20190102

Author: delphiduan

.ipynb_checkpoints/Python_Learning_09-checkpoint.ipynb

@@ -220,7 +220,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 2,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -229,6 +229,234 @@
     "class B(A):\n",
     "    pass"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "- 单继承与多继承的优缺点：\n",
+    "    - 单继承\n",
+    "        - 优点：传承有序逻辑清晰语法简单隐患少\n",
+    "        - 缺点：功能不能无限扩展，只能在当前唯一的继承链中扩展\n",
+    "    - 多继承\n",
+    "        - 优点：类的扩展方便\n",
+    "        - 缺点：类关系混乱\n",
+    "    - 菱形继承/钻石继承的问题\n",
+    "        - MRO解决多继承的问题\n",
+    "            - MRO多个继承中，用于保存继承顺序的一个列表\n",
+    "            - python本身采用C3 算法来解决多继承的问题\n",
+    "            - MRO列表的计算原则：\n",
+    "                - 子类永远继承父类\n",
+    "                - 如果出现多个继承，则根据继承语法中括号的书写顺序\n",
+    "                - 如果多个继承继承了同一个父类，孙子类只会选择语法括号中的第一个父类的父类"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "- 构成函数\n",
+    "    - 在对象进行实例化的时候，系统自动调用的一个函数叫做构造函数，通常此函数用来对实例对象进行初始化。\n",
+    "    - 构造函数一定\n"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "in inint func\n",
+      "B\n"
+     ]
+    }
+   ],
+   "source": [
+    "class Person():\n",
+    "    #对Person进行实例化的时候\n",
+    "    #姓名要\n",
+    "    #年龄\n",
+    "    #构造函数初始化\n",
+    "    def __init__(self):\n",
+    "        self.name = \"yumi\"\n",
+    "        self.age = 18\n",
+    "        print(\"in inint func\")\n",
+    "#实例化一个人\n",
+    "p = Person()\n",
+    "\n",
+    "class A():\n",
+    "    def __init__(self):\n",
+    "        print(\"A\")\n",
+    "class B(A):\n",
+    "    def __init__(self,name):\n",
+    "        print(\"B\")\n",
+    "class C(B):\n",
+    "#     def __init__(self):\n",
+    "#         print(\"C\")\n",
+    "    pass\n",
+    "D = C(\"yumi\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 28,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "B\n",
+      "new\n",
+      "****************************************************************************************************\n",
+      "B\n",
+      "new\n"
+     ]
+    }
+   ],
+   "source": [
+    "class A():\n",
+    "    def __init__(self):\n",
+    "        print(\"A\")\n",
+    "class B(A):\n",
+    "    def __init__(self,name):\n",
+    "        print(\"B\")\n",
+    "class C(B):\n",
+    "    def __init__(self,name):\n",
+    "        #调用父类函数\n",
+    "        B.__init__(self,name)\n",
+    "        #增加自己的功能\n",
+    "        print(\"new\")\n",
+    "D = C(\"yumi\")\n",
+    "\n",
+    "print(\"*\"*100)\n",
+    "\n",
+    "class C(B):\n",
+    "    def __init__(self,name):\n",
+    "        #调用父类函数\n",
+    "        super(C,self).__init__(name)\n",
+    "        print(\"new\")\n",
+    "D = C(\"yumi\")    "
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 6.3 多态\n",
+    "    - 多态就是一个对象在不同情况下有不同的状态出现\n",
+    "    - 多态不是语法，是一种设计思想\n",
+    "    - 多态性，一种调用方法，不同的执行效果\n",
+    "    - 多态：同一事物的多种形态，动物分人类，鸟类，鱼类\n",
+    "    \n",
+    "- Mixin设计模式\n",
+    "    - 多继承语法来现实Mixin\n",
+    "    - 必须单一功能\n",
+    "    - 职责必须单一\n",
+    "    - Mixin不依赖子类实现\n",
+    "    - 子类没继承Mixin类，照样能工作\n",
+    "   \n",
+    "- 优点\n",
+    "    - 使用Mixin可以在不对类进行任何修改的情况下，扩充功能\n",
+    "    - 可以方便维护不同的功能组件的划分\n",
+    "    - 可以根据需要调整类的组合\n",
+    "    - 可以避免创建很多新的类，导致类的继承混乱\n",
+    "    "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 48,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "(<class '__main__.Tutor'>, <class '__main__.Teacher'>, <class '__main__.Student'>, <class '__main__.Person'>, <class 'object'>)\n",
+      "{}\n",
+      "{'__module__': '__main__', '__doc__': None}\n",
+      "****************************************************************************************************\n",
+      "(<class '__main__.NewTutor'>, <class '__main__.Person'>, <class '__main__.TeacherMixin'>, <class '__main__.StudentMixin'>, <class 'object'>)\n",
+      "{}\n",
+      "{'__module__': '__main__', '__doc__': None}\n"
+     ]
+    }
+   ],
+   "source": [
+    "#Mixin案例\n",
+    "class Person():\n",
+    "    def eat(self):\n",
+    "        print(\"eat\")\n",
+    "    def drink(self):\n",
+    "        print(\"drink\")\n",
+    "    def swim(self):\n",
+    "        print(\"swim\")\n",
+    "class Teacher(Person):\n",
+    "    def work(self):\n",
+    "        print(\"work\")\n",
+    "class Student(Person):\n",
+    "    def study(self):\n",
+    "        print(\"study\")\n",
+    "class Tutor(Teacher,Student):\n",
+    "    pass\n",
+    "yumi = Tutor()\n",
+    "print(Tutor.__mro__)\n",
+    "print(yumi.__dict__)\n",
+    "print(Tutor.__dict__)\n",
+    "print(\"*\"*100)\n",
+    "class TeacherMixin():\n",
+    "    def work(self):\n",
+    "        print(\"work\")\n",
+    "class StudentMixin():\n",
+    "    def study(self):\n",
+    "         print(\"study\")\n",
+    "class NewTutor(Person,TeacherMixin,StudentMixin):\n",
+    "    pass\n",
+    "delphi = NewTutor()\n",
+    "print(NewTutor.__mro__)\n",
+    "print(delphi.__dict__)\n",
+    "print(NewTutor.__dict__)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 6.4类的相关函数\n",
+    "- issubclass检测一个类是另一个类的子类\n",
+    "- isintance检测对象是否是一个类的实例\n",
+    "- hasattr：检测成员\n",
+    "- dir：获取对象列表"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 49,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Help on built-in function getattr in module builtins:\n",
+      "\n",
+      "getattr(...)\n",
+      "    getattr(object, name[, default]) -> value\n",
+      "    \n",
+      "    Get a named attribute from an object; getattr(x, 'y') is equivalent to x.y.\n",
+      "    When a default argument is given, it is returned when the attribute doesn't\n",
+      "    exist; without it, an exception is raised in that case.\n",
+      "\n"
+     ]
+    }
+   ],
+   "source": [
+    "help(getattr)"
+   ]
   }
  ],
  "metadata": {

.ipynb_checkpoints/Python_Learning_10-checkpoint.ipynb

@@ -0,0 +1,6 @@
+{
+ "cells": [],
+ "metadata": {},
+ "nbformat": 4,
+ "nbformat_minor": 2
+}