astynax/metaprog_py.ipynb

## metaprog_py.ipynb
{
 "metadata": {
  "name": ""
 },
 "nbformat": 3,
 "nbformat_minor": 0,
 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "# \u041c\u0435\u0442\u0430\u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435 \u0432 Python"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "\u041f\u043e\u0441\u0442\u0430\u0440\u0430\u0435\u043c\u0441\u044f \u0440\u0430\u0441\u0441\u043c\u043e\u0442\u0440\u0435\u0442\u044c\n",
      "\n",
      "- function objects\n",
      "- \u0437\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u044f\n",
      "- \u0434\u0435\u043a\u043e\u0440\u0430\u0442\u043e\u0440\u044b\n",
      "- \u0434\u0435\u0441\u043a\u0440\u0438\u043f\u0442\u043e\u0440\u044b\n",
      "- \u0434\u0435\u043a\u043e\u0440\u0430\u0442\u043e\u0440\u0430\u0446\u0438\u044f \u043a\u043b\u0430\u0441\u0441\u043e\u0432\n",
      "- \u043c\u0435\u0442\u0430\u043a\u043b\u0430\u0441\u0441\u044b"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# \u0441\u043e\u0437\u0434\u0430\u0434\u0438\u043c \u043f\u0440\u043e\u0441\u0442\u0443\u044e \u0444\u0443\u043d\u043a\u0446\u0438\u044e\n",
      "def add(x, y):\n",
      "    \"\"\"\n",
      "    Add x to y\n",
      "    \"\"\"\n",
      "    return x + y"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 1
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "add.func_doc  # \u0434\u043e\u043a-\u0441\u0438\u0442\u043e\u043a\u0430 \u0434\u043e\u0441\u0442\u0443\u043f\u043d\u0430 \u0434\u043b\u044f \u0447\u0442\u0435\u043d\u0438\u044f/\u0437\u0430\u043f\u0438\u0441\u0438"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 2,
       "text": [
        "'\\n    Add x to y\\n    '"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "add.func_dict['adsd'] = 42 # \u0442\u0430\u043a\u0436\u0435 \u0444\u0443\u043d\u043a\u0446\u0438\u0438 \u043c\u043e\u0436\u043d\u043e \u0434\u043e\u0431\u0430\u0432\u0438\u0442\u044c \u0430\u0442\u0440\u0438\u0431\u0443\u0442\n",
      "add.adsd"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 3,
       "text": [
        "42"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print add.func_defaults # \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0439 \u043f\u043e-\u0443\u043c\u043e\u043b\u0447\u0430\u043d\u0438\u044e \u0432 \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u0435\u043d\u0438\u0438 \u0444\u0443\u043d\u0446\u0438\u0438 \u043d\u0435\u0442"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "None\n"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# \u043d\u043e \u043c\u044b \u043c\u043e\u0436\u0435\u043c \u0441\u043e\u0437\u0434\u0430\u0442\u044c \u043d\u043e\u0432\u0443\u044e \u0444\u0443\u043d\u043a\u0446\u0438\u044e \u043d\u0430 \u043e\u0441\u043d\u043e\u0432\u0435 \u0434\u0430\u043d\u043d\u043e\u0439,\n",
      "# \u0438 \u0434\u043e\u0431\u0430\u0432\u0438\u0442\u044c \u0435\u0439 \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u044f \u0430\u0440\u0433\u0443\u043c\u0435\u043d\u0442\u043e\u0432 \u043f\u043e-\u0443\u043c\u043e\u043b\u0447\u0430\u043d\u0438\u044e\n",
      "import new\n",
      "add_w_def = new.function(\n",
      "    add.func_code, add.func_globals, 'add2', (0, 1))\n",
      "print add_w_def(), add_w_def(41)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1 42\n"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## \u0417\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u044f"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "a = 2\n",
      "def f(b):\n",
      "    return a + b\n",
      "a = 10\n",
      "print f(0)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "10\n"
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "f.func_globals['a']\n",
      "# \u043f\u0435\u0440\u0435\u043c\u0435\u043d\u043d\u0430\u044f \"a\" \u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u0433\u043b\u043e\u0431\u0430\u043b\u044c\u043d\u043e\u0439, \u0434\u043b\u044f \u0444-\u0446\u0438\u0438 f,\n",
      "# \u0442.\u043a. \u0438 \"a\" \u0438 \"f\" \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u0435\u043d\u044b \u0432 \u0442\u043e\u043c \u0436\u0435 \u0444\u0440\u0435\u0439\u043c\u0435 \u0441\u0442\u0435\u043a\u0430,\n",
      "# \u0432 \u043a\u043e\u0442\u043e\u0440\u043e\u043c \u0444\u0443\u043d\u043a\u0446\u0438\u044f \u0438 \u0432\u044b\u0437\u044b\u0432\u0430\u0435\u0442\u0441\u044f"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 7,
       "text": [
        "10"
       ]
      }
     ],
     "prompt_number": 7
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def make_f(a):\n",
      "    def f(b):\n",
      "        return a + b\n",
      "    return f"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 8
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "f1 = make_f(42)\n",
      "print f1(100), f1(10)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "142 52\n"
       ]
      }
     ],
     "prompt_number": 9
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print f1.func_closure\n",
      "print f1.func_closure[0].cell_contents # \u0432\u043d\u0443\u0442\u0440\u0438 \u044f\u0447\u0435\u0439\u043a\u0438 \u043a\u043e\u0440\u0442\u0435\u0436\u0430 \u0437\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u0439 - \u0437\u0430\u043c\u043a\u043d\u0443\u0442\u043e\u0435 \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0435"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "(<cell at 0x931d9ec: int object at 0x8b3df04>,)\n",
        "42\n"
       ]
      }
     ],
     "prompt_number": 10
