640_Nested_Functions.ipynb

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    "# Nested Functions\n",
    "\n",
    "In Python, almost everything can be \"nested\". A function is no different. We can put functions inside of functions. \n",
    "\n",
    "Due to **scoping** the nested functions can only run inside of the parent function. Or in other words, the nested fucntion cannot be executed from outside of the grouped functions. "
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    "def main_func():\n",
    "    print(\"Do a thing\")\n",
    "    \n",
    "    def second_func():\n",
    "        print(\"22222222222\")\n",
    "        \n",
    "    second_func()"
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      "Do a thing\n",
      "22222222222\n"
     ]
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    "main_func() "
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   "cell_type": "markdown",
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   "source": [
    "> **Note:** `main_func()` calls `second_func()` so broth print statements are executed. Try commenting out line 7 in the first cell and re-run the second cell. You should only see the one print statement."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [],
   "source": [
    "def parent(name=\"Henry\"):\n",
    "    print(f\"parent() was run with {name}\")\n",
    "    \n",
    "    def child():\n",
    "        return 159\n",
    "        \n",
    "    return child"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
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     "name": "stdout",
     "output_type": "stream",
     "text": [
      "parent() was run with Henry\n"
     ]
    }
   ],
   "source": [
    "var = parent()"
   ]
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   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
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     "data": {
      "text/plain": [
       "<function __main__.parent.<locals>.child()>"
      ]
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     "execution_count": 18,
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   "source": [
    "var"
   ]
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   "metadata": {},
   "source": [
    "> **Note:** `var` without the `()` is a pointer to the `child()` function. It will not execute unless you use `()` after it. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "159"
      ]
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
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   "source": [
    "var()"
   ]
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   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [],
   "source": [
    "def dog():\n",
    "    \n",
    "    def speak():\n",
    "        return \"Woof woof!\"\n",
    "    \n",
    "    total = speak()\n",
    "    \n",
    "    return speak"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [],
   "source": [
    "woof = dog()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<function __main__.dog.<locals>.speak()>"
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "woof"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Woof woof!'"
      ]
     },
     "execution_count": 23,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "woof()"
   ]
  }
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