Small Program Blog

In WordPress, there are widgets such as calender that may appear on your theme based on your appearance setting. Usually they will appear on sidebar when you add the widgets in the theme. If there is no widget adding to the sidebar, a function dynamic_sidebar() will return a FALSE value. This function is useful if you are designing a theme template because you may want to create something if there is no widget on the sidebar. For example, you may want to include your own widget to the sidebar if user has not included any widget in the theme appearance setting.

Further, if you want to add widget at the appearance setting, you will need to register the sidebar to WordPress in the file function.php. The function register_sidebar() will tell the plugin that your theme will need exactly one sidebar and your admin inteface should have Sidebar Widgets in the Presentation menu. register_sidebar() also allows you to decorate the widget by adding a parameter to it. For example,

<?php
if (function_exists(’register_sidebar’) )
register_sidebar(array(’before_widget’=>’ ‘,
‘after_widget’ => ‘ ‘,
‘before_title’ => ‘<div class=”title”>’,
‘after_title’=>’</div>’));
?>

before_widget and after_widget means that something that you want to decorate the widget.. you may think it can be a warper and you will warp your widgets. In this example, we put nothing, so there is no decoration for this widget warper. Then before_title and after_title, will decorate the wiget title with <div lass=”title”> and </div>. The output will look like this:

<div lass=”title”> Widgets Title </div>

What if you want to include more than one sidebar? Then instead of using register_sidebar(), you will use register_sidebars(n) where n is the number of sidebars. (starting with 1)

For more information, you may check out this page to see how to widgetizing themes with sidebar.
http://codex.wordpress.org/Widgetizing_Themes