I've seen dozens of those "personal failures." :-) Granted, backwards ABI compatibility is a huge, complicated, thankless task for which you get no notice if

I've seen dozens of those "personal failures." :-) Granted, backwards ABI compatibility is a huge, complicated, thankless task for which you get no notice if you do the job perfectly. The ideal spot for the "break old programs" vs. "cripple new programs to avoid breaking old ones" dial is different for every project. Sometimes the right thing to do is keep the code base from degenerating into a pile of back-hacks. Sometimes it's all about bending over backwards to keep a long-gone vendor's bug from biting your end users.