get_parent_theme_file_path vs. get_template_directory

Question

I've been reading about the new functions for referencing theme location added in v4.7.

I read through the trac ticket. I understand why they created these functions and the benefit of get_theme_file_path() for use in child themes. But aside from verbal clarity is there a specific reason to use get_parent_theme_file_path() over get_template_directory() when referencing files in the parent theme?

Answer 1

Is there a specific reason to use get_parent_theme_file_path() over get_template_directory()

Yes. This new function comes with a filter

• Filter parent_theme_file_path
• And argument to the file path

If you take a look at the get_parent_theme_file_path() source, it's just returning get_template_directory() with extra functionality like if a file is given as an argument to the get_parent_theme_file_path it returns path to the file and it also comes parent_theme_file_path filter which is very good to override.

get_parent_theme_file_path is introduced for consistency and to allow child themes to override easily. I don't see any point not to use this instead of get_template_directory.

I wrote a post on these functions, that can be helpful.

Use case:

Suppose you are including a file in the theme using get_template_directory like the following.

include(get_template_directory().'/inc/bk.php'); /*../themes/bk-theme/inc/bk.php */

and if you want to override bk.php in the child theme it's not possible

If you include the same file with the new function

include(get_parent_theme_file_path('inc/bk.php')); /*../bk-theme/inc/bk.php */

You can easily override this file inclusion in the child theme using parent_theme_file_path like the following

add_filter('parent_theme_file_path','bk_257597_parent_theme_file',10,2);
function bk_257597_parent_theme_file($path,$file){
 if('inc/bk.php' == $file) {
  //do something
  $file = 'my-file';
  $path = 'my-path'.$file;
 }
 return $path;
}