如何在 php 中返回新实例

Question

I have the following code:

class Email_Driver
{
   public function testEmail_Driver()
    {
       echo "testEmail_Driver".RT;
    }
}
    
class Email_Smtp extends Email_Driver
{
    public function testEmail_Smtp()
    {
       echo "testEmail_Smtp".RT;
    }
}

class Email
{
  public $instance;

  public function __construct()
  {
      $this->instance = new Email_Smtp();
      return $this->instance;
  }
}


$mail = new Email();
var_dump($mail);
$mail->testEmail_Smtp();      //Fatal error: Uncaught Error: Call to undefined method Email::testEmail_Smtp()
$mail->testEmail_Driver();

How do I get access to methode testEmail_Smtp() and testEmail_Driver() in this case?

Answer 1

The code below should be enough. Basically the class Email now acts exactly the same as class Email_Smtp :

class Email_Driver
{
   public function testEmail_Driver()
    {
       echo "testEmail_Driver".PHP_EOL;
    }
}
    
class Email_Smtp extends Email_Driver
{
    public function testEmail_Smtp()
    {
       echo "testEmail_Smtp".PHP_EOL;
    }
}

class Email extends Email_Smtp 
{
  // any more methods
}

$mail = new Email();
var_dump($mail);
$mail->testEmail_Smtp();      
$mail->testEmail_Driver();

Answer 2

You are assigning subsiduary classes to $instance so in order to make you code work you need to use that instance

<?php
    define('RT','<br />');
    
    class Email_Driver{
        public function testEmail_Driver(){
            echo "testEmail_Driver".RT;
        }
    }
        
    class Email_Smtp extends Email_Driver{
        public function testEmail_Smtp(){
           echo "testEmail_Smtp".RT;
        }
    }

    class Email{
      public $instance;
      public function __construct(){
          $this->instance = new Email_Smtp();
      }
    }


    $mail = new Email();

    printf('<pre>%s</pre>',print_r($mail,true));
    $mail->instance->testEmail_Smtp();      //Fatal error: Uncaught Error: Call to undefined method Email::testEmail_Smtp()
    $mail->instance->testEmail_Driver();

?>

Which outputs:

Email Object
(
    [instance] => Email_Smtp Object
        (
        )

)
testEmail_Smtp
testEmail_Driver