lectures/01_1_done.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Пространство имен, области видимости"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Пространство имён (namespace)** — набор связей переменных с объектами.      \n",
    "**Область видимости (scope)** — место в коде, откуда доступно пространство имен."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Пространства имен:"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Built-in** - уровень интерпретатора, не требуется импорт."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "8\n"
     ]
    }
   ],
   "source": [
    "print(len('built-in'))  # например, встроенные функции"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Global** - уровень модуля (файл .py), доступ можно получить из любой функции, объявленной в данном модуле."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "global_var = 8"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "8"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "global_var"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Local** - переменные, которые создаются и используются внутри функции."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    "def my_func():\n",
    "    global_var = 2\n",
    "    local_var = 8\n",
    "    return global_var + local_var"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "10"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "my_func()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "8"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "global_var # значение не изменилось, потому что global_var внутри функции и снаружи - две разные переменные"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Инструкция global"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Если все-таки необходимо изменить глобальную переменную внутри локальной области видимости, используется инструкция **global**:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [],
   "source": [
    "def my_func2():\n",
    "    global global_var\n",
    "    global_var = 2\n",
    "    local_var = 8\n",
    "    return global_var + local_var"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "10"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "my_func2()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "scrolled": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "2"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "global_var # значение глобальной переменной изменилось"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Если переменной было присвоено значение внутри функции, обратиться к глобальному значению уже не получится!"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [],
   "source": [
    "global_var = 10\n",
    "def my_func3():\n",
    "    print(global_var)\n",
    "#     global_var = 5"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "10\n"
     ]
    }
   ],
   "source": [
    "my_func3()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Если не указаны инструкции, поиск переменных по пространствам имен происходит снизу вверх \n",
    "(от самого локального, к самому глобальному):   \n",
    "   +  **local** -> **global** -> **built-in**   \n",
    "![](http://www.buyukveri.co/wp-content/uploads/2018/03/python-scope.jpg)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Встроенные типы данных в Python"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "+ изменяемые *(list, dict, set)*\n",
    "+ неизменяемые *(int, float, string, tuple,bool)*"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [],
   "source": [
    "a_list = [1, 2, 3] #список\n",
    "a_tuple = (1, 2, 3) #кортеж"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "140262698213104"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "id('Hello ')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "140262698226800"
      ]
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "id('Hello ')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "140262698228016"
      ]
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "id('world')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "При добавлении нового элемента измененяется исходный объект:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 2, 3, 4]\n",
      "True\n"
     ]
    }
   ],
   "source": [
    "# добавим новый элемент - \n",
    "id_before = id(a_list)\n",
    "a_list.append(4)\n",
    "id_after = id(a_list)\n",
    "print(a_list)\n",
    "print(id_before == id_after) # один и тот же объект"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "При добавлении нового элемента создается новый объект, переменная перезаписывается: "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(1, 2, 3, 4)\n",
      "False\n"
     ]
    }
   ],
   "source": [
    "id_before = id(a_tuple)\n",
    "a_tuple += (4, ) # (эквивалентно a_tuple = a_tuple + (4, ))\n",
    "id_after = id(a_tuple)\n",
    "print(a_tuple)\n",
    "print(id_before == id_after) # переменная a_tuple теперь указывает на другой объект"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Еще кое-что о списках"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 2, 3, 4, 5]\n",
      "[1, 2, 3, 4, 5]\n",
      "[1, 2, 3, 4, 5]\n"
     ]
    }
   ],
   "source": [
    "original_list = [1, 2, 3]\n",
    "new_list = original_list\n",
    "new_list.append(4)\n",
    "\n",
    "newnew_list = new_list\n",
    "newnew_list.append(5)\n",
    "print(original_list)\n",
    "print(new_list)\n",
    "print(newnew_list)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Вопрос:** что выведет код ниже и почему так?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 2, 3, 4, 5]\n",
      "True\n"
     ]
    }
   ],
   "source": [
    "print(original_list)\n",
    "print(id(original_list) == id(new_list))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Как с этим бороться?**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {},
   "outputs": [],
   "source": [
    "import copy"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 2, 3, 4]\n",
      "[1, 2, 3]\n"
     ]
    }
   ],
   "source": [
    "original_list = [1, 2, 3]\n",
    "new_list = copy.copy(original_list)\n",
    "new_list.append(4)\n",
    "print(new_list)\n",
    "print(original_list)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Со вложенной структурой немного сложнее:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {},
   "outputs": [],
   "source": [
    "d = {\n",
    "    'a': [1, 2, 3],\n",
    "    \n",
    "    'b':  [4, 5, 6],\n",
    "}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "140262699457904"
      ]
     },
     "execution_count": 28,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "id(d['a'])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "metadata": {},
   "outputs": [],
   "source": [
    "d_copy = copy.copy(d)\n",
    "deep_copy = copy.deepcopy(d)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 30,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "(140262698247984, 140262698270144, 140262699151920)"
      ]
     },
     "execution_count": 30,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "id(d), id(d_copy), id(deep_copy)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "(140262699457904, 140262699457904, 140262699464816)"
      ]
     },
     "execution_count": 31,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "id(d['a']), id(d_copy['a']), id(deep_copy['a'])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Передача аргументов в функцию\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Префиксные звездочки в питоне"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Префиксные операторы - ставятся перед переменной:\n",
    "+ \\* - рапаковывает iterable в tuple/list    \n",
    "+ \\** - распаковывает словарь в словарь"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 32,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "[2, 3]\n"
     ]
    }
   ],
   "source": [
    "# * при присваивании значения\n",
    "variables = [1, 2, 3]\n",
    "first, *others = variables\n",
    "print(first)\n",
    "print(others)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 33,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "2 3\n"
     ]
    }
   ],
   "source": [
    "# * при вызове функции\n",
    "print(*others) # эквивавалентно print(others[0], others[1])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "8000\n"
     ]
    }
   ],
   "source": [
    "# ** при вызове функции \n",
    "def count_total(price, qty):\n",
    "    return price * qty\n",
    "arguments = {'price': 10, 'qty': 800}\n",
    "print(count_total(**arguments)) # эквивалентно count_total(price=10, qty=800)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 36,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "'price' is an invalid keyword argument for print()",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-36-8a6b4fd41974>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[0;31m# вопросик - как думаете, что выведет код?\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[0;34m**\u001b[0m\u001b[0marguments\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: 'price' is an invalid keyword argument for print()"
     ]
    }
   ],
   "source": [
    "# вопросик - как думаете, что выведет код?\n",
    "print(*arguments)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 38,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'day': '01', 'month': '01', 'year': '2022', 'price': '100', 'title': 'Book'}\n"
     ]
    }
   ],
   "source": [
    "# ** - объединение словарей\n",
    "date_info = {'day': '01', 'month': '01', 'year': '2022'}\n",
    "purchase_info = {'price': '100', 'title': 'Book'}\n",
    "all_info = {**date_info, **purchase_info}\n",
    "print(all_info)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Функции с позиционными аргументами"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 39,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(1, 2, 3)\n"
     ]
    },
    {
     "ename": "TypeError",
     "evalue": "func() takes 3 positional arguments but 5 were given",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-39-33dcaa6d84b1>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      3\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      4\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mfunc\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m2\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m3\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----> 5\u001b[0;31m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mfunc\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m2\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m3\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m4\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m5\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m)\u001b[0m \u001b[0;31m# падает, если дать больше аргументов, чем указано\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: func() takes 3 positional arguments but 5 were given"
     ]
    }
   ],
   "source": [
    "def func(x, y, z):\n",
    "    return x, y, z\n",
    "\n",
    "print(func(1, 2, 3))\n",
    "print(func(1, 2, 3, 4, 5)) # падает, если дать больше аргументов, чем указано"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Произвольное число позиционных аргументов (*args)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 41,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "6\n",
      "15\n"
     ]
    }
   ],
   "source": [
    "def s(*args):\n",
    "    args_sum = 0\n",
    "    for arg in args:\n",
    "        args_sum += arg\n",
    "    return args_sum\n",
    "\n",
    "print(s(1, 2, 3))\n",
    "print(s(1, 2, 3, 4, 5))\n",
    "#print(s())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Функции с именованными аргуметами"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 42,
   "metadata": {
    "scrolled": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(1, 2, 3)\n",
      "(1, 2, 3)\n",
      "(1, 2, 3)\n"
     ]
    }
   ],
   "source": [
    "def func(x, y, z):\n",
    "    return (x, y, z)\n",
    "print(func(1, 2, 3))  # передаем аргументы в том же порядке, в котором они перечислены в определении функции\n",
    "print(func(1, y=2, z=3))# можно передавать один или несколько аргументов по имени\n",
    "print(func(z=3, y=2, x=1)) # порядок именованных аргументов не важен"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 43,
   "metadata": {},
   "outputs": [
    {
     "ename": "SyntaxError",
     "evalue": "positional argument follows keyword argument (<ipython-input-43-056f61e52415>, line 1)",
     "output_type": "error",
     "traceback": [
      "\u001b[0;36m  File \u001b[0;32m\"<ipython-input-43-056f61e52415>\"\u001b[0;36m, line \u001b[0;32m1\u001b[0m\n\u001b[0;31m    print(func(z=3, 1, 2)) # НО! именованные аргументы всегда должны быть после позиционных\u001b[0m\n\u001b[0m                   ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m positional argument follows keyword argument\n"
     ]
    }
   ],
   "source": [
    "print(func(z=3, 1, 2)) # НО! именованные аргументы всегда должны быть после позиционных"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Необязательный аргумент (присваивается заданное по умолчанию значение)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(1, 2, 4)\n",
      "(1, 2, 3)\n"
     ]
    }
   ],
   "source": [
    "def func(x, y, z=3):\n",
    "    return (x, y, z)\n",
    "print(func(1, 2, 4))\n",
    "print(func(1, 2))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Произвольное число именованных аргументов (**kwargs)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Так же как мы можем передвать функции любое количество аргументов с помощью \\*args, \n",
