ch04-Python面向对象编程/04-04公有、私有、特殊以及静态方法和属性.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "6c276828",
   "metadata": {},
   "source": [
    "# 公有、私有、特殊以及静态的方法和属性\n",
    "\n",
    "一些以 `_` 开头的都是对象的特殊方法和属性。通常来说：\n",
    "\n",
    "- 以字母开头都是公有的方法和属性，可以直接调用；\n",
    "- 在Python中，“私有”的方法和属性以`_`开头，不过，并不存在真正私有的方法和属性，所谓“私有”只是不会被代码自动完成所记录，无法在按<TAB>键时自动补全。\n",
    "- 以`__`开头并以`__`结尾的是一些系统内置的属性和方法。\n",
    "- 以`__`开头不以`__`结尾的是一些更加特殊的方法，调用方式最为复杂。\n",
    "- 装饰器@staticmethod可以生成一个静态方法，静态方法可以用类本身去调用，在定义时，静态方法不需要加self参数。\n",
    "\n",
    "例如："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "2d3c089b",
   "metadata": {},
   "outputs": [],
   "source": [
    "class MyClass(object):\n",
    "    @staticmethod\n",
    "    def static():\n",
    "        print(\"I'm a static method!\")\n",
    "\n",
    "    pub = \"public\"\n",
    "\n",
    "    def __init__(self):\n",
    "        self._spe = \"special\"\n",
    "        print(\"I'm a special method!\")\n",
    "\n",
    "    def _private(self):\n",
    "        print(\"I'm a private method!\")\n",
    "\n",
    "    def public(self):\n",
    "        print(\"I'm a public method!\")\n",
    "\n",
    "    def __really_special(self):\n",
    "        print(\"I'm a really special method!\")\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "d171116d",
   "metadata": {},
   "source": [
    "构造对象时调用了一个特殊的方法`.__init__()`："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "4b33c44b",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "I'm a special method!\n"
     ]
    }
   ],
   "source": [
    "m = MyClass()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "35a1d0fe",
   "metadata": {},
   "source": [
    "查看公有属性和特殊属性："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "27337836",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'public'"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "m.pub"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "68a9de7b",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'special'"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "m._spe"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "99e5e999",
   "metadata": {},
   "source": [
    "公有方法："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "a4014969",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "I'm a public method!\n"
     ]
    }
   ],
   "source": [
    "m.public()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "01b0d226",
   "metadata": {},
   "source": [
    "私有方法："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "895a7f7c",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "I'm a private method!\n"
     ]
    }
   ],
   "source": [
    "m._private()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "cc74e7da",
   "metadata": {},
   "source": [
    "以`__`开头不以`__`结尾的方法调用方式有所不同，需要加上类名："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "6a0f9e3f",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "I'm a really special method!\n"
     ]
    }
   ],
   "source": [
    "m._MyClass__really_special()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "be41bdc1",
   "metadata": {},
   "source": [
    "静态方法用类去调用："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "6cf4be62",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "I'm a static method!\n"
     ]
    }
   ],
   "source": [
    "MyClass.static()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "fdc05823",
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3 (ipykernel)",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.9.10"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 5
}