PHP Magic Methods - enforce defining of class properties

Juraj — Fri, 10 Apr 2009 16:53:23 +0000

Sometimes it’s desirable to have a control over which properties can be assigned to an object. Typo mistakes, duplicating of property names, among others, are the commons pitfalls of PHP’s ability to set/get properties without defining them in a class.

The MagicMethods class enforces that class properties are defined in a class before we can set or get their values. Any class that extends this class will benefit from this behavior (unless magic method get overridden in the exteding class). If a getter or setter method is needed to manipulate a property, MagicMethod class will use these instead of directly accessing the value.

This functionality is especially handy for value objects or config classes.

Example:

class ConfigMagic extends MagicMethods_Abstract
{
  // note $name is protected, not private, so that MagicMethods_Abstract can access it
  protected $name;
 
  public function getName()
  {
     // provides more complex way of getting a variable
     return $this-&gt;name;
  }
 
  public function setName($value)
  {
    // provides more complex way of setting a variable
   $this-&gt;name = $value;
  }
}
 
$config = new ConfigMagic();
$config-&gt;name = 'magic';
var_dump($config-&gt;name); // string 'magic' (length=5)
var_dump(isset($config-&gt;name));  // true
unset($config-&gt;name);
var_dump(isset($config-&gt;name)); // false
 
// Exception: Cannot set property 'nonExisting'. Not defined in class ConfigMagic ...
$config-&gt;nonExisting = 'magic';

Download the files:
MagicMethods_Abstract.php
MagicMethodsException.php

 /**
 * Magic Methods
 * Provides magic methods for other classes, enforces property names.
 * Undefined property name throws an exception
 *
 * @package DAO
 * @uses MagicMethodsException
 * @example MyOwnClass extends MagicMethods_Abstract
 * @license Free to use and modify (including commercial use)
 * @see http://php.net/manual/en/language.oop5.magic.php
 * @author Juraj Seffer 
 * @copyright 2009, Juraj Seffer
 * @version $Id$
 * @access public
 */
abstract class MagicMethods_Abstract
{
  /**
   * Magic getter
   *
   * @param string $property
   * @access protected
   * @return mixed
   */
  protected function __get($property)
  {
    $getterMethod = "get" . strtoupper($property);
    if (method_exists($this, $getterMethod)) {
      return $this-&gt;$getterMethod();
    }
    else if (!property_exists($this, $property)) {
      throw new MagicMethodsException(
        "Cannot get property '$property'. Not defined in class " . get_class($this)
      );
    }
    else {
      return $this-&gt;$property;
    }
  }
 
  /**
   * Magic setter
   *
   * @param string $property
   * @param mixed $value
   * @access protected
   * @return void
   */
  protected function __set($property, $value)
  {
    $setterMethod = "set" . strtoupper($property);
    if (method_exists($this, $setterMethod)) {
      return $this-&gt;$setterMethod($value);
    }
    else if (!property_exists($this, $property)) {
      throw new MagicMethodsException(
        "Cannot set property '$property'. Not defined in class " . get_class($this)
      );
    }
    else {
      $this-&gt;$property = $value;
    }
  }
 
  /**
   * Magic isset
   *
   * @param string $property
   * @access protected
   * @return mixed
   */
  protected function __isset($property)
  {
    if (!property_exists($this, $property)) {
      throw new MagicMethodsException(
        "Property '$property' not defined in class " . get_class($this)
      );
    }
    else {
      return isset($this-&gt;$property);
    }
  }
 
  /**
   * Magic unset
   *
   * @param string $property
   * @access protected
   * @return void
   */
  protected function __unset($property)
  {
    if (!property_exists($this, $property)) {
      throw new MagicMethodsException(
        "Property '$property' not defined in class " . get_class($this)
      );
    }
    else {
      $this-&gt;$property = null;
    }
  }
}

 * @copyright 2009, Juraj Seffer
 * @version $Id$
 * @access public
 */
class MagicMethodsException extends Exception
{
  /**
   * Constructor
   *
   * @param string $exception
   * @access public
   * @return void
   */
   public function __construct($exception)
  {
    throw new Exception($exception);
  }
}

Juraj Seffer | Playground » PHP

PHP Magic Methods - enforce defining of class properties