要对嵌套标题使用不同的回调，请在pricing_box 在返回字符串之前，回调并还原主处理程序。

add_shortcode( \'pricing_box\', \'shortcode_pricing_box\' );
add_shortcode( \'heading\',     \'shortcode_heading_main\' );

function shortcode_pricing_box( $atts, $content = \'\' )
{
    // switch shortcode handlers
    add_shortcode( \'heading\', \'shortcode_heading_pricing_box\' );

    $out = \'<div class="pricing-box">\' . do_shortcode( $content ) . \'</div>\';

    // restore main handler
    add_shortcode( \'heading\', \'shortcode_heading_main\' );

    return $out;
}

function shortcode_heading_main( $atts, $content = \'\' )
{
    return "<h2>$content</h2>";
}

function shortcode_heading_pricing_box( $atts, $content = \'\' )
{
    return "<h3>$content</h3>";
}