PHP
  Home arrow PHP arrow Page 4 - Using Subclasses and Accessors with Me...
Dev Shed Forums 
Administration  
AJAX  
Apache  
BrainDump  
DHTML  
Flash  
Java  
JavaScript  
Multimedia  
MySQL  
Oracle  
Perl  
PHP  
Practices  
Python  
Reviews  
Security  
Style-Sheets  
Web Services  
XML  
Zend  
Zope  
Forums Sitemap 
IBM® developerWorks 
Sun Developer Network 
E-Commerce Hosting 
Linux Web Hosting 
Managed Hosting 
Small Business Hosting 
Mobile Linux 
App Generation ROI 
VPS Hosting 
Weekly Newsletter

 
Developer Updates  
Free Website Content 
 RSS  Articles
 RSS  Forums
 RSS  All Feeds
Write For Us Get Paid 
Request Media Kit
Contact Us 
Site Map 
Privacy Policy 
Support 
 USERNAME
 
 PASSWORD
 
 
  >>> SIGN UP!  
  Lost Password? 
PHP

Using Subclasses and Accessors with Member Visibility to Protect PHP 5 Class Data
By: Alejandro Gervasio
  • Search For More Articles!
  • Disclaimer
  • Author Terms
  • Rating: 5 stars5 stars5 stars5 stars5 stars / 4
    2008-06-04

    Table of Contents:
  • Using Subclasses and Accessors with Member Visibility to Protect PHP 5 Class Data
  • Accessing private properties globally
  • Accessing private properties from a subclass
  • Retrieving the values of private properties using accessors

  • Rate this Article: Poor Best 
      ADD THIS ARTICLE TO:
      Del.ici.ous Digg
      Blink Simpy
      Google Spurl
      Y! MyWeb Furl
    Email Me Similar Content When Posted
    Add Developer Shed Article Feed To Your Site
    Email Article To Friend
    Print Version Of Article
    PDF Version Of Article
     
     
    ADVERTISEMENT


    Using Subclasses and Accessors with Member Visibility to Protect PHP 5 Class Data - Retrieving the values of private properties using accessors


    (Page 4 of 4 )

    During the previous section, you learned a simple -- yet crucial -- concept: the private properties of a class can only be accessed from inside of the class. However, it's possible to play around with this theoretical definition and develop yet another example that shows how the properties in question can be retrieved by way of an accessor method.

    To perform this task, I'm going to use the same "DataSaver" class that you saw previously, which, as you'll surely recall, does have a couple of these accessor methods. If this doesn't ring any bells, here's the signature of this class:


    class DataSaver{

    private $filePath;

    private $data;

    public function __construct($data,$filePath){

    if(!$data||strlen($data)>1024){

    throw new Exception('Invalid data for being saved to target file.');

    }

    if(!file_exists($filePath)){

    throw new Exception('Invalid target file.');

    }

    $this->data=$data;

    $this->filePath=$filePath;

    }

    // save data to target file

    public function save(){

    if(!$fp=fopen($this->filePath,'w')){

    throw new Exception('Error opening target file.');

    }

    if(!fwrite($fp,$this->data)){

    throw new Exception('Error writing data to target file.');

    }

    fclose($fp);

    }

    // get target file via an accessor

    public function getFilePath(){

    return $this->filePath;

    }

    // get data via an accessor

    public function getData(){

    return $this->data;

    }

    }


    As you can see, the above data saving class has been provided with a couple of accessors, called "getFilePath()" and "getData()" respectively. With these methods available, I'm going to create a simple script that shows how to use them in order to access the private properties of the class.

    Having said that, here's the script:


    try{

    // create new instance of 'DataSaver' class

    $dataSaver=new DataSaver('This string of data will be saved to a target file!','datafile.txt');

    // save data to target file

    $dataSaver->save();

    // print value of private properties

    echo 'Target file is the following : '.$dataSaver->getFilePath().'<br />';

    echo 'Data for being saved to target file is the following : '.$dataSaver->getData();

     

    /* displays the following

    Target file is the following : datafile.txt

    Data for being saved to target file is the following : This string of data will be saved to a target file!

    */

    }

    catch(Exception $e){

    echo $e->getMessage();

    exit();

    }


    As shown by the previous code snippet, it's perfectly possible to retrieve the values that correspond to the private properties of the "DataSaver" class by using the respective accessors. The reason is extremely simple: the methods access the properties from inside the class!

    Of course, this concept may seem pretty obvious, particularly if you have a lot of experience working with classes in PHP. But if you're just getting started using its object model, the previous example might help you understand how to work with private properties.

    Finally, with all of these code samples at your disposal, don't excuse yourself from practicing with private class properties in PHP 5!

    Final thoughts

    In this third episode of the series I concluded this quick overview of working with public, protected, and private class properties. Nonetheless, I'm only scratching the surface when it comes to exploring the advantages of using member visibility in PHP 5; the language permits you to use this same feature with the methods of a class as well. Thus, in the upcoming article, I'll explain how to implement this handy feature in several class methods.

    Now that you've been warned about the subject of the next part, you can't miss it!


    DISCLAIMER: The content provided in this article is not warranted or guaranteed by Developer Shed, Inc. The content provided is intended for entertainment and/or educational purposes in order to introduce to the reader key ideas, concepts, and/or product reviews. As such it is incumbent upon the reader to employ real-world tactics for security and implementation of best practices. We are not liable for any negative consequences that may result from implementing any information covered in our articles or tutorials. If this is a hardware review, it is not recommended to open and/or modify your hardware.

       · This third chapter of the series demonstrates with some approachable examples how...
     

       

    PHP ARTICLES

    - Using Aliases and the Autoload Function with...
    - Authentication Scripts for a User Management...
    - Utilizing the Use Keyword for Namespaces in ...
    - Building a User Management Application
    - Working With Different Namespaces in PHP 5
    - User Management Explained: Overview
    - Using Namespaces in PHP 5
    - Building a Modular Exception Class in PHP 5
    - Database and Password Security for Web Appli...
    - Handling MySQL Data Set Failures in PHP 5
    - Building Site Registration for Web Applicati...
    - Intercepting Customized Exceptions in PHP 5
    - Sub Classing Exceptions in PHP 5
    - Building a Content Management System with Co...
    - Filters and Login Systems for Web Applicatio...

     
    Application Delivery: Everything You Wanted to Know, but Didn`t Know You Needed to Ask
    A comprehensive guide to examining the topics of Wide-area Data Services and app....

     
    Best Practices: Safe and Secure Hardware Asset Recovery
    Companies increasingly must meet EPA and local requirements for the disposal of ....

     
    Managing SSL Security in Multi-Server Environments
    Read this white paper to learn how to simplify management of your organization's....

     
    Open Source Security Myths
    Open Source Software (OSS) is computer software whose source code is available t....

     
    Power and Cooling Capacity Management for Data Centers
    This paper describes the principles for achieving power and cooling capacity man....

     




    © 2003-2008 by Developer Shed. All rights reserved. DS Cluster 5 hosted by Hostway
    Stay green...Green IT