Question

我想从父类中定义的函数中调用子类中定义的函数以获取某些逻辑。我收到未定义函数的错误。如何调用此函数。这是我的示例代码。

<?php
 class First
 {
     public function __construct()
     {
        echo "First class is initiated.";
     }
     public function call_child()
     {
       $this->get_ouput();
     }
  }
  class Second extends First
  {
     public function __construct()
     {
        parent::__construct();
     }
     public function get_output()
     {
        echo "Here is your output";
     }
  }
  $obj = new Second();
  $obj->call_child();

  ?>

Answer 1

调用get_output方法时出现错字。但是，您应该将First类和get_output方法定义为抽象方法，以便被其他类扩展/实现：

abstract class First
 {
     public function __construct()
     {
        echo "First class is initiated.";
     }

     abstract public function get_output();

     public function call_child()
     {
       $this->get_output();
     }
  }

  class Second extends First
  {
     public function get_output()
     {
        echo "Here is your output";
     }
  }

  $obj = new Second();
  $obj->call_child();

注意：如果Second类仅调用父构造函数，则可能无法定义该构造函数。

Answer 2

问题是您的函数调用名称中的拼写错误

<?php
 class First
 {
     public function __construct()
     {
        echo "First class is initiated.";
     }
     public function call_child()
     {
       $this->get_output(); //update the name here
     }
  }
  class Second extends First
  {
     public function __construct()
     {
        parent::__construct();
     }
     public function get_output()
     {
        echo "Here is your output";
     }
  }
  $obj = new Second();
  $obj->call_child();

  ?>

如何在父类的函数内调用子类的函数

2 个答案: