Finding Exact Information on WordPress Functions

According to my motto:

‘Knowledge is Knowing where it is Written’
by Albert Einstein

– I like to look up the core files of WordPress where the functions are defined.

What I quite often do when I come across something new or not fully understood – a function, or template tag, or whatever wordpress related:

I search the web for it; not just with any keywords, but quite focussed.

Lets take the example of one of my earlier posts (Front Page Comments on your WordPress Blog) where I was investigating why comments don’t easily show on the front page or on archive pages of a blog:

The function in the template files that would show comments and the comment form, is ‘comments_template()’ – I therefore search for:

‘function comments_template()’

the search engine of my choice returns (apart from many other links) first of all the link to the documentation in the codex; and a link to the core file (and the exact line):

Obviously, my search engine knows me, so the relevant results show quite at the top of all possible search results; you may need to scroll down a few pages to find the important link: the one beginning with ‘PHPXRef’.

the link to follow is:

in the page that opens, you’ll get the line:
defined at: followed by a link.

click on that link;

that leads you to:

with a list of some functions; click on the title of the one you are looking up.

in there in line 851, you have it (the code that explains why comments do not automatically show on the front page; and what you can do to make them show):

851      if ( !(is_single() || is_page() || $withcomments) || empty($post) )

This search method is also great for finding related functions, global wordpress variables, and expanding your vocabulary and understanding of wordpress terms…

Changing the ‘Read more’ in Twenty Ten Child Theme

To change the ‘read more’ text in a child theme of Twenty Ten, one needs to add a few lines to functions.php of the child theme.

This procedure uses a method that I came across in an introductory article about programming a child theme of Twenty Ten, by Aaron Jorbin, who himself was building upon Mangling strings for fun and profit, by WordPress lead Developer Peter Westwood.

class Transformation_Text_Wrangler {
function reading_more($translation, $text, $domain) {
$translations = &get_translations_for_domain( $domain );
if ( $text == 'Continue reading <span class="meta-nav">&rarr;</span>' ) {
return $translations->translate( 'Get to know more <span class="meta-nav">&raquo;</span>' );
return $translation;
add_filter('gettext', array('Transformation_Text_Wrangler', 'reading_more'), 10, 4);

This way of customising texts in a child theme is applicable to all the strings of the mother theme.

Alternating Posts Backgrounds for Twenty Ten

This is a short instruction how to add alternating styles to the post on the front page and in the archives of the wp3 default theme.

Edit loop.php of Twenty Ten, and locate:

<?php /* How to display all other posts */ ?>
<?php else : ?>
<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>

Change this to:

<?php /* How to display all other posts */ ?>
<?php else : ?>
<?php $stripe = ($stripe == 'dark') ? 'bright' : 'dark'; ?>
<div id="post-<?php the_ID(); ?>" <?php post_class($stripe); ?>>

This will add the css classes .dark and .bright to the post classes.

To brighten it up, add these new formats to style.css (with a harmonious choice of your own color codes):

.dark { background-color: #3f6; }
.bright { background-color: #fc3; }


This coding is not limited to TwentyTen – you can use it in any loop as long as the theme utilizes the post_class().
The switcher part is:

<?php $stripe = ($stripe == 'dark') ? 'bright' : 'dark'; ?>

And the merging of the new class with post_class() is:

<?php post_class($stripe); ?>

Image Rotator for the Header of Twentyten

The wp3 default theme TwentyTen comes with a choice of header images, which can be selected from the dashboard.
To rotate these images to show randomly in the header, we can make use of the global array variable which stores all the default header image information: $_wp_default_headers.

The rest is easy: we build a function, which we later save in functions.php of TwentyTen, to pick a random image out of the available images:

function rotate_default_headers() {
global $_wp_default_headers;
$rnd_header = rand( 1,count($_wp_default_headers));
$header_nr = 1;
foreach( $_wp_default_headers as $heady ) :
if ( $header_nr == $rnd_header ) {
echo get_bloginfo('template_url') . substr( $heady['url'], 2 );

to show the randomly rotated images in the header, add the function call in header.php –
simply edit header.php, and find this line:

<img src="<?php header_image(); ?>" width="<?php echo HEADER_IMAGE_WIDTH; ?>" height="<?php echo HEADER_IMAGE_HEIGHT; ?>" alt="" />

expand it to accomodate the function call:

<img src="<?php if (function_exists('rotate_default_headers')) rotate_default_headers(); else header_image(); ?>" width="<?php echo HEADER_IMAGE_WIDTH; ?>" height="<?php echo HEADER_IMAGE_HEIGHT; ?>" alt="" />

done – now you will have a different header image each time you switch to a new page (within the limitions of statistics, of course).