    "мы можем передавать ей любые именованные аргументы с помощью \\*\\*kwargs.   \n",
    "\\*\\*kwargs представляется в питоне как словарь."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 46,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'a': 1, 'b': 2}\n",
      "1\n",
      "{'a': 1}\n",
      "1\n",
      "{'b': 2}\n"
     ]
    },
    {
     "ename": "KeyError",
     "evalue": "'a'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mKeyError\u001b[0m                                  Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-46-1c20398dd2ea>\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[0mfunc\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mb\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[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      5\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mfunc\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m1\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----> 6\u001b[0;31m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mfunc\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mb\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[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;32m<ipython-input-46-1c20398dd2ea>\u001b[0m in \u001b[0;36mfunc\u001b[0;34m(**kwargs)\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[0;32mdef\u001b[0m \u001b[0mfunc\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m**\u001b[0m\u001b[0mkwargs\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[1;32m      2\u001b[0m     \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mkwargs\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 3\u001b[0;31m     \u001b[0;32mreturn\u001b[0m \u001b[0mkwargs\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0;34m'a'\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      4\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mfunc\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mb\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[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      5\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mfunc\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m1\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;31mKeyError\u001b[0m: 'a'"
     ]
    }
   ],
   "source": [
    "def func(**kwargs):\n",
    "    return kwargs['a']\n",
    "print(func(a=1, b=2))\n",
    "print(func(a=1))\n",
    "print(func(b=2))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Почему изменяемый тип данных в параметре по умолчанию может быть не очень хорошей идеей?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 47,
   "metadata": {},
   "outputs": [],
   "source": [
    "def my_bad_func(num, a_list=[]):\n",
    "    a_list.append(num)\n",
    "    return a_list"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Что мы хотим:**\n",
    "   + если аргумент *a_list* не указан, то создается пустой список и *num* добавляется в него   \n",
    "\n",
    "**Что получается:**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 53,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[2]"
      ]
     },
     "execution_count": 53,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "my_bad_func(2) # желаемый результат [2]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 54,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[3]"
      ]
     },
     "execution_count": 54,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "my_bad_func(3) # желаемый результат [3]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 57,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[1, 2, 4]"
      ]
     },
     "execution_count": 57,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "my_bad_func(4, [1,2]) # желаемый результат [4]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Задание:**\n",
    "   + объяснить, почему так происходит\n",
    "   + исправить функцию, чтобы она работала так, как мы хотим "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 52,
   "metadata": {},
   "outputs": [],
   "source": [
    "def my_bad_func(num, a_list=None):\n",
    "    if a_list is None:\n",
    "        a_list = []\n",
    "    a_list.append(num)\n",
    "    return a_list"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Задание\n",
    "1. Напишите функцию, которая принимает в качестве аргументов неограниченное число строк и объединяет их в одну строку через пробел.\n",
    "3. Напишите функцию, которая принимает на вход другую функцию и все ее аргументы (позиционные или именованные) и печатает результат исполнения функции, а также сначала все позиционные аргументы, а потом все названия и значения именованных аргументов. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 61,
   "metadata": {},
   "outputs": [],
   "source": [
    "#1\n",
    "def glue_strings(*args):\n",
    "    return ' '.join(args)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 62,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'mm nn bb vv pp'"
      ]
     },
     "execution_count": 62,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "glue_strings('mm', 'nn', 'bb', 'vv', 'pp')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 63,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'a b'"
      ]
     },
     "execution_count": 63,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "glue_strings('a', 'b')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 64,
   "metadata": {},
   "outputs": [],
   "source": [
    "#2\n",
    "def remainder(number, divisor):\n",
    "    return number % divisor"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 66,
   "metadata": {},
   "outputs": [],
   "source": [
    "def trace_args_and_kwargs(func, *args, **kwargs):\n",
    "    print(func(*args, **kwargs))\n",
    "    print(args)\n",
    "    print(kwargs)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 67,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "2\n",
      "(7, 5)\n",
      "{}\n"
     ]
    }
   ],
   "source": [
    "trace_args_and_kwargs(remainder, 7, 5)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 69,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "5\n",
      "()\n",
      "{'number': 5, 'divisor': 7}\n"
     ]
    }
   ],
   "source": [
    "trace_args_and_kwargs(remainder, number=5, divisor=7)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 70,
   "metadata": {},
   "outputs": [],
   "source": [
    "for i in []:\n",
    "    print(i)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Дополнительные материалы"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "+ [Подробная статья про пространства имен](https://bytebaker.com/2008/07/30/python-namespaces/)\n",
    "+ [Статья про enclosing scope и замыкания](https://devpractice.ru/closures-in-python/)"
   ]
  }
 ],
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