Get instances to arbitrary plugins in php files - php

Question

The name is quite bad, but I really don't know what else to call it.
I'm trying to make a extendable and modular plugin system for my website. I need to be able to access plugin php files that exist in a plugin directory and get access to their classes to call functions such as getting the html content that the plugin should show and more.
Below is a semi-pseudo code example of what I am trying to achieve, but how to actually arbitrarily load the plugins is where I am stuck (PluginLoader.php).
-Max
//BasePlugin.php
abstract class BasePlugin
{
public function displayContent()
{
print "<p>Base Plugin</p>";
}
};
//ExamplePlugin.php -> In specific plugin directory.
require('../BasePlugin.php');
class ExamplePlugin extends BasePlugin
{
public static function Instance()
{
static $inst = null;
if ($inst === null) {
$inst = new ExamplePlugin();
}
return $inst;
}
public function displayContent()
{
print "<p>Example Plugin</p>";
}
}
//PluginLoader.php
foreach($pluginFile : PluginFilesInDirectory) { // Iterate over plugin php files in plugin directory
$plugin = GetPlugin($pluginFile); // Somehow get instance of plugin.
echo plugin->displayContent();
}

Answer 1

I'm guessing here, but it seems to me that you need to:
get a list of the plugins in the desired directory.
include or require the plugin's class file.
create an instance of the class.
call the plugin's displayContent() method.
So, you probably want to do something like
$pluginDir = 'your/plugin/directory/' ;
$plugins = glob($pluginDir . '*.php') ;
foreach($plugins as $plugin) {
// include the plugin file
include_once($plugin) ;
// grab the class name from the plugin's file name
// this finds the last occurrence of a '/' and gets the file name without the .php
$className = substr($plugin,strrpos($plugin,'/') + 1, -4) ;
// create the instance and display your test
$aPlugin = $className::Instance() ;
$aPlugin->displayContent() ;
}
There's probably a cleaner way to do it, but that will ready your directory, get the plugins' code, and instantiate each one. How you manage/reference them afterwards depends on how your plugins register with your application.