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "f1.func_globals['a'] = 4564 # \u0434\u043e\u0431\u0430\u0432\u043b\u0435\u043d\u0438\u0435 \u0433\u043b\u043e\u0431\u0430\u043b\u044c\u043d\u043e\u0439 \u043f\u0435\u0440\u0435\u043c\u0435\u043d\u043d\u043e\u0439 \u043d\u0435 \u0432\u043b\u0438\u044f\u0435\u0442 \u043d\u0430 \u0437\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u0435\n",
      "f1(1)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 11,
       "text": [
        "43"
       ]
      }
     ],
     "prompt_number": 11
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# \u0445\u0440\u0430\u043d\u0435\u043d\u0438\u0435 \u0441\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u044f \u0432 \u0437\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u0438\n",
      "def make_logger():\n",
      "    log = []\n",
      "    def write_to_log(s):\n",
      "        log.append(s)\n",
      "    def read_log():\n",
      "        return log[:]\n",
      "    return {'write': write_to_log, 'read': read_log}"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 12
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "log = make_logger()\n",
      "log['write']('asdad')\n",
      "log['write']('asdqweqw')\n",
      "log['write'].func_closure[0].cell_contents"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 13,
       "text": [
        "['asdad', 'asdqweqw']"
       ]
      }
     ],
     "prompt_number": 13
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print log['read']()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "['asdad', 'asdqweqw']\n"
       ]
      }
     ],
     "prompt_number": 14
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u044f \"\u043f\u0440\u0438\u0432\u0430\u0442\u043d\u043e\u0441\u0442\u0438\" \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0439\n",
      "def make_class():\n",
      "    const = 42\n",
      "    class C(object):\n",
      "        def get(self):\n",
      "            return const\n",
      "    return C\n",
      "C = make_class()\n",
      "C().get()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 15,
       "text": [
        "42"
       ]
      }
     ],
     "prompt_number": 15
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## \u0414\u0435\u043a\u043e\u0440\u0430\u0442\u043e\u0440\u044b"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def dec(msg):\n",
      "    def wrapper(fn):\n",
      "        def inner(*args, **kwargs):\n",
      "            print msg\n",
      "            return fn(*args, **kwargs)\n",
      "        inner.func_doc = fn.func_doc\n",
      "        inner.func_name = fn.func_name\n",
      "        return inner\n",
      "    return wrapper"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 16
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "@dec(\"hello!\")\n",
      "def f(a):\n",
      "    return a + 1\n",
      "f(10)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "hello!\n"
       ]
      },
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 17,
       "text": [
        "11"
       ]
      }
     ],
     "prompt_number": 17
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## \u0414\u0435\u0441\u043a\u0440\u0438\u043f\u0442\u043e\u0440\u044b"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "class ROValue(object):\n",
      "    \n",
      "    def __init__(self, att_name):\n",
      "        self._att_name = att_name\n",
      "    \n",
      "    def __get__(self, inst, cls):\n",
      "        assert inst, \"Thist is instance attr\"\n",
      "        return getattr(inst, self._att_name)\n",
      "    \n",
      "    def __set__(self, inst, value):\n",
      "        raise TypeError(\"Readonly!\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 18
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "class Our(object):\n",
      "    _a = 42\n",
      "    a = ROValue('_a')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 19
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "Our().a"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 20,
       "text": [
        "42"
       ]
      }
     ],
     "prompt_number": 20
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "our = Our()\n",
      "our.a = 43"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "ename": "TypeError",
       "evalue": "Readonly!",
       "output_type": "pyerr",
       "traceback": [
        "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[1;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
        "\u001b[1;32m<ipython-input-21-ba09226d8ba8>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m      1\u001b[0m \u001b[0mour\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mOur\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 2\u001b[1;33m \u001b[0mour\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0ma\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;36m43\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
        "\u001b[1;32m<ipython-input-18-bbdf8e7bb55f>\u001b[0m in \u001b[0;36m__set__\u001b[1;34m(self, inst, value)\u001b[0m\n\u001b[0;32m      9\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m     10\u001b[0m     \u001b[1;32mdef\u001b[0m \u001b[0m__set__\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mself\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0minst\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mvalue\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m---> 11\u001b[1;33m         \u001b[1;32mraise\u001b[0m \u001b[0mTypeError\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;34m\"Readonly!\"\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
        "\u001b[1;31mTypeError\u001b[0m: Readonly!"
