即时添加方法到stdClass对象

Question

I want to add a function on an object that returns a specific value from that object.

I have the following code now:

    <?php
namespace sdk;
use core\Sdk;

class Contents extends Sdk {

    public $url;
    public $id;

    public function __call($method, $args) {
        if (isset($this->$method)) {
            $func = $this->$method;
            return call_user_func_array($func, $args);
        }
    }

    public function getContents($id = '') {
        $request = 'contents/list/'.$id;
        return $this->getRequest($request);
    }//getContents

    public function getContent($id) {
        $request = 'contents/detail/'.$id;
        $this->object = $this->getRequest($request);
        $this->object->getItemAttribute = function($attribute) {
            var_dump($this->object);
        };
        return $this->object;
    }//getContent

}//Class Contents

and I try to start the method via tis code

$contents->getContent(1);
$contents->object->getItemAttribute('titel');

But I keep getting the error "undefined method"

What am I doing wrong?

Answer 1

PHP is not Javascript. You cannot add methods to already existing instances of a class (or methods to an already-defined class, for that matter).

Here's some alternative ideas:

1. Use properties that are functions (that's in principle what you are doing now, just with a different invocation).

   $object->getItemAttribute = function($a) {
       return $object->{$a};
   }
   call_user_func($object->getItemAttribute);
   

   I actually would not recommend implementing this, as it will probably make your code difficult to comprehend and annoy the hell out of any future maintainer (including yourself).

2. Define a wrapper class that implements your new functions:

   class RequestWithAdditionalAttribute {
       private $wrapped;
       public function __construct(\stdClass $wrapped) {
           $this->wrapped = $wrapped;
       }
       public function getItemAttribute($a) {
           return $this->wrapped->{$a};
       }
   }
   
   $wrappedObject = new RequestWithAdditionalAttribute($object)
   

3. PHP 7 variant: Create an anonymous class:

   $wrappedObject = new class($object) {
       private $wrapped;
       public function __construct(\stdClass $wrapped) {
           $this->wrapped = $wrapped;
       }
       public function getItemAttribute($a) {
           return $this->wrapped->{$a};
       }
   };