I figured how how to override an arbitrary file in a child theme. It is ALMOST as simple as placing the override file in the corresponding folder for the child theme. The step I didn’t know about, was to add a require_once() for the specific file in the child theme’s functions.php. Here is my example step by step:
My example is how to replace the font list in Customizr theme, with my own font list.
1) If I were to “hack” the parent theme to make this change, I’d change the file wp-content/themes/customizr/core/init-base.php
2) Make a copy of core/init-base.php, make your changes, and place it in the child theme’s folder: wp-content/themes/customizr-child/core/init-base.php. Note you must create a “core” folder in which to place init-base.php — you must replicate the full path of the overridden file (or whatever file you refer to in step 3).
3) Modify your child theme’s functions.php to include the overriding file, by adding the following line:
require_once( get_stylesheet_directory() . 'core/init-base.php' );
Why? According to the WordPress codex: https://codex.wordpress.org/Child_Themes, about half way down, see …
Referencing / Including Files in Your Child Theme
When you need to include files that reside within your child theme’s directory structure, you will use get_stylesheet_directory(). Because the parent template’s style.css is replaced by your child theme’s style.css, and your style.css resides in the root of your child theme’s subdirectory, get_stylesheet_directory() points to your child theme’s directory (not the parent theme’s directory).
Here’s an example, using require_once, that shows how you can use get_stylesheet_directory when referencing a file stored within your child theme’s directory structure.
require_once( get_stylesheet_directory() . '/my_included_file.php' );
In my case, I’ll add this line to my child theme’s functions.php:
require_once( get_stylesheet_directory() . 'core/init-base.php' );
4) Upload the new file and the modified functions.php to your web server, and the next time you access the font choices in the customizr, you’ll see your new font list.
