Lessons from the refactoring trenches

Lessons so far from the refactoring trenches

1: Forgetting a break; in a C switch statement really hurts.
   Usually by random strange errors somewhere completely unrelated because
   something got reset to a second value, free()d, allocated as the wrong
   thing, etc.

2: A lot of the perl header macros don't evaluate their arguments more than
   once, and a lot of the perl core code relies on this, using things such
   as *sp++ inside macros.

Nicholas Clark