What is the WordPress `WP_Hook` class architecture and how did it replace the previous array-based hook implementation?

Question

WordPress Expert — Hard

What is the WordPress `WP_Hook` class architecture and how did it replace the previous array-based hook implementation?

Accepted Answer

The WordPress `WP_Hook` class architecture replaced global $wp_filter arrays with an OOP class that handles priority-sorted callbacks and recursion detection during filter execution. This solved issues like infinite recursion or missed removals when removing a hook from within its own callback.