24_noglobal.ipynb

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  {
   "cell_type": "markdown",
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   "source": [
    "# Overview\n",
    "- noglobal デコレータを使う\n",
    "- jupyter notebook はglobal変数の汚染がすごいのでそれを解決したい。\n",
    "- twitterなどで少し議論があり、解決策が提案された\n",
    "    - https://twitter.com/raven_38_/status/1335500447168118784?s=20"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Function"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [],
   "source": [
    "import builtins\n",
    "import types\n",
    "\n",
    "def imports():\n",
    "    for name, val in globals().items():\n",
    "        # module imports\n",
    "        if isinstance(val, types.ModuleType):\n",
    "            yield name, val\n",
    "\n",
    "            # functions / callables\n",
    "        if hasattr(val, '__call__'):\n",
    "            yield name, val\n",
    "\n",
    "\n",
    "def noglobal(f):\n",
    "    '''\n",
    "    ref: https://gist.github.com/raven38/4e4c3c7a179283c441f575d6e375510c\n",
    "    '''\n",
    "    return types.FunctionType(f.__code__,\n",
    "                              dict(imports()),\n",
    "                              f.__name__,\n",
    "                              f.__defaults__,\n",
    "                              f.__closure__\n",
    "                              )"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Experiment"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<br>\n",
    "\n",
    "関数内でglobal変数が利用される例。  \n",
    "バグの温床になりやすい。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "112\n"
     ]
    }
   ],
   "source": [
    "hoge = 100\n",
    "def test01(a, b=10):\n",
    "    print(hoge + a + b)\n",
    "\n",
    "test01(2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "---> test01関数内でglobal変数が使われようとした時エラー表示になってほしい。  \n",
    "---> そこで、noglobalデコレータの出番。"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<br>\n",
    "\n",
    "使い方は簡単で、関数の上に `@noglobal` をつけたすだけ"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "ename": "NameError",
     "evalue": "name 'hoge' is not defined",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mNameError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-18-e9666e943f32>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      4\u001b[0m     \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mhoge\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0ma\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      5\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 6\u001b[0;31m \u001b[0mtest01\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m2\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;32m<ipython-input-18-e9666e943f32>\u001b[0m in \u001b[0;36mtest01\u001b[0;34m(a, b)\u001b[0m\n\u001b[1;32m      2\u001b[0m \u001b[0;34m@\u001b[0m\u001b[0mnoglobal\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      3\u001b[0m \u001b[0;32mdef\u001b[0m \u001b[0mtest01\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m10\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 4\u001b[0;31m     \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mhoge\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0ma\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m      5\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      6\u001b[0m \u001b[0mtest01\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m2\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mNameError\u001b[0m: name 'hoge' is not defined"
     ]
    }
   ],
   "source": [
    "hoge = 100\n",
    "@noglobal\n",
    "def test01(a, b=10):\n",
    "    print(hoge + a + b)\n",
    "\n",
    "test01(2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "---> ちゃんとエラー出た ;)"
   ]
  },
  {
   "cell_type": "raw",
   "metadata": {},
   "source": [
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "\n"
   ]
  }
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