        under_score: str):\n",
    "        pass"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "31ebd324-d112-41df-a0a4-61e8042c2235",
   "metadata": {},
   "outputs": [],
   "source": [
    "def options_from_class(cls):\n",
    "    def decorator(f):\n",
    "        for par in inspect.signature(cls.__init__).parameters.values():\n",
    "            if par.name not in [\"self\"]:\n",
    "                click.option(\"--\" + par.name, required=True, type=par.annotation)(f)\n",
    "        return f\n",
    "    return decorator"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "c73d97ac-791b-4bd8-895c-3b31035ec455",
   "metadata": {},
   "outputs": [],
   "source": [
    "@click.group()\n",
    "def cli():\n",
    "    pass"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "e1303772-eb24-46ba-952e-3eb59f0f519e",
   "metadata": {},
   "outputs": [],
   "source": [
    "@cli.command()\n",
    "@options_from_class(AClass)\n",
    "def aclass(**kwargs):\n",
    "    click.echo('kwargs: {}'.format(kwargs))\n",
    "    ac = AClass(**kwargs)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "aef1bec9-7183-4abd-b486-f1760e178dd8",
   "metadata": {},
   "outputs": [],
   "source": [
    "@cli.command()\n",
    "@options_from_class(BClass)\n",
    "def bclass(**kwargs):\n",
    "    click.echo('kwargs: {}'.format(kwargs))\n",
    "    bc = BClass(**kwargs)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "5ba7946c-c95b-43aa-a40d-66b6ec96c325",
   "metadata": {},
   "outputs": [],
   "source": [
    "if __name__ == '__main__':\n",
    "    cli()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "9df86a13-a079-4826-9ff2-6961a73360d0",
   "metadata": {},
   "source": [
    "Convert the Notebook to a Python script with:\n",
    "\n",
    "    jupyter nbconvert click-commandline-class-arguments.ipynb --to python\n",
    "    \n",
    "Finally test at the command line:\n",
    "\n",
    "```\n",
    "$ python click-commandline-class-arguments.py aclass --help\n",
    "Usage: click-commandline-class-arguments.py aclass [OPTIONS]\n",
    "\n",
    "Options:\n",
    "  --b INTEGER  [required]\n",
    "  --a TEXT     [required]\n",
    "  --help       Show this message and exit.\n",
    "```\n",
    "\n",
    "```\n",
    "python click-commandline-class-arguments.py bclass --help\n",
    "Usage: click-commandline-class-arguments.py bclass [OPTIONS]\n",
    "\n",
    "Options:\n",
    "  --under_score TEXT  [required]\n",
    "  --d BOOLEAN         [required]\n",
    "  --c FLOAT           [required]\n",
    "  --help              Show this message and exit.\n",
    "```\n",
    "\n",
    "```\n",
    "$ python click-commandline-class-arguments.py bclass --d true --c 4.5 --under_score works\n",
    "kwargs: {'d': True, 'c': 4.5, 'under_score': 'works'}\n",
    "```"
   ]
  }
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