Overriding a plugin's pluggable function in theme's function

Question

I came across this snippet - https://gist.github.com/mikejolley/1751128 - that creates a function with the same name as an existing WC function as a means of overriding it.

I also learnt that this way of overriding works because the original function is 'pluggable' due to the !function_exists() function.

My question is since plugins gets loaded before themes i.e., WC would have created the function first, shouldn't the attempt to override the function fail because the 'if (!function_exists('woocommerce_template_loop_add_to_cart'))' condition isn't satisfied?

Appreciate any input!

Answer 1

The WooCommerce file that defines its pluggable functions isn't loaded until after themes are loaded. It does this by hooking a function that includes the file into the after_setup_theme hook:

add_action( 'after_setup_theme', array( $this, 'include_template_functions' ), 11 );

That's from the /includes/class-woocommerce.php file in WooCommerce. The include_template_functions() function includes the file that defines functions like woocommerce_template_loop_add_to_cart().