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   "cell_type": "markdown",
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   "source": [
    "## 9-2 MethodクラスとUnboundMethodクラス\n",
    "### 9-2-1 UnboundMethodオブジェクトを作る方法"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "#<UnboundMethod: Array#shift>"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "Array.instance_method(:shift)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "#<UnboundMethod: Array#shift>"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "[].method(:shift).unbind"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "true"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "Array.instance_method(:shift) === [].method(:shift).unbind"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "[[:req]]\n",
      "Array\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       ":<<"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "unbound_shift_operator = Array.instance_method(:<<)\n",
    "p unbound_shift_operator.arity\n",
    "p unbound_shift_operator.parameters\n",
    "p unbound_shift_operator.owner\n",
    "unbound_shift_operator.name"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "1"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "unbind_shift = [].method(:shift).unbind\n",
    "unbind_shift.bind([1, 2, 3])\n",
    "unbind_shift.bind([1, 2, 3]).call"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "SuperKlass\n",
      "Klass\n"
     ]
    },
    {
     "ename": "TypeError",
     "evalue": "bind argument must be an instance of SuperKlass",
     "output_type": "error",
     "traceback": [
      "\u001b[31mTypeError\u001b[0m: bind argument must be an instance of SuperKlass",
      "\u001b[37m<main>:24:in `bind'\u001b[0m",
      "\u001b[37m<main>:24:in `<main>'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/backend.rb:44:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/backend.rb:44:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/backend.rb:12:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/kernel.rb:87:in `execute_request'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/kernel.rb:47:in `dispatch'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/kernel.rb:37:in `run'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/command.rb:70:in `run_kernel'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/command.rb:34:in `run'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/bin/iruby:5:in `<top (required)>'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/bin/iruby:23:in `load'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/bin/iruby:23:in `<main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    "class SuperKlass\n",
    "  def super_method\n",
    "    self.class\n",
    "  end\n",
    "end\n",
    "\n",
    "class Klass < SuperKlass\n",
    "end\n",
    "\n",
    "class NotInheritKlass\n",
    "  def super_method\n",
    "    self.class\n",
    "  end\n",
    "end\n",
    "\n",
    "super_klass = SuperKlass.new\n",
    "klass = Klass.new\n",
    "not_inherit_klass = NotInheritKlass.new\n",
    "\n",
    "unbind_super_method = SuperKlass.instance_method(:super_method)\n",
    "p unbind_super_method.bind(super_klass).call\n",
    "\n",
    "p unbind_super_method.bind(klass).call\n",
    "\n",
    "unbind_super_method.bind(not_inherit_klass).call"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "次回、「9-3 MethodオブジェクトとProc」から"
   ]
  }
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