basic widget

<?php
/*
Plugin Name: Week 2 Assignment Widget
Plugin URI: http://p2pu.org/webcraft/wordpress-development
Description: Week 2 Assignment Widget
Version: 1.0
Author: nunomorgadinho
Author URI: http://p2pu.org/webcraft/wordpress-development
*/

function widget_assign($args) {
    extract($args);
?>
        <?php echo $before_widget; ?>

        <div class="week2assign">
        <span></span><h2>Tribes that I belong:</h2>
        <ul>
         <?php
        $tribes = get_option('widget_assign');

        if (is_serialized($tribes['tribes'])) {
            $tribes['tribes'] = unserialize($tribes['tribes']);
        }

        // you can use this for debugging purposes
      //  print_r($tribes['tribes']);

        $tribes_instances = $tribes['tribes'];
        for ($i = 0; $i < count($tribes_instances); $i++)
        {
            $val = $tribes_instances[$i];
            $val = str_replace("\\", "", $val);
            echo '<li class="'.$val.'">'.$val.'</li>';
        }

        ?>
        </ul>
        </div>

        <?php echo $after_widget; ?>
<?php
}

function widget_assign_control() {

?>
        Select which tribes do you belong :
        <br/><br/>

        <?php
        $tribes = array("Hackers", "Developers", "Entrepreneurs", "Designers");

        $checked = '';
        foreach ($tribes as $i)
        {
            if (is_tribe_selected($i)) {
                $checked = 'checked';
            }
            echo '<input type="checkbox" name="tribes[]" '.$checked.' value="'.$i.'">'.$i.'</input><br/>';
            $checked = '';
        }

        $data['tribes'] = serialize($_POST['tribes']);
        update_option('widget_assign', $data);
}


function is_tribe_selected($tribe)
{
    $tribes = get_option('widget_assign');

    if (is_serialized($tribes['tribes'])) {
        $tribes['tribes'] = unserialize($tribes['tribes']);
    }

    $tribes_instances = $tribes['tribes'];
    for ($i = 0; $i < count($tribes_instances); $i++)
    {
        $val = $tribes_instances[$i];
        $val = str_replace("\\", "", $val);
        if ($val == $tribe)
            return true;
    }

    return false;
}

register_sidebar_widget('Week 2 Assign', 'widget_assign');
register_widget_control('Week 2 Assign', 'widget_assign_control');

?>