Subject:           Phase of the moon


We always liked to talk about the bugs that depended on the phase of the
moon. So, when Guy Steele wrote the Rabbit compiler, which is a scheme
compiler, he made it print out a comment at the beginning which showed
the time it was could always look. If you had a bug that depended on the
phase of the moon, you could look at the thing and see at what phase of
the moon it was compiled, and that might help you figure out what went
wrong.

Eventually, he got a bug report about a certain program that had
been compiled once, and worked, and when it was compiled at another time
it didn't work. So, he looked and he discovered that when the initial
comments were printed out, the LISP feature that would automatically
put in a line break if a line got too long was activated on one occasion,
because the phase of the moon took too many characters to print out. So,
it triggered that feature, and the last part of the phase of the moon was
on another line, and therefore it wasn't marked by comments. So it was
just sitting t here in a file, whereas at another time the phase of the
moon didn't take up so many characters, and the whole thing was properly
commented. So, this was a bug that actually depended on the phase of the
moon. You can take that as a final thought.