On Wednesday, 22 April 2015 at 19:29:08 UTC, Walter Bright wrote:
I'd missed this post on reddit:
http://www.reddit.com/r/programming/comments/30wj8g/managing_cs_complexity_or_learning_to_enjoy_c/cpx41ix
Thanks for the mention. I must have forgotten some. I should put
in in a d-idioms anyway.
I didn't appreciate how important default initialization was
before having to fix a non-deterministic, release-only,
time-dependent bug in a video encoder some months ago. Just
because of 2 uninitialized variables (C++ doesn't require member
initialization in constructor). If one of them was _exactly equal
to 1_ by virtue of randomness, then it would perform from 0 to 2
billions of motion estimation steps, which is very slow but not a
total halt. A watchdog mechanism would detect this and reboot,
hence labelling the bug "a deadlock". It would disappear in debug
mode since variables would be initialized then.
That gives a totally other meaning to "zero cost abstractions"
since in three weeks of investigation I could have speed-up the
program by ~5%, much more than the supposed slowdown of variable
initialization.
