{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 10-4 イベントをフックする\n",
    "### 10-4-1 モジュールがincludeやextendされたときのフック"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0\n",
      "3\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[IncludeClass1, IncludeClass2, IncludeClass3]"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "module IncludedCount\n",
    "  class << self\n",
    "    def included(klass)\n",
    "      @included ||= []\n",
    "      @included << klass\n",
    "    end\n",
    "    \n",
    "    def included_module_and_class\n",
    "      @included\n",
    "    end\n",
    "    \n",
    "    def included_count\n",
    "      @included&.count || 0\n",
    "    end\n",
    "  end\n",
    "end\n",
    "\n",
    "p IncludedCount.included_count\n",
    "\n",
    "class IncludeClass1\n",
    "  include IncludedCount\n",
    "end\n",
    "\n",
    "class IncludeClass2\n",
    "  include IncludedCount\n",
    "end\n",
    "\n",
    "class IncludeClass3\n",
    "  include IncludedCount\n",
    "end\n",
    "\n",
    "p IncludedCount.included_count\n",
    "\n",
    "IncludedCount.included_module_and_class"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 10-4-2 継承されたときのフック"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "クラス定義式の前\n",
      "[InheritedTimingSubClass, InheritedTiming, Object, JSON::Ext::Generator::GeneratorMethods::Object, Kernel, BasicObject]\n",
      "true\n",
      "false\n",
      "クラス定義式の後\n",
      "true\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "true"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "class InheritedTiming\n",
    "  class << self\n",
    "    private\n",
    "    \n",
    "    def inherited(subclass)\n",
    "      p subclass.ancestors\n",
    "      p subclass.instance_methods.include? :super_method\n",
    "      p subclass.instance_methods.include? :subclass_method\n",
    "    end\n",
    "  end\n",
    "  \n",
    "  def super_method\n",
    "  end\n",
    "end\n",
    "\n",
    "puts \"クラス定義式の前\"\n",
    "\n",
    "class InheritedTimingSubClass < InheritedTiming\n",
    "  puts \"クラス定義式の後\"\n",
    "  \n",
    "  def subclass_method\n",
    "  end\n",
    "end\n",
    "\n",
    "p InheritedTimingSubClass.instance_methods.include? :super_method\n",
    "InheritedTimingSubClass.instance_methods.include? :subclass_method"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 10-4-3 メソッドに対して操作が行われたときのフック\n",
    "■メソッドが追加されたら処理をしたい"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "method added: after_added_method\n",
      "method added: add_from_define_method\n",
      "method added: add_from_class_eval\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       ":add_from_class_eval"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "class AddedMethodClass\n",
    "  def before_added_method; end\n",
    "  \n",
    "  class << self\n",
    "    private\n",
    "    def method_added(method_name)\n",
    "      puts \"method added: #{method_name}\"\n",
    "    end\n",
    "  end\n",
    "  \n",
    "  def after_added_method; end\n",
    "  define_method :add_from_define_method, ->(){}\n",
    "end\n",
    "\n",
    "AddedMethodClass.class_eval do\n",
    "  def add_from_class_eval; end\n",
    "end"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "rescued\n",
      "succeeded\n"
     ]
    }
   ],
   "source": [
    "class BrokenMethodClass\n",
    "  class << self\n",
    "    private\n",
    "    def method_added(method_name)\n",
    "      raise \"Wow!\"\n",
    "    end\n",
    "  end\n",
    "  \n",
    "  def after_added_method\n",
    "    puts \"succeeded\"\n",
    "  end\n",
    "rescue\n",
    "  puts \"rescued\"\n",
    "end\n",
    "\n",
    "BrokenMethodClass.new.after_added_method"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "`method_added` はメソッド定義の後に実行される"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "第一部完！\n",
    "次回以降は Part4 から読みたい節をピックアップして読む"
   ]
  }
 ],
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