In the world of objects, encapsulation is a popular term. But sometimes we never pay enough attention to properly declare the access type of instance variables. Yes, I mean to say in terms of design and class architecture perspective. The basic advantage of object oriented programming is code re-usability. Meaning, using your class in a different program or changing your class shall not affect any other parts of code, which uses it. Now, if most of your instance variables are public and if (say) several other classes extends your class, or use its objects, then if any day you want to change the behavior of that instance variables, then all those codes will require re-work. Like say, if you want to ensure that the instance variables should have a value range and it will not accept any value outside that range.

Consider a class automobile with an instance variable no_of_wheels. Will you allow any other code to assign a value of fraction or a negative value to the member variables? It is better to declare the variable as private and use getter and setter method to control the assignment behavior. Only in this way you can achieve the truest meaning of encapsulation. Here is the pseudo code example.

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Class Automobile {
 
    private int no_of_wheels;
 
    public setWheels(int wheel_num) {
 
      this.no_of_wheels = wheel_num; //setting value to the class variables.
 
      if(this.no_of_wheels < 0) {
 
         this.no_of_wheels = 0 - this.no_of_wheels;
 
      }
 
   }
 
   public getWheels() {
 
     return this.no_of_wheels;
 
  }
 
}

I know, the question in your mind is then shall I not declare any member variable as public. Sure, you can  but ensure that it can have any range of values. If the type is boolean then safely, it can be a candidate of public access type. But I prefer keeping things private.

Please let me know if I am wrong.

A small code snippet, which is very common yet useful. Let’s write a function which will copy a folder/directory and its contents (including subfolders, files) from one place to other.

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public static function copyFolder($source,$dest) { // recursive function
   if(is_dir( $source)) { // if its directory
           @mkdir($dest); //make it
           $d = dir($source); // create directory object
           while(FALSE!==($entry=$d->read())) { // read each file of directory
               if($entry=='.' || $entry == '..') { //exclude root and parent
                  continue;
               }
              $newentry = $source . '/' . $entry;  // get sub
              if(is_dir($newentry)) { // if sub is directory
                  self::copyFolder($newentry,$dest.'/'.$entry); // then go recursive
                  continue;
              }
              copy($newentry, $dest.'/'.$entry ); //else copy file
           }
           $d->close();
        }
        else {
          copy($source,$dest); // copy file
        }
  }

I hope this code will be a helpful contribution. Please do let me know.

As a open source programmer, I have used several classes or codes widely available over the internet. I was thinking to contribute some of my knowledge as well. So, I decided to contribute on regular basis classes to phpclasses repository. Here are two of my contributions.

WEB EXPLORE 1.0

This package is about displaying folders and files in windows explorer style. Basically, I was learning observer-observable design pattern and somehow extended the pattern to produce this application. Since I am a very good designer, the package interface is horrible to get. Basically, you need a lot of work to get it a decent look. Regarding the class, I tried my best to keep it flexible enough for modification. You can do anything with the code as it is completely free.

GET THE WEBEXPLORE 1.0 HERE.

YAHOO BOSS SEARCH

This package uses Yahoo Boss Search API to display web and image search result. In this package too, you will experience my design skill. It’s not poor, it’s not worst, it’s simply terrible. I hope you won’t mind that and will change the design while using the class. I also tried to put an ajax example using jquery.

GET YAHOO BOSS SEARCH 1.0.1 HERE

Alternative PHP Cache is a PECL extension, which can be utilized for many purposes. The best thing is that it can check if a file has been modified on every request. Rasmus Lerdorf (you should know the name if you are a PHP guy) who was also a pioneer in the extension development, came up with a classic example.

The example is available in http://progphp.com/progress.php and you can view the source code here. This code example uses YUI code library for presentation layer and JSON for data transfer. apc_fetch function is being used to get the status from the cache. To use it fully all you need to do is to install PECL and this extension in your system. The rest is pure magic.

I came across the timeline project of SIMILE and found that it is simply wonderful. This project creates a band of time and date of events. I found that this project can be used to create historical time period mapping with important dates and events. Creating GANTT chart for project management software will be a cakewalk if the code base is used. Practically this project can be used in several areas. I am going to explore it. What about you?