       ]
      }
     ],
     "prompt_number": 21
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "class Cached(object):\n",
      "    \n",
      "    def __init__(self, att_name, generate):\n",
      "        self._att_name = att_name\n",
      "        self._generate = generate\n",
      "    \n",
      "    def __get__(self, inst, cls):\n",
      "        assert inst, \"Thist is instance attr\"\n",
      "        if hasattr(inst, self._att_name):\n",
      "            return getattr(inst, self._att_name)\n",
      "        val = self._generate(inst)\n",
      "        setattr(inst, self._att_name, val)\n",
      "        return val\n",
      "    \n",
      "    def __set__(self, inst, value):\n",
      "        raise TypeError(\"Readonly!\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 22
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def very_slow(obj):\n",
      "    print \"Veryy slooow!\"\n",
      "    return 1\n",
      "\n",
      "class Our(object):\n",
      "    big_int = Cached('_big_int_cache', very_slow)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 23
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "o = Our()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 24
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print o.big_int # \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0435 \u0432\u044b\u0447\u0438\u0441\u043b\u0438\u0442\u0441\u044f \u0442\u043e\u043b\u044c\u043a\u043e \u0442\u0443\u0442\n",
      "print o.big_int"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Veryy slooow!\n",
        "1\n",
        "1\n"
       ]
      }
     ],
     "prompt_number": 25
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "class TypedAttr(object):\n",
      "    def __init__(self, attr_name, value_name, typ):\n",
      "        self._attr_name = attr_name\n",
      "        self._value_name = value_name\n",
      "        self._type = typ\n",
      "\n",
      "    def __get__(self, inst, cls):\n",
      "        assert inst\n",
      "        return inst.__dict__[self._value_name]\n",
      "    \n",
      "    def __set__(self, inst, value):\n",
      "        assert inst\n",
      "        if not isinstance(value, self._type):\n",
      "            raise TypeError(\n",
      "                'Value of attr \"%s\" must be %s' % (\n",
      "                    self._attr_name, self._type\n",
      "                ))\n",
      "        inst.__dict__[self._value_name] = value"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 26
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "class Point(object):\n",
      "    x = TypedAttr('x', '_x', int)\n",
      "    y = TypedAttr('y', '_y', int)\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 27
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "p = Point()\n",
      "p.x = 10\n",
      "p.y = \"asdasd\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "ename": "TypeError",
       "evalue": "Value of attr \"y\" must be <type 'int'>",
       "output_type": "pyerr",
       "traceback": [
        "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[1;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
        "\u001b[1;32m<ipython-input-28-ca4e8f3ca389>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m      1\u001b[0m \u001b[0mp\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mPoint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      2\u001b[0m \u001b[0mp\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mx\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;36m10\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 3\u001b[1;33m \u001b[0mp\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0my\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;34m\"asdasd\"\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
        "\u001b[1;32m<ipython-input-26-d9795cd9bdc5>\u001b[0m in \u001b[0;36m__set__\u001b[1;34m(self, inst, value)\u001b[0m\n\u001b[0;32m     14\u001b[0m             raise TypeError(\n\u001b[0;32m     15\u001b[0m                 'Value of attr \"%s\" must be %s' % (\n\u001b[1;32m---> 16\u001b[1;33m                     \u001b[0mself\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0m_attr_name\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mself\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0m_type\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m     17\u001b[0m                 ))\n\u001b[0;32m     18\u001b[0m         \u001b[0minst\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0m__dict__\u001b[0m\u001b[1;33m[\u001b[0m\u001b[0mself\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0m_value_name\u001b[0m\u001b[1;33m]\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mvalue\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
