PHP class extension and inheritance usage example code

PHP does not have multiple inheritance features. Even if it is a programming language that supports multiple inheritance, we rarely use this feature. In most people's opinion, multiple inheritance is not a good design method. If you want to add additional features to a class, you don't necessarily need to use inheritance. Here I provide a method to simulate multiple inheritance for reference. This article mainly introduces the extension and inheritance usage of php classes, and analyzes the php class inheritance and extension operation techniques in detail in the form of examples. Friends in need can refer to

<?php 
class Thread 
{ 
  var $topic; //帖子主题 
  var $body; //帖子内容 
  var $date; //帖子发布时间 
  var $author; //帖子作者 
  //函数Thread用于初始化变量等 
  function Thread() 
  { 
    //初始化变量 
  } 
  //函数Send用于提交新帖子 
  function Send() 
  { 
    //检测变量的合法性后执行插入操作将变量存储到数据库中 
  } 
  //函数Edit用于编辑帖子 
  function Edit() 
  { 
    //检测变量的合法性后执行更新操作将变量存储到数据库中 
  } 
  //函数Delete用于删除帖子 
  function Delete() 
  { 
    //检测作者的权限后将从数据库中将相关数据删除 
  } 
} 
class MainThread extends Thread 
{ 
  var $id; //帖子编号 
  var $board; //帖子所在讨论区 
  var $allowreply; //是否允许回复 
  //构造函数，用于初始化变量 
  function MainThread($id, $board, $allowreply) 
  { 
    //用于初始化变量 
  } 
  function Send() 
  { 
    //检测变量的合法性后执行插入操作将变量存储到数据库中 
    parent::Send(); //用于调用基类的Send函数 
  } 
  function Edit() 
  { 
    //检测变量的合法性后执行更新操作将变量存储到数据库中 
    parent::Edit(); //用于调用基类的Edit函数 
  } 
} 
$th = new Thread; //创建新对象 
if ($th instanceof Thread) //如果对象$th是Thread类型的，则输出Yes 
  echo "Yes"; 
else 
  echo "No"; 
?>

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