{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 6-2-4 メソッドの定義\n",
    "\n",
    "リスト 6.13 継承とincludeした時のメソッド優先順序"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":second_include_module"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "module FirstIncludeModule\n",
    "  def same_name_method\n",
    "    :first_include_module\n",
    "  end\n",
    "end\n",
    "\n",
    "module SecondIncludeModule\n",
    "  def same_name_method\n",
    "    :second_include_module\n",
    "  end\n",
    "end\n",
    "\n",
    "class Klass\n",
    "  include FirstIncludeModule\n",
    "  include SecondIncludeModule\n",
    "end\n",
    "\n",
    "object = Klass.new\n",
    "object.same_name_method"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":first_include_module"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "class Klass\n",
    "  define_method :same_name_method, FirstIncludeModule.instance_method(:same_name_method)\n",
    "end\n",
    "\n",
    "object = Klass.new\n",
    "object.same_name_method"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 6-2-5 MethodTransplanting"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":un_include_module_method"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "module UnIncludeModule\n",
    "  def un_include_module_method\n",
    "    :un_include_module_method\n",
    "  end\n",
    "end\n",
    "\n",
    "class Klass2\n",
    "  # TypeErrr にならない\n",
    "  define_method :un_include_module_method, UnIncludeModule.instance_method(:un_include_module_method)\n",
    "end\n",
    "\n",
    "object = Klass2.new\n",
    "object.un_include_module_method"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 6-3 特異クラス\n",
    "### 6-3-1 特異クラスと特異メソッド"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":new_singleton_method"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "class OriginalClass\n",
    "end\n",
    "\n",
    "obj = OriginalClass.new\n",
    "\n",
    "def obj.new_singleton_method\n",
    "  :new_singleton_method\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "false"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "obj.class.method_defined? :new_singleton_method"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "true"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "obj.singleton_class.method_defined? :new_singleton_method"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 6-3-2 特異クラスの確認方法"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "#<Klass3:0x00007fd7bfb0a1f0>\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "#<Class:#<Klass3:0x00007fd7bfb0a1f0>>"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "class Klass3; end\n",
    "\n",
    "p klass = Klass3.new\n",
    "klass.singleton_class"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "true"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "KLASS_OBJECT = klass\n",
    "\n",
    "class << klass; self; end == KLASS_OBJECT.singleton_class"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 6-3-3 特異クラスが作成されるタイミング"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":define_singleton_method"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "obj = Object.new\n",
    "\n",
    "def obj.define_singleton_method\n",
    "  :singleton_method\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [],
   "source": [
    "class << obj\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "#<Class:#<Object:0x00007fd7bf9819a0>>"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "obj.singleton_class"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 6-3-4 オブジェクトと特異クラス"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "OriginalClass2"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "class OriginalClass2\n",
    "end\n",
    "\n",
    "obj = OriginalClass2.new\n",
    "obj.singleton_class.superclass"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "false\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "true"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "p obj.instance_of? obj.singleton_class\n",
    "obj.instance_of? OriginalClass2"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 6-3-5 特異クラスを持てないオブジェクト"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "can't define singleton",
     "output_type": "error",
     "traceback": [
      "\u001b[31mTypeError\u001b[0m: can't define singleton",
      "\u001b[37m(pry):82:in `singleton_class'\u001b[0m",
      "\u001b[37m(pry):82:in `<main>'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `evaluate_ruby'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:355:in `handle_line'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:274:in `block (2 levels) in eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `catch'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `block in eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `catch'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:66:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:12:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:87:in `execute_request'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:47:in `dispatch'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:37:in `run'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:70:in `run_kernel'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:34:in `run'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/bin/iruby:5:in `<top (required)>'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/bin/iruby:23:in `load'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/bin/iruby:23:in `<main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    "1.singleton_class"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "can't define singleton",
     "output_type": "error",
     "traceback": [
      "\u001b[31mTypeError\u001b[0m: can't define singleton",
      "\u001b[37m(pry):83:in `singleton_class'\u001b[0m",
      "\u001b[37m(pry):83:in `<main>'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `evaluate_ruby'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:355:in `handle_line'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:274:in `block (2 levels) in eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `catch'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `block in eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `catch'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:66:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:12:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:87:in `execute_request'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:47:in `dispatch'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:37:in `run'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:70:in `run_kernel'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:34:in `run'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/bin/iruby:5:in `<top (required)>'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/bin/iruby:23:in `load'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/bin/iruby:23:in `<main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    ":symbol.singleton_class"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "TrueClass\n",