        "\u001b[1;31mTypeError\u001b[0m: Value of attr \"y\" must be <type 'int'>"
       ]
      }
     ],
     "prompt_number": 28
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## \u0414\u0435\u043a\u043e\u0440\u0430\u0446\u0438\u044f \u043a\u043b\u0430\u0441\u0441\u043e\u0432"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def serializable(cls):\n",
      "    cls.to_str = lambda self: str(self)\n",
      "    return cls"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 29
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "@serializable\n",
      "class C(object):\n",
      "    pass"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 30
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "C().to_str()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 31,
       "text": [
        "'<__main__.C object at 0x93a68ac>'"
       ]
      }
     ],
     "prompt_number": 31
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## \u041c\u0435\u0442\u0430\u043a\u043b\u0430\u0441\u0441\u044b"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def with_defaults(name, bases, dic):\n",
      "    orig = dic['__init__']\n",
      "    dic['__init__'] = new.function(\n",
      "        orig.func_code,\n",
      "        orig.func_globals,\n",
      "        orig.func_name,\n",
      "        dic.get('_init_defaults', ())\n",
      "    )\n",
      "    return type(name, bases, dic)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 32
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "class C(object):\n",
      "    __metaclass__ = with_defaults\n",
      "    \n",
      "    _init_defaults = (5, 6)\n",
      "    \n",
      "    def __init__(self, a, b):\n",
      "        print \"instantiated with args:\", a, b"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 33
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "c = C()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "instantiated with args: 5 6\n"
       ]
      }
     ],
     "prompt_number": 34
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "class D(C):\n",
      "    _init_defaults = (42, 24)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 35
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "d = D()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "instantiated with args: 5 6\n"
       ]
      }
     ],
     "prompt_number": 33
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "\u041f\u0435\u0440\u0435\u043a\u0440\u044b\u0442\u0438\u0435 ```_init_defaults``` \u043d\u0438\u0447\u0435\u0433\u043e \u043d\u0435 \u0434\u0430\u043b\u043e, \u0442.\u043a \u043c\u0435\u0442\u0430\u043a\u043b\u0430\u0441\u0441 \u0443\u0436\u0435 \u043e\u0442\u0440\u0430\u0431\u043e\u0442\u0430\u043b \u043e\u0434\u043d\u0430\u0436\u0434\u044b (\u0433\u0435\u043d\u0435\u0440\u0438\u0440\u0443\u044f ```\u0421```)"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "*\u0441\u0441\u044b\u043b\u043a\u0438 \u043d\u0430 \u0442\u0435\u043c\u0443*\n",
      "\n",
      "- [Python 3 Metaprogramming](https://www.youtube.com/watch?v=sPiWg5jSoZI)\n",
      "- [Python Metaprogramming for Mad Scientists and Evil Geniuses](https://www.youtube.com/watch?v=Adr_QuDZxuM)"
     ]
    }
   ],
   "metadata": {}
  }
 ]
}
	{
	"metadata": {
	"name": ""
	},
	"nbformat": 3,
	"nbformat_minor": 0,
	"worksheets": [
	{
	"cells": [
	{
	"cell_type": "markdown",
	"metadata": {},
	"source": [
	"# \u041c\u0435\u0442\u0430\u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435 \u0432 Python"
	]
	},
	{
	"cell_type": "markdown",
	"metadata": {},
	"source": [
	"\u041f\u043e\u0441\u0442\u0430\u0440\u0430\u0435\u043c\u0441\u044f \u0440\u0430\u0441\u0441\u043c\u043e\u0442\u0440\u0435\u0442\u044c\n",
	"\n",
	"- function objects\n",
	"- \u0437\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u044f\n",
	"- \u0434\u0435\u043a\u043e\u0440\u0430\u0442\u043e\u0440\u044b\n",
	"- \u0434\u0435\u0441\u043a\u0440\u0438\u043f\u0442\u043e\u0440\u044b\n",
	"- \u0434\u0435\u043a\u043e\u0440\u0430\u0442\u043e\u0440\u0430\u0446\u0438\u044f \u043a\u043b\u0430\u0441\u0441\u043e\u0432\n",
	"- \u043c\u0435\u0442\u0430\u043a\u043b\u0430\u0441\u0441\u044b"
	]
