{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Modules\n",
    "- module is a file containing Python definitions and statements intended for use in other Python programs\n",
    "- many Python modules come with built-in standard library"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Various ways to import names into the current namespace"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# import math module into the global namespace\n",
    "import math\n",
    "x = math.sqrt(100)\n",
    "print(x)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import random\n",
    "print(random.choice(list(range(1, 21))))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from random import choice"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(choice([1, 2, 3, 4]))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "help(math)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from math import * # Import all the identifiers from math\n",
    "print(sqrt(100))\n",
    "print(pi)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from math import radians, sin\n",
    "rad = radians(90)\n",
    "print(rad)\n",
    "print(sin(rad))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## names can be imported to local namespace"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def isUpper(letter):\n",
    "    import string # string name is local\n",
    "    return letter in string.ascii_uppercase"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "False\n"
     ]
    }
   ],
   "source": [
    "print(isUpper('a'))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "ename": "NameError",
     "evalue": "name 'string' 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-2-1f51304bf154>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[0;31m# can we use string module outside isUpper function?\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 2\u001b[0;31m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mstring\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mdigits\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mNameError\u001b[0m: name 'string' is not defined"
     ]
    }
   ],
   "source": [
    "# can we use string module outside isUpper function?\n",
    "print(string.digits)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## scope and lookup rules\n",
    "<p>The <strong>scope</strong> of an identifier is the region of program code in which the identifier can be accessed, or used.</p>\n",
    "Three important scopes in Python:\n",
    "- <strong> Local scope </strong> refers to identifiers declared within a function\n",
    "- <strong>Global scope</strong> refers to all the identifiers declared within the current module, or file\n",
    "- <strong>Built-in scope</strong> refers to all the identifiers built into Python -- those like <em>range</em> and <em>min</em> that are (almost) always available \n",
    "<p>Precedence rule:</p>\n",
    "<ol>\n",
    "    <li>innermost or local scope</li>\n",
    "    <li>global scope</li>\n",
    "    <li>built-in scope</li>\n",
    "</ol>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "def testLocalScope():\n",
    "    k = 5\n",
    "    for i in range(2):\n",
    "        for j in range(2):\n",
    "            if i == j:\n",
    "                k = 3\n",
    "                print('inside=',k)\n",
    "    print('outside=',k)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "inside= 3\n",
      "inside= 3\n",
      "outside= 3\n"
     ]
    }
   ],
   "source": [
    "test()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "ename": "NameError",
     "evalue": "name 'k' 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-21-eb2fa875d160>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mk\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mNameError\u001b[0m: name 'k' is not defined"
     ]
    }
   ],
   "source": [
    "print(k)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## User-defined modules\n",
    "#### use module1.py, module2.py inside modules folder to demonstrate user defined modules and importance of:\n",
    "```if __name__ == '__main__':\n",
    "        ...\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Packages\n",
    "- folder with module(s)\n",
    "- must define \\__init\\__.py empty module to initialize as package\n",
    "- can't import package itself (in a useful way) but only module(s) or identifiers in the modules\n",
    "- https://docs.python.org/3/tutorial/modules.html#packages"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## use fibos package to demostrate user-defined package"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "import fibos"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Help on package fibos:\n",
      "\n",
      "NAME\n",
      "    fibos\n",
      "\n",
      "PACKAGE CONTENTS\n",
      "    fibo\n",
      "\n",
      "FILE\n",
      "    /Volumes/Storage/CMU/Sp2019/CS0/thinkpythonnotebooks/fibos/__init__.py\n",
      "\n",
      "\n"
     ]
    }
   ],
   "source": [
    "help(fibos)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "ename": "AttributeError",
     "evalue": "module 'fibos' has no attribute 'fibo'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mAttributeError\u001b[0m                            Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-5-94afb397843e>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mfibos\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mfibo\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mfib\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[0m\n\u001b[0m",
      "\u001b[0;31mAttributeError\u001b[0m: module 'fibos' has no attribute 'fibo'"
     ]
    }
   ],
   "source": [
    "fibos.fibo.fib(10)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 1 1 2 3 5 8 13 21 34 \n"
     ]
    }
   ],
   "source": [
    "import fibos.fibo as f\n",
    "f.fib(10)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 1 1 2 3 5 8 13 21 34 \n"
     ]
    }
   ],
   "source": [
    "from fibos import fibo\n",
    "fibo.fib(10)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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