A great to way to share your PHP code with visitors is to display it directly in the browser with automatically generated syntax highlighting. Here is a screenshot showing an example of syntax-highlighted PHP code:

Displaying your PHP scripts in syntax-highlighted form is an excellent way to share source code details directly with your readers. Rather than zipping the script and requiring users to download, unzip, and open the file in an editor, displaying your code directly saves you and your visitors time, effort, and hassle. Plus, in my opinion, looking at syntax-highlighted PHP code is a beautiful sight, day or night ;)

In this article, we will explore 5 different ways to display the syntax-highlighted source of your PHP scripts. Three of the methods are designed to highlight entire files, and the other two are aimed directly at highlighting individual strings of PHP code. All of these methods employ PHP’s built-in syntax highlighter.

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Beautiful Source-Code Output, Part 1: Whip your WordPress RDF Code into Submission

Update: This article applies specifically to WordPress 2.0.2, but may be generalized to any WP 2.0+ version.

I love looking at beautiful source-code output. However WordPress tends to spit code out in random chunks, often leaving spaces, line breaks, and tabs littered throughout the source output. This messes things up. Lists don’t look like lists and logically written code often appears scattered along the page carelessly. Often, this is the result of poorly written PHP, which can be manipulated to write beautifully aligned code that looks as good as it works.

For the first article in this series, we will bring order to the typical RDF chaos that WordPress spits out by default. To see an example of this, check out this source code, taken directly from the output of a default installation of WordPress. Notice how the awkward chunk of code leans, strangely enough, to the right. This type of RDF-code output seems to be the norm for WordPress users who have enabled that particular feature.

Okay, so it looks hideous, and we want to clean it up and make it shine. First thing to do is backup everything, even your database. Don’t trip though — this is a simple “cut-and-paste” procedure, but it is always a good idea to have a recent backup of your data just in case. Next, open the file wp-includes/comment-functions.php and find the function trackback_rdf, which is located about halfway down the page on line #525 (#509 for WP 2.0). Now, replace the following block of PHP code:

function trackback_rdf($timezone = 0) {
	global $id;
	if (!stristr($_SERVER['HTTP_USER_AGENT'], 'W3C_Validator')) {
	echo '<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" 
	    xmlns:dc="http://purl.org/dc/elements/1.1/"
	    xmlns:trackback="http://madskills.com/public/xml/rss/module/trackback/">
		<rdf:Description rdf:about="';
	the_permalink();
	echo '"'."\n";
	echo '    dc:identifier="';
	the_permalink();
	echo '"'."\n";
	echo '    dc:title="'.str_replace('--', '&#x2d;&#x2d;', wptexturize(strip_tags(get_the_title()))).'"'."\n";
	echo '    trackback:ping="'.trackback_url(0).'"'." />\n";
	echo '</rdf:RDF>';
	}
}

with our new and improved version¹:

function trackback_rdf($timezone = 0) {
	global $id;
	if (!stristr($_SERVER['HTTP_USER_AGENT'], 'W3C_Validator')) {
	echo '<rdf:RDF ';
	echo "\n";
	echo '   xmlns:dc="http://purl.org/dc/elements/1.1/" ';
	echo "\n";
	echo '   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" ';
	echo "\n";
	echo '   xmlns:trackback="http://madskills.com/public/xml/rss/module/trackback/">';
	echo "\n";
	echo '<rdf:Description ';
	echo "\n";
	echo '   dc:creator="';
	the_author();
	echo '" '."\n";
	echo '   dc:date="';
	the_date_xml();
	echo ' @ ';
	the_time('g:i a');
	echo '" '."\n";
	echo '   dc:title="'.str_replace('--', '&#x2d;&#x2d;', wptexturize(strip_tags(get_the_title()))).'" '."\n";
	echo '   rdf:about="';
	the_permalink();
	echo '" '."\n";
	echo '   dc:identifier="';
	the_permalink();
	echo '" '."\n";
	echo '   trackback:ping="'.trackback_url(0);
	echo '" '."\n";
	echo '   dc:description="';
	the_excerpt_rss();
	echo '" />'."\n";
	echo '</rdf:RDF>';
	}
}

Finally, open your WordPress theme’s “index.php” file, find the loop, and add an echoed line break to the commented-out RDF function. Your code should now look like this:

<!--
<?php trackback_rdf(); ?>
<?php echo "\n"; ?>
-->

That’s it — save the two files, upload them, refresh your pages, and check the RDF output in the source code. If all goes well, your RDF code should now resemble this:

<!--
<rdf:RDF 
   xmlns:dc="http://purl.org/dc/elements/1.1/" 
   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" 
   xmlns:trackback="http://madskills.com/public/xml/rss/module/trackback/">
<rdf:Description 
   dc:creator="Perishable" 
   dc:date="2006-02-22 @ 11:19 am" 
   dc:title="WordPress RDF Source Makeover" 
   rdf:about="http://perishablepress.com/press/?p=49" 
   dc:identifier="http://perishablepress.com/press/?p=49" 
   trackback:ping="http://perishablepress.com/press/wp-trackback.php?p=49" 
   dc:description="Beautiful Source-Code Output, Part 1: Whip your WordPress RDF Code into Submission
I love looking at beautiful source-code output. [...continued &#187;]" />
</rdf:RDF>
-->

Now that’s much better!

Next time we will look at constructing righteous headings and pimping them for excellence on planet source-code output.

Update: To gain greater control over your WordPress RDF source-code output, replace the native function, the_excerpt_rss(); (located near the last line of the trackback_rdf() function), with the more flexible function, the_content_rss. This function provides five parameters as described in the WordPress Codex:

<?php the_content_rss('more_link_text', strip_teaser, 'more_file', cut, encode_html); ?>

More specifically, here is how we use the function to limit the number of words output in the dc:description attribute, thus optimizing bandwidth while preventing unruly code examples from disrupting document structure (as in the case of JavaScript comments):

the_content_rss('', TRUE, '', 7, 2);

Fin

References

• ¹ Download the replacement code here