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"# \u0441\u043e\u0437\u0434\u0430\u0434\u0438\u043c \u043f\u0440\u043e\u0441\u0442\u0443\u044e \u0444\u0443\u043d\u043a\u0446\u0438\u044e\n",
	"def add(x, y):\n",
	" \"\"\"\n",
	" Add x to y\n",
	" \"\"\"\n",
	" return x + y"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 1
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"add.func_doc # \u0434\u043e\u043a-\u0441\u0438\u0442\u043e\u043a\u0430 \u0434\u043e\u0441\u0442\u0443\u043f\u043d\u0430 \u0434\u043b\u044f \u0447\u0442\u0435\u043d\u0438\u044f/\u0437\u0430\u043f\u0438\u0441\u0438"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"metadata": {},
	"output_type": "pyout",
	"prompt_number": 2,
	"text": [
	"'\\n Add x to y\\n '"
	]
	}
	],
	"prompt_number": 2
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"add.func_dict['adsd'] = 42 # \u0442\u0430\u043a\u0436\u0435 \u0444\u0443\u043d\u043a\u0446\u0438\u0438 \u043c\u043e\u0436\u043d\u043e \u0434\u043e\u0431\u0430\u0432\u0438\u0442\u044c \u0430\u0442\u0440\u0438\u0431\u0443\u0442\n",
	"add.adsd"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"metadata": {},
	"output_type": "pyout",
	"prompt_number": 3,
	"text": [
	"42"
	]
	}
	],
	"prompt_number": 3
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"print add.func_defaults # \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0439 \u043f\u043e-\u0443\u043c\u043e\u043b\u0447\u0430\u043d\u0438\u044e \u0432 \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u0435\u043d\u0438\u0438 \u0444\u0443\u043d\u0446\u0438\u0438 \u043d\u0435\u0442"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"output_type": "stream",
	"stream": "stdout",
	"text": [
	"None\n"
	]
	}
	],
	"prompt_number": 4
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"# \u043d\u043e \u043c\u044b \u043c\u043e\u0436\u0435\u043c \u0441\u043e\u0437\u0434\u0430\u0442\u044c \u043d\u043e\u0432\u0443\u044e \u0444\u0443\u043d\u043a\u0446\u0438\u044e \u043d\u0430 \u043e\u0441\u043d\u043e\u0432\u0435 \u0434\u0430\u043d\u043d\u043e\u0439,\n",
	"# \u0438 \u0434\u043e\u0431\u0430\u0432\u0438\u0442\u044c \u0435\u0439 \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u044f \u0430\u0440\u0433\u0443\u043c\u0435\u043d\u0442\u043e\u0432 \u043f\u043e-\u0443\u043c\u043e\u043b\u0447\u0430\u043d\u0438\u044e\n",
	"import new\n",
	"add_w_def = new.function(\n",
	" add.func_code, add.func_globals, 'add2', (0, 1))\n",
	"print add_w_def(), add_w_def(41)"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"output_type": "stream",
	"stream": "stdout",
	"text": [
	"1 42\n"
	]
	}
	],
	"prompt_number": 5
	},
	{
	"cell_type": "markdown",
	"metadata": {},
	"source": [
	"## \u0417\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u044f"
	]
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"a = 2\n",
	"def f(b):\n",
	" return a + b\n",
	"a = 10\n",
	"print f(0)"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"output_type": "stream",
	"stream": "stdout",
	"text": [
	"10\n"
	]
	}
	],
	"prompt_number": 6
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"f.func_globals['a']\n",
	"# \u043f\u0435\u0440\u0435\u043c\u0435\u043d\u043d\u0430\u044f \"a\" \u044f\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u0433\u043b\u043e\u0431\u0430\u043b\u044c\u043d\u043e\u0439, \u0434\u043b\u044f \u0444-\u0446\u0438\u0438 f,\n",
	"# \u0442.\u043a. \u0438 \"a\" \u0438 \"f\" \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u0435\u043d\u044b \u0432 \u0442\u043e\u043c \u0436\u0435 \u0444\u0440\u0435\u0439\u043c\u0435 \u0441\u0442\u0435\u043a\u0430,\n",
	"# \u0432 \u043a\u043e\u0442\u043e\u0440\u043e\u043c \u0444\u0443\u043d\u043a\u0446\u0438\u044f \u0438 \u0432\u044b\u0437\u044b\u0432\u0430\u0435\u0442\u0441\u044f"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"metadata": {},
	"output_type": "pyout",
	"prompt_number": 7,
	"text": [
	"10"
	]
	}
	],
	"prompt_number": 7
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"def make_f(a):\n",
	" def f(b):\n",
	" return a + b\n",
	" return f"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 8
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"f1 = make_f(42)\n",
	"print f1(100), f1(10)"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"output_type": "stream",
	"stream": "stdout",
	"text": [
	"142 52\n"
	]
	}
	],
	"prompt_number": 9
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"print f1.func_closure\n",
