How to cope code changes with WP updates

I document my hacks in a simple text file noting the files I’ve hacked. Then each time I do a hack in the core code, I comment it by entering my name…something like <!– changed by figaro –>

Then each time I upgrade, I use winmerge to compare the new code with my existing code and incorporate my hacks into the new code.

Not sure if that fits with your definition of efficient or not, but it works well for me.

Another possibility…years ago, I used the my-hacks.php file for my hacks. I See there is still a setting in Settings/Misc to use the my-hacks.php file, but I haven’t used it in years…not sure how well this still works, but here is some very old documentation on it.

http://ww.wp.xz.cn/development/2003/12/new-feature-my-hacksphp/