让 WordPress 主题支持侧边栏切换

// 侧边栏数量, 默认为单侧边栏
$options['sidebar'] = 1;

// 获得最新提交的值
$options['sidebar'] = $_POST['sidebar'];

<select name="sidebar" size="1">
	<!-- 单侧边栏 -->
	<option value="1" <?php if($options['sidebar'] != 2) echo ' selected '; ?>><?php _e('Single', 'classic'); ?></option>
	<!-- 双侧边栏 -->
	<option value="2" <?php if($options['sidebar'] == 2) echo ' selected '; ?>><?php _e('Double', 'classic'); ?></option>
</select>
 <?php _e('sidebar(s)', 'classic'); ?>.

// Widgets
$options = get_option('classic_options');
 
// 单侧边栏
if(function_exists('register_sidebar') && $options['sidebar'] == 1) {
	register_sidebar(array(
		'name' => 'Sidebar_single',
		'before_widget' => '<li id="%1$s" class="widget %2$s">',
		'after_widget' => '</li>',
		'before_title' => '<h3>',
		'after_title' => '</h3>'
	));
 
// 双侧边栏
} else if(function_exists('register_sidebar') && $options['sidebar'] == 2) {
	register_sidebar(array(
			'name' => 'Sidebar_bottom',
			'before_widget' => '<li id="%1$s" class="widget %2$s">',
			'after_widget' => '</li>',
			'before_title' => '<h3>',
			'after_title' => '</h3>'
	));
	register_sidebar(array(
			'name' => 'Sidebar_top',
			'before_widget' => '<li id="%1$s" class="widget %2$s">',
			'after_widget' => '</li>',
			'before_title' => '<h3>',
			'after_title' => '</h3>'
	));
}

<ul class="sidebar_1">
	<?php if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar('sidebar_single') ) : // single ?>
 
		<?php if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar('sidebar_top') ) : // top ?>
<!-- TODO: 顶部侧边栏内容 -->
		<?php endif; // top ?>
 
		<?php if ($options['sidebar'] >= 2) : ?>
</ul>
<ul class="sidebar_2">
		<?php endif; ?>
 
		<?php if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar('sidebar_bottom') ) : // bottom ?>
<!-- TODO: 底部侧边栏内容 -->
		<?php endif; // bottom ?>
 
	<?php endif; // single ?>
</ul>