	"print f1.func_closure[0].cell_contents # \u0432\u043d\u0443\u0442\u0440\u0438 \u044f\u0447\u0435\u0439\u043a\u0438 \u043a\u043e\u0440\u0442\u0435\u0436\u0430 \u0437\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u0439 - \u0437\u0430\u043c\u043a\u043d\u0443\u0442\u043e\u0435 \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0435"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"output_type": "stream",
	"stream": "stdout",
	"text": [
	"(<cell at 0x931d9ec: int object at 0x8b3df04>,)\n",
	"42\n"
	]
	}
	],
	"prompt_number": 10
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"f1.func_globals['a'] = 4564 # \u0434\u043e\u0431\u0430\u0432\u043b\u0435\u043d\u0438\u0435 \u0433\u043b\u043e\u0431\u0430\u043b\u044c\u043d\u043e\u0439 \u043f\u0435\u0440\u0435\u043c\u0435\u043d\u043d\u043e\u0439 \u043d\u0435 \u0432\u043b\u0438\u044f\u0435\u0442 \u043d\u0430 \u0437\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u0435\n",
	"f1(1)"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"metadata": {},
	"output_type": "pyout",
	"prompt_number": 11,
	"text": [
	"43"
	]
	}
	],
	"prompt_number": 11
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"# \u0445\u0440\u0430\u043d\u0435\u043d\u0438\u0435 \u0441\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u044f \u0432 \u0437\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u0438\n",
	"def make_logger():\n",
	" log = []\n",
	" def write_to_log(s):\n",
	" log.append(s)\n",
	" def read_log():\n",
	" return log[:]\n",
	" return {'write': write_to_log, 'read': read_log}"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 12
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"log = make_logger()\n",
	"log['write']('asdad')\n",
	"log['write']('asdqweqw')\n",
	"log['write'].func_closure[0].cell_contents"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"metadata": {},
	"output_type": "pyout",
	"prompt_number": 13,
	"text": [
	"['asdad', 'asdqweqw']"
	]
	}
	],
	"prompt_number": 13
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"print log['read']()"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"output_type": "stream",
	"stream": "stdout",
	"text": [
	"['asdad', 'asdqweqw']\n"
	]
	}
	],
	"prompt_number": 14
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"# \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u044f \"\u043f\u0440\u0438\u0432\u0430\u0442\u043d\u043e\u0441\u0442\u0438\" \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0439\n",
	"def make_class():\n",
	" const = 42\n",
	" class C(object):\n",
	" def get(self):\n",
	" return const\n",
	" return C\n",
	"C = make_class()\n",
	"C().get()"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"metadata": {},
	"output_type": "pyout",
	"prompt_number": 15,
	"text": [
	"42"
	]
	}
	],
	"prompt_number": 15
	},
	{
	"cell_type": "markdown",
	"metadata": {},
	"source": [
	"## \u0414\u0435\u043a\u043e\u0440\u0430\u0442\u043e\u0440\u044b"
	]
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"def dec(msg):\n",
	" def wrapper(fn):\n",
	" def inner(args, *kwargs):\n",
	" print msg\n",
	" return fn(args, *kwargs)\n",
	" inner.func_doc = fn.func_doc\n",
	" inner.func_name = fn.func_name\n",
	" return inner\n",
	" return wrapper"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 16
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"@dec(\"hello!\")\n",
	"def f(a):\n",
	" return a + 1\n",
	"f(10)"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"output_type": "stream",
	"stream": "stdout",
	"text": [
	"hello!\n"
	]
	},
	{
	"metadata": {},
	"output_type": "pyout",
	"prompt_number": 17,
	"text": [
	"11"
	]
	}
	],
	"prompt_number": 17
	},
	{
	"cell_type": "markdown",
	"metadata": {},
	"source": [
	"## \u0414\u0435\u0441\u043a\u0440\u0438\u043f\u0442\u043e\u0440\u044b"
	]
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"class ROValue(object):\n",
	" \n",
	" def __init__(self, att_name):\n",
	" self._att_name = att_name\n",
	" \n",
	" def __get__(self, inst, cls):\n",
	" assert inst, \"Thist is instance attr\"\n",
	" return getattr(inst, self._att_name)\n",
	" \n",
	" def __set__(self, inst, value):\n",
	" raise TypeError(\"Readonly!\")"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 18
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"class Our(object):\n",
	" _a = 42\n",
	" a = ROValue('_a')"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 19
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"Our().a"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"metadata": {},
	"output_type": "pyout",
	"prompt_number": 20,
	"text": [
	"42"
	]
	}
	],
