PHP Output Buffer Manager

February 10th, 2014 at 06:17

With rebuilding my website with WordPress, I have made progress on the WordPress starter theme I’ve been working on. One thing I used for it was PHP’s output buffering to control output and allow me to define “blocks” of content, then render them at a later point in their proper location. To this end, I created some helper methods to manage this for me and allow easy creating of named buffers. I got the idea for this from the slots of Symfony’s PHP templating engine.

I have since broken this out of my WordPress theme helper classes into its own class and created a github repo, PHP-BufferManager to allow its use for generic purposes. This is a very simple repo and class. The most common way to use it would be to use $instance->start('name'); to start a buffer named ‘name’ and $instance->end(); to end it, then $instance->get('name'); at a later point to get the string value of the buffer for output or other purposes. A simple example:

<?php
$bufferManager = new TJMComponentBufferManagerBufferManager();

$bufferManager->start('block1');
echo 'This is in block 1';
$bufferManager->end();

$bufferManager->start('block2');
echo 'This is in block 2';
?>
<div class="wrapper">
    <h2>This is block 1's heading</h2>
    <div class="block1">get('block1'); ?></div>
    <h2>This is block 2's heading</h2>
    <div class="block2">get('block2'); ?></div>
</div>

Or:

<?php
$bufferManager->start('main');
include($mainContentFile);
$bufferManager->end();
$bufferManager->start('aside');
include($asideContentFile);
$bufferManager->end();

if($isAjaxRequest){
    echo json_encode(Array(
        'title'=> $pagetitle
        ,'main'=> $bufferManager->get('main')
        ,'aside'=> $bufferManager->get('aside')
    ));
}else{
?>
<!DOCTYPE html>
<html>
    <title><?=$pagetitle?></title>
    …
    <main><?=$bufferManager->get('main')?></main>
    <aside><?=$bufferManager->get('aside')?></aside>
    …
</html>
<?php }

In the case of my WordPress theme, WordPress loads files representing the content of a page, and you call get_header(); at the top and get_footer(); at the bottom, which include the theme’s header.php and footer.php respectively. I wanted to be able to have the entire wrapper/skeleton in one file instead of split into two. So I use output buffering. In my header.php, I start a buffer:

<?php
// {theme}/header.php
$tjmThemeHelper->buffers->start('main');

Then in my footer I end the buffer and include the wrapper/skeleton file:

<?php
// {theme}/footer.php
$tjmThemeHelper->buffers->end('main');
require('./skeleton.php');

The skeleton file then can define the entire document wrapper and output the content of the file representing the main content where it pleases:

<!DOCTYPE html>
<html <?php language_attributes(); ?>>
    …
    <title><?php echo wp_title('-', false, 'right') .  get_bloginfo('name'); ?></title>
    …
<?php
//--main with wrapper
if($tjmThemeHelper->buffers->has('main')){
?>
    <main class="siteMainWrap" id="main" role="main">
        <div class="siteMain" id="mainContent">
            <?=$tjmThemeHelper->buffers->get('main'); ?>
        </div>
    </main>
<?php
}

//--aside/sidebar
if($tjmThemeHelper->buffers->has('aside')){
    echo $tjmThemeHelper->buffers->get('aside');
}
?>
</html>

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