추상 클래스를 사용하는 간단한 컬 래퍼 메소드?

Question

메신저 추상 클래스에서 좋은 연습을 시도하는 방법 그래서 간단한 컬 래퍼 클래스를 만들었지 만 불행히도 그것은 작동하지 않습니다.
추상적

<?php 
abstract class curl{ 
    private $url; 

    public function __construct($url){ 
     $this->url = $url ; 
    } 
    public function curl_grab_page() 
    { 
      $ch = curl_init(); 
      curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE); 
      curl_setopt($ch, CURLOPT_URL, $this->url); 
      curl_setopt($ch, CURLOPT_HEADER, TRUE); 
      curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']); 
      curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE); 
      curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE); 
      curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE); 
      ob_start(); // prevent any output 
      return curl_exec ($ch); // execute the curl command 
      ob_end_clean(); // stop preventing output 
      curl_close ($ch); 
    } 
    public abstract function getHTML(); 

} 
?> 

아이

<?php 
class google extends curl{ 
    private $url; 
    function __construct($url) { 
     parent::__construct($url); 
    } 
    function curl_grab_page(){ 
     parent::curl_grab_page(); 
    } 
    function getHTML(){ 
     return $this->curl_grab_page(); 
    } 
} 

는이 내가 내 첫 페이지에 전화하는 방법입니다.

<?php 
include 'classes/class.curl.php'; 
include 'classes/class.google.php'; 
$google = new google('http://www.google.com/'); 
echo $google->getHTML(); 
?> 

아무 것도 출력하지 않았습니다.

public function curl_grab_page() 
{ 
     $ch = curl_init(); 
     curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE); 
     curl_setopt($ch, CURLOPT_URL, $this->url); 
     curl_setopt($ch, CURLOPT_HEADER, TRUE); 
     curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']); 
     curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE); 
     curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE); 
     curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE); 

     // Don't need any output buffering b/c you set CURLOPT_RETURNTRANSFER to true, which means the results will be returned via curl_exec 
     //ob_start(); // prevent any output 
     //return curl_exec ($ch); // execute the curl command 
     //ob_end_clean(); // stop preventing output 

     $contents = curl_exec($ch); 

     curl_close ($ch); 

     return $contents; 
} 

을 그리고 자식 클래스 :
내가 별도로 기능을 시도하고 당신이 반환을 호출하기 전에 출력 버퍼의 결과를 지역화하지 않는 것처럼

Answer 1

이 보이는 잘 간다,이 시도

<?php 
class google extends curl{ 
    // Don't need this, if you set the parent's scope to protected which means child class has access 
    // private $url; 

    function __construct($url) { 
     parent::__construct($url); 
    } 

    // Don't really need this method unless you plan on doing some custom logic   
    function curl_grab_page(){ 

     // If you keep this method I added a return here so we can get the results of the call 
     return parent::curl_grab_page(); 
    } 

    function getHTML(){ 
     return $this->curl_grab_page(); 
    } 
}