	"prompt_number": 20
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"our = Our()\n",
	"our.a = 43"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"ename": "TypeError",
	"evalue": "Readonly!",
	"output_type": "pyerr",
	"traceback": [
	"\u001b[1;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[1;31mTypeError\u001b[0m Traceback (most recent call last)",
	"\u001b[1;32m<ipython-input-21-ba09226d8ba8>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m 1\u001b[0m \u001b[0mour\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mOur\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 2\u001b[1;33m \u001b[0mour\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0ma\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;36m43\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
	"\u001b[1;32m<ipython-input-18-bbdf8e7bb55f>\u001b[0m in \u001b[0;36m__set__\u001b[1;34m(self, inst, value)\u001b[0m\n\u001b[0;32m 9\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m 10\u001b[0m \u001b[1;32mdef\u001b[0m \u001b[0m__set__\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mself\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0minst\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mvalue\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m---> 11\u001b[1;33m \u001b[1;32mraise\u001b[0m \u001b[0mTypeError\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;34m\"Readonly!\"\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
	"\u001b[1;31mTypeError\u001b[0m: Readonly!"
	]
	}
	],
	"prompt_number": 21
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"class Cached(object):\n",
	" \n",
	" def __init__(self, att_name, generate):\n",
	" self._att_name = att_name\n",
	" self._generate = generate\n",
	" \n",
	" def __get__(self, inst, cls):\n",
	" assert inst, \"Thist is instance attr\"\n",
	" if hasattr(inst, self._att_name):\n",
	" return getattr(inst, self._att_name)\n",
	" val = self._generate(inst)\n",
	" setattr(inst, self._att_name, val)\n",
	" return val\n",
	" \n",
	" def __set__(self, inst, value):\n",
	" raise TypeError(\"Readonly!\")"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 22
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"def very_slow(obj):\n",
	" print \"Veryy slooow!\"\n",
	" return 1\n",
	"\n",
	"class Our(object):\n",
	" big_int = Cached('_big_int_cache', very_slow)"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 23
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"o = Our()"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 24
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"print o.big_int # \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0435 \u0432\u044b\u0447\u0438\u0441\u043b\u0438\u0442\u0441\u044f \u0442\u043e\u043b\u044c\u043a\u043e \u0442\u0443\u0442\n",
	"print o.big_int"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"output_type": "stream",
	"stream": "stdout",
	"text": [
	"Veryy slooow!\n",
	"1\n",
	"1\n"
	]
	}
	],
	"prompt_number": 25
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"class TypedAttr(object):\n",
	" def __init__(self, attr_name, value_name, typ):\n",
	" self._attr_name = attr_name\n",
	" self._value_name = value_name\n",
	" self._type = typ\n",
	"\n",
	" def __get__(self, inst, cls):\n",
	" assert inst\n",
	" return inst.__dict__[self._value_name]\n",
	" \n",
	" def __set__(self, inst, value):\n",
	" assert inst\n",
	" if not isinstance(value, self._type):\n",
	" raise TypeError(\n",
	" 'Value of attr \"%s\" must be %s' % (\n",
	" self._attr_name, self._type\n",
	" ))\n",
	" inst.__dict__[self._value_name] = value"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 26
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"class Point(object):\n",
	" x = TypedAttr('x', '_x', int)\n",
	" y = TypedAttr('y', '_y', int)\n"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 27
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"p = Point()\n",
	"p.x = 10\n",
	"p.y = \"asdasd\""
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"ename": "TypeError",
	"evalue": "Value of attr \"y\" must be <type 'int'>",
	"output_type": "pyerr",
	"traceback": [
	"\u001b[1;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[1;31mTypeError\u001b[0m Traceback (most recent call last)",
