chapter32 finished

Author: xiongzwfire

chapter32/chapter32-异常基础.ipynb

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+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 第32章 异常基础"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "- 异常可以改变程序的控制流程，它可以根据错误自动地被触发，也能由代码触发和截获，异常语句主要有以下几种：\n",
+    "```python\n",
+    "try/except\n",
+    "    捕捉由Python或你引起的异常并恢复\n",
+    "try/finally\n",
+    "    无论异常是否发生，执行清理行为\n",
+    "raise\n",
+    "    手动在代码中触发异常\n",
+    "assert\n",
+    "    有条件地在代码中触发异常\n",
+    "with/as\n",
+    "    环境管理器\n",
+    "```"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 引发异常"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "- 异常能由Python或程序引发"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "got exception\n"
+     ]
+    }
+   ],
+   "source": [
+    "try:\n",
+    "    raise IndexError\n",
+    "except:\n",
+    "    print \"got exception\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "- assert也可以用来触发异常——它是一个有条件的raise，主要是在开发过程中用于调试"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {},
+   "outputs": [
+    {
+     "ename": "AssertionError",
+     "evalue": "Nobody expects the Spanish Inquisition!",
+     "output_type": "error",
+     "traceback": [
+      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+      "\u001b[0;31mAssertionError\u001b[0m                            Traceback (most recent call last)",
+      "\u001b[0;32m<ipython-input-2-1e7b91bac7dd>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0;32massert\u001b[0m \u001b[0mFalse\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m\"Nobody expects the Spanish Inquisition!\"\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
+      "\u001b[0;31mAssertionError\u001b[0m: Nobody expects the Spanish Inquisition!"
+     ]
+    }
+   ],
+   "source": [
+    "assert False, \"Nobody expects the Spanish Inquisition!\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 用户定义的异常"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "got Bad\n"
+     ]
+    }
+   ],
+   "source": [
+    "class Bad(Exception):\n",
+    "    pass\n",
+    "def doomed():\n",
+    "    raise Bad()\n",
+    "try:\n",
+    "    doomed()\n",
+    "except Bad:\n",
+    "    print \"got Bad\""
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}