Plugin System in php

api.php

<?php
class Api {
  public function call($o) {
    echo $o."<br>\n";
  }
}

example_Plugin.php

<?php

return 'ExamplePlugin';
class ExamplePlugin extends TB_Plugin {
  public function ExamplePlugin($api) {
    parent::__construct($api);
  }

  public function call() {
    $this->api->call('Called from ExamplePlugin');
  }

  public function whatever() {
    echo "Doing whatever from ExamplePlugin<br>\n";
  }
}

helloworld_Plugin.php

<?php

return 'HelloWorldPlugin';
class HelloWorldPlugin extends TB_Plugin {
  public function HelloWorldPlugin($api) {
    parent::__construct($api);
  }

  public function call() {
    $this->api->call('Hello world from HelloWorldPlugin');
  }
}

index.php

<?php
require_once('pluginManager.php');
require_once('api.php');

$pm = new PluginManager(new Api());

foreach (glob('./*_Plugin.php') as $file) {
  $pm->registerPlugin(require_once($file));
}

echo "<b>Call:</b><br>\n";
$pm->doCall();

echo "<br><br><b>Whatever:</b><br>\n";
$pm->doWhatever();

plugin.php

<?php

abstract class TB_Plugin {
  protected $api;

  public function TB_Plugin($api) {
    $this->api = $api;
  }

  public function call() {}
  public function whatever() {}
}

pluginManager.php

<?php
require_once('api.php');
require_once('plugin.php');

class PluginManager {
  private $pluginList; // TB_Plugin[]
  private $api;

  public function PluginManager($api) {
    $this->pluginList = [];
    $this->api = $api;
  }

  public function registerPlugin($plugin) {
    $this->pluginList[$plugin] = new $plugin($this->api);
  }

  public function doCall() {
    foreach ($this->pluginList as $pluginName => $plugin) {
      echo "(Executing whatever on plugin: ".$pluginName.")<br>\n";
      $plugin->call();
    }
  }

  public function doWhatever() {
    foreach ($this->pluginList as $pluginName => $plugin) {
      echo "(Executing whatever on plugin: ".$pluginName.")<br>\n";
      $plugin->whatever();
    }
  }
}