	"\u001b[1;32m<ipython-input-28-ca4e8f3ca389>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m 1\u001b[0m \u001b[0mp\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mPoint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m 2\u001b[0m \u001b[0mp\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mx\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;36m10\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 3\u001b[1;33m \u001b[0mp\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0my\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;34m\"asdasd\"\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
	"\u001b[1;32m<ipython-input-26-d9795cd9bdc5>\u001b[0m in \u001b[0;36m__set__\u001b[1;34m(self, inst, value)\u001b[0m\n\u001b[0;32m 14\u001b[0m raise TypeError(\n\u001b[0;32m 15\u001b[0m 'Value of attr \"%s\" must be %s' % (\n\u001b[1;32m---> 16\u001b[1;33m \u001b[0mself\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0m_attr_name\u001b[0m\u001b[1;33m,\u001b[0m \u001b[0mself\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0m_type\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m 17\u001b[0m ))\n\u001b[0;32m 18\u001b[0m \u001b[0minst\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0m__dict__\u001b[0m\u001b[1;33m[\u001b[0m\u001b[0mself\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0m_value_name\u001b[0m\u001b[1;33m]\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mvalue\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
	"\u001b[1;31mTypeError\u001b[0m: Value of attr \"y\" must be <type 'int'>"
	]
	}
	],
	"prompt_number": 28
	},
	{
	"cell_type": "markdown",
	"metadata": {},
	"source": [
	"## \u0414\u0435\u043a\u043e\u0440\u0430\u0446\u0438\u044f \u043a\u043b\u0430\u0441\u0441\u043e\u0432"
	]
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"def serializable(cls):\n",
	" cls.to_str = lambda self: str(self)\n",
	" return cls"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 29
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"@serializable\n",
	"class C(object):\n",
	" pass"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 30
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"C().to_str()"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"metadata": {},
	"output_type": "pyout",
	"prompt_number": 31,
	"text": [
	"'<__main__.C object at 0x93a68ac>'"
	]
	}
	],
	"prompt_number": 31
	},
	{
	"cell_type": "markdown",
	"metadata": {},
	"source": [
	"## \u041c\u0435\u0442\u0430\u043a\u043b\u0430\u0441\u0441\u044b"
	]
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"def with_defaults(name, bases, dic):\n",
	" orig = dic['__init__']\n",
	" dic['__init__'] = new.function(\n",
	" orig.func_code,\n",
	" orig.func_globals,\n",
	" orig.func_name,\n",
	" dic.get('_init_defaults', ())\n",
	" )\n",
	" return type(name, bases, dic)"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 32
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"class C(object):\n",
	" __metaclass__ = with_defaults\n",
	" \n",
	" _init_defaults = (5, 6)\n",
	" \n",
	" def __init__(self, a, b):\n",
	" print \"instantiated with args:\", a, b"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 33
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"c = C()"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"output_type": "stream",
	"stream": "stdout",
	"text": [
	"instantiated with args: 5 6\n"
	]
	}
	],
	"prompt_number": 34
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"class D(C):\n",
	" _init_defaults = (42, 24)"
	],
	"language": "python",
	"metadata": {},
	"outputs": [],
	"prompt_number": 35
	},
	{
	"cell_type": "code",
	"collapsed": false,
	"input": [
	"d = D()"
	],
	"language": "python",
	"metadata": {},
	"outputs": [
	{
	"output_type": "stream",
	"stream": "stdout",
	"text": [
	"instantiated with args: 5 6\n"
	]
	}
	],
	"prompt_number": 33
	},
	{
	"cell_type": "markdown",
	"metadata": {},
	"source": [
	"\u041f\u0435\u0440\u0435\u043a\u0440\u044b\u0442\u0438\u0435 ```_init_defaults``` \u043d\u0438\u0447\u0435\u0433\u043e \u043d\u0435 \u0434\u0430\u043b\u043e, \u0442.\u043a \u043c\u0435\u0442\u0430\u043a\u043b\u0430\u0441\u0441 \u0443\u0436\u0435 \u043e\u0442\u0440\u0430\u0431\u043e\u0442\u0430\u043b \u043e\u0434\u043d\u0430\u0436\u0434\u044b (\u0433\u0435\u043d\u0435\u0440\u0438\u0440\u0443\u044f ```\u0421```)"
	]
	},
	{
	"cell_type": "markdown",
	"metadata": {},
	"source": [
	"\u0441\u0441\u044b\u043b\u043a\u0438 \u043d\u0430 \u0442\u0435\u043c\u0443\n",
	"\n",
	"- [Python 3 Metaprogramming](https://www.youtube.com/watch?v=sPiWg5jSoZI)\n",
	"- [Python Metaprogramming for Mad Scientists and Evil Geniuses](https://www.youtube.com/watch?v=Adr_QuDZxuM)"
	]
	}
	],
	"metadata": {}
	}
	]
	}