Creating a complete basic PHP Modules / Plugin System

Well Everyone needs a PHP Plug-in system if you want to keep up to date and stop modifying loads of code every time you get a new idea for your website. In this tutorial I will show you how to create a sweet and easy PHP Plug-in/Modules System.

What you Will Learn

How to Dynamically Load Plugins
The basics of OO PHP

Pre-Requisites

Basic Knowledge of PHP
An understanding of File Directory structures

What does OO Mean?
OO Means Object Orientated. This is the use of classes to control the way your PHP Script works. It is used mainly to recycle code and keep things much easier to read.

Example 1.
We have a class called HelloWorld.class.php It contains the following functions :
hello()
world()
__construct()

The __construct() Function will be called no matter what after we initiate our class as it is the constructor function of the class. Now lets look how the code will look for HelloWorld.class.php


<?php

     

  class HelloWorld {


     function __construct() { //Our construct function

         print "HelloWorld Class has been constructed <br />"; // This will print when we define our class

     }


     function hello() { // this is the hello() function

         print "Hello"; //Print Hello when we call this function

     }


     function world() { // Finally the world() function

        print " World"; //Prints World

     }


  }


?>

Now this is how a class gets called. It is fairly simple


<?php


include_once('HelloWorld.class.php'); // Include our class


$HelloWorld = new HelloWorld; //Load our class into a variable


$HelloWorld->hello(); // Say Hello!!

$HelloWorld->world(); // Say  World


?>

This will output the following


HelloWorld Class has been constructed 

Hello World

Simple Huh?

Now onto our plugin system.

The Module System Directory Structure
Well its really upto you how you lay it out. this is how I will be doing it for this guide.


<WebRootDir>

      |

      + module.php (This will be the file we call the modules from

      |

      + modules (dir)

           |

           + HelloWorld

           |      + HelloWorld.module.php

Now Lets Start some serious coding :)

Lets start with modules.php since it will be the largest file. We will be using $_GET variables to access modules. E.G yoursite.com/modules.php?module=HelloWorld

Now I assume you have already setup your php tags if not create a new file modules.php and add the PHP Tags.

Now we will use the Variable $_GET['module'] and assign it to a variable $module for ease of use. I will also setup some configuration variables for ease of use.


<?php


$module = $_GET['module'];


// Configuration \\

$module_base_dir = './modules/'; //Directory of modules (You can use absolute path)

$module_ext = '.module.php'; // Our Module Extension

$module_base_file = $module.$module_ext; // So this will show HelloWorld.module.php



// DO NOT EDIT BELOW THIS LINE UNLESS YOU ARE CONFIDENT IN PHP \\


DEFINE('IS_IN_MODULE', true); //Define that this is the module controller


if(!isset($module))

{

    die("No Module Selected!!");

}


?>

The IF statement I added was just to check a module was selected. Now we need a way to check if the module file and directory exist. We use the file_exists() function to do this.

Add the following after the if statement in the last snippet


if(file_exists($module_base_dir.$module. '/' .$module_base_file))

{

    if(isset($_GET['function'])) //Check if we have defined a function

    {

        $function = $_GET['function']; //Assign the function to a variable

    }

    else

    {

        $function = 'index'; // if no function assign function index

    }

    include($module_base_dir.$module. '/' .$module_base_file); // Include our module

    $moduleClass = new $module; // This Will launch our plugin constructor.

    if(method_exists($moduleClass, $function)) // Check our function exists

    {

        $moduleClass->$function(); //Call the function defined above

    }

    else

    {

        die("Function not found!"); // Show error message

    }

}

else

{

   die("Module Not Found!!");

}

now thats our module.php file lets create our modules.

In the modules folder create a new folder called HelloWorld inside that make a HelloWorld.module.php file. This will be our main module class. Make sure the class name matches the Case of the module name.


<?php

if(!defined('IS_IN_MODULE')) { die("NO DIRECT FILE ACCESS!"); }


class HelloWorld {


    function index() // This is our index function. It is called if we do not have a function defined

    {

        print("HelloWorld Module from Keiran's Module System");

    }

    

    function hello() // hello function called from modules.php?module=HelloWorld&function=hello

    {

        print("hello");

    }

    

    function world() // hello function called from modules.php?module=HelloWorld&function=world

    {

        print("world");

    }


}


?>

Download Source : thttp://keiran-smith.net/moduletutfiles.zip

if you use the files be sure to give me some credit :)