@electricfeet: this is the beauty of WP and its’ child themes system.
functions.php of the child theme is an addition to functions.php of the parent theme.
The really cool part is that the child version is read just before the parent version. Why is it so cool? Because it gives theme developers the ability to make their functions pluggable. To wrap them in a
if( ! function_exists('name_of_function') ) {
function name_of_function( $params ) {
// do some stuff with the $params }
}
This gives child theme ‘devs’ the ability to completely replace functions declared in the parent theme. By the time WP finds them in parent functions.php they exist and get skipped (because of the function_exists() condition).
However, nikeo used another great feature of WP: apply_filters().
This gives us the ability to declare (in functions.php of the child theme) a new function that filters the output of an existing one (so we’re not replacing the function, just alter/replace its output):
add_filter('old_function', 'new_function');
Now all you need to do is create the new_function() (also in your child theme’s functions.php). Without any parameter, it simply replaces the output of old_function with its own output:
function new_function() {
$new_output = 'New output';
echo $new_output;
}
If you want the new_function to alter the content of old_function, declare it with one parameter, and that param will contain the output of the old_function:
function new_function($output) {
/* $output now holds the output of the old_function and you can alter
* it as you want, using preg_replace or adding to it or hacking it
* anyway you like. In this example I'm just adding $new_output after
* the original output:
*/
$new_output = '<div>This text has been added using apply_filters on old_function(), never touching parent theme core files! Cool, huh?</div>';
echo $output.$new_output;
/* Please note that some functions need the output echoed and others
* want it returned, so you'll need to replace echo with return in
* some cases. Just look at old_function() and you'll know.
*/
}
Hope this sheds some light on why WP’s slogan is “Code is poetry”. ??
And why nikeo did such a great job with the dev tools. If you look in the tootips, you will see on last line:
filterable with: add_filter(‘name_of_original_function’, ‘generic_name_for_new_function’); so you can add in your child theme’s functions.php
add_filter('name_of_original_function', 'coolest_function_name_evah')
function coolest_function_name_evah($original_output) {
// filter and return/echo the output to your liking
}
And you’re done without having to worry about Customizr updates overriding your filter.
