Hacker News new | ask | show | jobs
by jiggy2011 5104 days ago
This is the best approach , but it is best combined with fairly comprehensive re factoring otherwise you end up in a situation I have been in a few times where you have new code that runs with a nice abstraction and old code that works with less abstraction.

At that point you can introduce bugs because somebody modifies the old code in a way which would not be allowed under the new abstraction and then the new code ends up reading data produced by the old code leading to a cascade of failure.