      "FalseClass\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "NilClass"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "p true.singleton_class\n",
    "p false.singleton_class\n",
    "nil.singleton_class"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 6-3-6 特異クラスの特徴"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "#<Klass:0x00007fd7c0a53fa8>\n",
      "#<Class:#<Klass:0x00007fd7c0a53fa8>>\n"
     ]
    },
    {
     "ename": "TypeError",
     "evalue": "can't create instance of singleton class",
     "output_type": "error",
     "traceback": [
      "\u001b[31mTypeError\u001b[0m: can't create instance of singleton class",
      "\u001b[37m(pry):93:in `new'\u001b[0m",
      "\u001b[37m(pry):93:in `<main>'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `evaluate_ruby'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:355:in `handle_line'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:274:in `block (2 levels) in eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `catch'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `block in eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `catch'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:66:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:12:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:87:in `execute_request'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:47:in `dispatch'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:37:in `run'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:70:in `run_kernel'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:34:in `run'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/bin/iruby:5:in `<top (required)>'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/bin/iruby:23:in `load'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/bin/iruby:23:in `<main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    "class Klass3; end\n",
    "\n",
    "p klass = Klass.new\n",
    "\n",
    "p EigenClass = klass.singleton_class\n",
    "\n",
    "EigenClass.new"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "can't make subclass of singleton class",
     "output_type": "error",
     "traceback": [
      "\u001b[31mTypeError\u001b[0m: can't make subclass of singleton class",
      "\u001b[37m(pry):94:in `<main>'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `evaluate_ruby'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:355:in `handle_line'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:274:in `block (2 levels) in eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `catch'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `block in eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `catch'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:66:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:12:in `eval'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:87:in `execute_request'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:47:in `dispatch'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:37:in `run'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:70:in `run_kernel'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:34:in `run'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/lib/ruby/gems/2.6.0/gems/iruby-0.3/bin/iruby:5:in `<top (required)>'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/bin/iruby:23:in `load'\u001b[0m",
      "\u001b[37m/Users/ketchup/.rbenv/versions/2.6.0/bin/iruby:23:in `<main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    "class NewClass < EigenClass\n",
    "end"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 6-3-7 特異クラスとObject#extend"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":extend_method"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "module ExtendedModule\n",
    "  def extend_method\n",
    "    :extend_method\n",
    "  end\n",
    "end\n",
    "\n",
    "obj = Object.new\n",
    "obj.extend ExtendedModule\n",
    "\n",
    "obj.extend_method"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[#<Class:#<Object:0x00007fd7bfbd98d8>>, Object, PP::ObjectMixin, JSON::Ext::Generator::GeneratorMethods::Object, Kernel, BasicObject]\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[#<Class:#<Object:0x00007fd7bfbd98d8>>, ExtendedModule, Object, PP::ObjectMixin, JSON::Ext::Generator::GeneratorMethods::Object, Kernel, BasicObject]"
      ]
     },
     "execution_count": 23,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "obj = Object.new\n",
    "p obj.singleton_class.ancestors\n",
    "\n",
    "obj.extend ExtendedModule\n",
    "obj.singleton_class.ancestors"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 6-3-8 特異クラスを使う"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "#<Object:0x00007fd7bfc025d0>"
      ]
     },
     "execution_count": 24,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "SINGLETON_OBJECT = Object.new"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":only_method"
      ]
     },
     "execution_count": 25,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "class << SINGLETON_OBJECT\n",
    "  def only_method\n",
    "    :only_method\n",
    "  end\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "#<Class:#<Object:0x00007fd7bfc025d0>>"
      ]
     },
     "execution_count": 26,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "SingletonClass = SINGLETON_OBJECT.singleton_class"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":instance_get"
      ]
     },
     "execution_count": 27,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "def SingletonClass.instance_get\n",
    "  SINGLETON_OBJECT\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":only_method"
      ]
     },
     "execution_count": 28,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "SingletonClass.instance_get.only_method"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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