{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 7-3 method_missing"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "ename": "NoMethodError",
     "evalue": "undefined method `no_method' for main:Object",
     "output_type": "error",
     "traceback": [
      "\u001b[31mNoMethodError\u001b[0m: undefined method `no_method' for main:Object",
      "\u001b[37m(pry):1:in `<main>'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `evaluate_ruby'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:355:in `handle_line'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:274:in `block (2 levels) in eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `catch'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `block in eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `catch'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:66:in `eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:12:in `eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:87:in `execute_request'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:47:in `dispatch'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:37:in `run'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:70:in `run_kernel'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:34:in `run'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/bin/iruby:5:in `<top (required)>'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/bin/iruby:23:in `load'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/bin/iruby:23:in `<main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    "no_method()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "# BasicObject#method_missingのコードはうまく動かなかったのでスキップ"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Kernel.#caller の `.#` はモジュール関数?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    " # 7-3-2 method_missingの使い方"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":initialize"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "class DelegateArray\n",
    "  def initialize\n",
    "    @array = []\n",
    "  end\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "ename": "NoMethodError",
     "evalue": "undefined method `<<' for #<DelegateArray:0x000055c214dff648 @array=[]>",
     "output_type": "error",
     "traceback": [
      "\u001b[31mNoMethodError\u001b[0m: undefined method `<<' for #<DelegateArray:0x000055c214dff648 @array=[]>",
      "\u001b[37m(pry):14:in `<main>'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `evaluate_ruby'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:355:in `handle_line'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:274:in `block (2 levels) in eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `catch'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `block in eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `catch'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:66:in `eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:12:in `eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:87:in `execute_request'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:47:in `dispatch'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:37:in `run'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:70:in `run_kernel'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:34:in `run'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/bin/iruby:5:in `<top (required)>'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/bin/iruby:23:in `load'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/bin/iruby:23:in `<main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    "delegate_array = DelegateArray.new\n",
    "delegate_array << 1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":method_missing"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "class DelegateArray\n",
    "  def method_missing(name, *args)\n",
    "    @array.__send__ name, *args\n",
    "  end\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[1]"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "delegate_array << 1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[1, 2]"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "delegate_array << 2"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 7-3-3 注意点"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":method_missing"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "class LoopMethodMissingClass\n",
    "  def method_missing(name, *args)\n",
    "    __send__(name)\n",
    "  end\n",
    "end\n",
    "\n",
    "# LoopMethodMissingClass.new.no_method # 無限ループ!"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":method_missing"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "class OverrideMethodMissing\n",
    "  def method_missing(method_name, *args)\n",
    "    if method_name == :target_method\n",
    "      return 'target_method is called'\n",
    "    end\n",
    "    \n",
    "    super\n",
    "  end\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "ename": "NoMethodError",
     "evalue": "undefined method `no_method' for #<OverrideMethodMissing:0x000055c2147f9cd0>",
     "output_type": "error",
     "traceback": [
      "\u001b[31mNoMethodError\u001b[0m: undefined method `no_method' for #<OverrideMethodMissing:0x000055c2147f9cd0>",
      "\u001b[37m(pry):36:in `method_missing'\u001b[0m",
      "\u001b[37m(pry):39:in `<main>'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:387:in `evaluate_ruby'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:355:in `handle_line'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:274:in `block (2 levels) in eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `catch'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:273:in `block in eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `catch'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/pry-0.12.2/lib/pry/pry_instance.rb:272:in `eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:66:in `eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/backend.rb:12:in `eval'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:87:in `execute_request'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:47:in `dispatch'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/kernel.rb:37:in `run'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:70:in `run_kernel'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/lib/iruby/command.rb:34:in `run'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/gems/iruby-0.3/bin/iruby:5:in `<top (required)>'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/bin/iruby:23:in `load'\u001b[0m",
      "\u001b[37m/home/jovyan/.gem/ruby/2.6.0/bin/iruby:23:in `<main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    "OverrideMethodMissing.new.no_method"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "\"target_method is called\""
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "OverrideMethodMissing.new.target_method"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# railsでmethod_missingが使われているところ\n",
    "# https://github.com/rails/rails/blob/607d77ab073581172a66b26e2807790cd723719e/activerecord/lib/active_record/relation/delegation.rb#L103-L110"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       ":method_missing"
      ]
     },
     "execution_count": 24,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# ActiveSupport#StringInquirer の method_missing\n",
    "class StringInquirer < String\n",
    "  def method_missing(method_name, *arguments)\n",
    "    if method_name[-1] == \"?\"\n",
    "      self == method_name[0..-2]\n",
    "    else\n",
    "      super\n",
    "    end\n",
    "  end\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "true\n",
      "false\n"
     ]
    }
   ],
   "source": [
    "string = StringInquirer.new(\"foo\")\n",
    "puts string.foo?\n",
    "puts string.bar?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 次回は7-4 evalから"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Ruby 2.6.2",
   "language": "ruby",
   "name": "ruby"
  },
  "language_info": {
   "file_extension": ".rb",
   "mimetype": "application/x-ruby",
   "name": "ruby",
   "version": "2.6.2"
  }
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