php - Call External Object in Class Function During Callback -

i've class has function check , creates table in database. in order need use wordpress $wpdb object.

i need function run on first plugin activation, use function:

register_activation_hook  ( __file__, array( 'memorialcandles', 'dbinstall'   ) ); 

the problem error:

fatal error: using $this when not in object context in /home/xxx/xxx/wordpress/wp-content/plugins/memorialcandles/memorial-candles.class.php on line 77

the class code:

<?php  // global variables: global $wpdb; register_activation_hook  ( __file__, array( 'memorialcandles', 'dbinstall'   ) );  /**  * class: memorialcandles  *   * provides skeleton plugin , handles queries , action.  *   * @author dor zuberi <dor@zubri.me>  * @copyright 2011 dor zuberi  * @license http://www.php.net/license/3_01.txt  */ class memorialcandles {     // variables         /**      * @var string stores plugin direction - rtl or ltr.      */     private $plugindirection;      /**      * @var string stores plugin database table name.      */     private $tablename;      // constructor     /**      * initiates plugin, stores , configure basic setup procedures.      *       * @return void      */     function __construct()     {         global $wpdb;          $this->tablename = $wpdb->prefix . 'memorialcandles';     }      // getters      // setters      // methods     /**      * handles database table creation.      *       * @return void      */     function dbinstall()     {         global $wpdb;          if( $wpdb->get_var( "show tables `{$this->tablename}`" ) != $this->tablename )         {             $sql = "create table `{$this->tablename}` (                         id        int(8) not null auto_increment,                         fullname  text   not null,                         message   text   not null,                         postdate  text   not null,                         galleryid int(8) not null,                          unique key id(id)                     );";              require_once( abspath . 'wp-admin/includes/upgrade.php' );             dbdelta( $sql );         }     }      /**      * handles database table drop procedure.      *       * @return void      */     function dbuninstall()     {         global $wpdb;          $sql = "drop table if exists `{$this->tablename}`;";          $wpdb->query( $sql );     }     }  ?> 

thanks in advance! :d

to use instance method in callback, callback needs instance. you'll either need create instance call register_activation_hook:

register_activation_hook(__file__, array(new memorialcandles(), 'dbinstall')); 

or make dbinstall class method.

class memorialcandles {     // variables         /**      * @var string stores plugin database table name.      */     private static $tablename, $tablesuffix = 'memorialcandles';     ...      // methods     /**      * handles database table creation.      *       * @return void      */     static function dbinstall() {         global $wpdb;         $tablename = self::$tablename = $wpdb->prefix . self::$tablesuffix;         if( $wpdb->get_var( "show tables `{$tablename}`" ) != $tablename )         {             $sql = "create table `{$tablename}` (                         id        int(8) unsigned not null auto_increment,                         fullname  text   not null,                         message   text   not null,                         postdate  text   not null,                         galleryid int(8) unsigned not null,                          unique key id(id)                     );";              require_once( abspath . 'wp-admin/includes/upgrade.php' );             dbdelta( $sql );         }     }     ... }