{
 "metadata": {
  "name": "module-class-object"
 },
 "nbformat": 3,
 "nbformat_minor": 0,
 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "# \u6a21\u5757(module), \u7c7b(class)\u548c\u5bf9\u8c61(object)\n",
      "\n",
      "\u672c\u8282\u5185\u5bb9\u53ef\u4ee5\u53c2\u8003\u8bfe\u672c[\u7ec3\u4e6040](http://learnpythonthehardway.org/book/ex40.html).\n",
      "\n",
      "## \u6a21\u5757\n",
      "\n",
      "\u6a21\u5757\u5c31\u662fPython\u811a\u672c\u6587\u4ef6. \u6bd4\u5982\u65b0\u5efa\u4e00\u4e2a\u6587\u4ef6`counter.py`:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "value = 0\n",
      "step = 1\n",
      "\n",
      "def increase():\n",
      "    global value\n",
      "    value += step"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 1
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "\u5728\u540c\u4e00\u7ea7\u76ee\u5f55\u7684\u5176\u5b83\u811a\u672c\u91cc, \u6216\u8005IPython notebook\u91cc, \u6211\u4eec\u53ef\u4ee5import\u8fd9\u4e2a\u6a21\u5757:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import counter\n",
      "print counter.value\n",
      "counter.increase()\n",
      "print counter.value"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "0\n",
        "1\n"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "\u6a21\u5757\u5c06\u6570\u636e\u548c\u51fd\u6570\u6253\u5305\u5728\u4e00\u8d77, \u4f7f\u5f97\u5916\u754c\u53ef\u4ee5\u65b9\u4fbf\u5730\u4f7f\u7528\u5176\"\u6210\u5458\"\u51fd\u6570\u6539\u53d8\u5176\u4e2d\u7684\u6570\u636e. \u4f46\u662f\u6a21\u5757\u53ea\u80fdimport\u4e00\u6b21, \u540e\u7eed\u7684import\u4e0d\u4f1a\u91cd\u65b0\u521d\u59cb\u5316\u8be5\u6a21\u5757(\u7528\u4e00\u4e9bhack\u7684\u65b9\u6cd5\u53ef\u4ee5\u91cd\u590dimport):"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import counter\n",
      "print counter.value"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1\n"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## \u7c7b\n",
      "\n",
      "\u4e00\u4e2a\u7c7b\u76f8\u5f53\u4e8e\u4e00\u4e2aPython\u811a\u672c, \u5373\u4e00\u4e2a\u6a21\u5757:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "class Counter(object):\n",
      "    \n",
      "    def __init__(self):\n",
      "        self.value = 0\n",
      "        self.step = 1\n",
      "        \n",
      "    def increase(self):\n",
      "        self.value += self.step"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 4
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "\u5176\u4e2d\u6570\u636e\u5728\u7279\u6b8a\u51fd\u6570`__init__`\u4e2d\u5b9a\u4e49, \u800c\u51fd\u6570\u5219\u5728`class`\u7684\u4e0b\u4e00\u7ea7\u5b9a\u4e49."
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## \u5bf9\u8c61\n",
      "\n",
      "\u6a21\u5757\u9700\u8981import\u624d\u80fd\u4f7f\u7528, \u7c7b\u5219\u9700\u8981\u5b9e\u4f8b\u5316(instantiate). \u6240\u8c13\u5b9e\u4f8b\u5316\u5c31\u662f\u521b\u5efa(create)\u7684\u610f\u601d. \u5b9e\u9645\u4e0a\u5c31\u662f\u8c03\u7528\u4e86`__init__`\u51fd\u6570, \u5206\u914d\u4e00\u5757\u5185\u5b58\u5e76\u547d\u540d\u4e3a`self`, \u518d\u521d\u59cb\u5316\u5176\u4e2d\u7684\u6570\u636e."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "counter = Counter()\n",
      "print counter.value\n",
      "counter.increase()\n",
      "print counter.value"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "0\n",
        "1\n"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "\u4e0e\u6a21\u5757\u4e0d\u540c, \u7c7b\u53ef\u4ee5\u591a\u6b21\u5b9e\u4f8b\u5316, \u800c\u6a21\u5757\u53ea\u80fdimport\u4e00\u6b21:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "c1 = Counter()\n",
      "print c1.value\n",
      "c1.increase()\n",
      "print c1.value\n",
      "c2 = Counter()\n",
      "print c2.value"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "0\n",
        "1\n",
        "0\n"
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "\u7c7b\u4e0e\u6a21\u5757\u7684\u53e6\u4e00\u4e2a\u4e0d\u540c\u4e4b\u5904\u5728\u4e8e\u7c7b\u53ef\u4ee5\u6307\u5b9a\u5176\u521d\u59cb\u5316\u65b9\u5f0f:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "class Counter(object):\n",
      "    \n",
      "    def __init__(self, step=1):\n",
      "        self.value = 0\n",
      "        self.step = step\n",
      "        \n",
      "    def increase(self):\n",
      "        self.value += self.step\n",
      "        \n",
      "counter = Counter(2)\n",
      "print counter.value\n",
      "counter.increase()\n",
      "print counter.value"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "0\n",
        "2\n"
       ]
      }
     ],
     "prompt_number": 7
    }
   ],
   "metadata": {}
  }
 ]
}