system/classes/plugin.php

<?php
namespace Habari;

abstract class Plugin extends Pluggable
{

  final public function info()
  {
    static $info;
    if ( !isset( $info ) ) {
      $info = Plugins::load_info( $this->get_file() );
      if ( isset( $info->help ) ) {
        Plugins::register( array( $this, '_help_plugin_config_plugin' ), 'filter', 'plugin_config:' . $this->plugin_id(), 8 );
        Plugins::register( array( $this, '_help_plugin_ui_plugin' ), 'action', 'plugin_ui:' . $this->plugin_id(), 8 );
      }
    }
    return $info;
  }

  final public function __construct()
  {
    parent::__construct();
  }

  public function _help_plugin_config_plugin( $actions, $plugin_id )
  {
    if ( $plugin_id == $this->plugin_id() ) {
      foreach ( $this->info->help as $help ) {
        $name = (string)$help['name'];
        if ( $name == '' ) {
          $name = '_help';
        }
        // @locale Displayed as an icon indicating there is help text available for a plugin.
        $actions[$name] = _t( '?' );
      }
    }
    return $actions;
  }

  public function _help_plugin_ui_plugin( $plugin_id, $action )
  {
    if ( $plugin_id == $this->plugin_id() ) {
      foreach ( $this->info->help as $help ) {
        if ( ( $action == (string)$help['name'] && (string)$help['name'] != '' ) || ( $action == '_help' && (string)$help['name'] == '' ) ) {
          echo '<div class="help">' . ( (string)$help->value ) . '</div>';
        }
      }
    }
  }

  public function get_version()
  {
    return (string)$this->info->version;
  }
}

?>