[TUHS] Comments in early Unix systems

Doug McIlroy doug at cs.dartmouth.edu
Thu Mar 22 23:49:02 AEST 2018

"I was told in school (in 1985) that if I was ever lucky enough to
have access to the unix source, I'd find there were no comments. The
reason, I was told at the time, was that comments would make the
source code useful, and selling software was something AT&T couldn't
do due to some consent decree."

I can't speak for SYS V, but no such idea was ever mentioned in
Research circles. Aside from copyright notices, the licensing folks
took no interest in comments. Within rsearch there was tacit
recognition of good coding style--Ken's cut-to-the-bone code was
universally admired. This cultural understanding did not extend
to comments. There was disparagement for the bad, but not honor
for the good. Whatever comments you find in the code were put
there at the author's whim.

My own commenting style is consistent within a project, but
wildly inconsistent across projects, and not well correlated
with my perception of the audience I might be writing for.
Why? I'm still groping for the answer.

For imoortant code, custom is to describe it in a separate
paper, which is of course not maintained in parallel with
the code. In fact, comments are often out of date, too.
Knuth offered the remedy of "literate programming", which
might help in academic circles. In business, probably not.
Yet think of the possibility of a "literate spec", where
the code grows organically with the understanding of what
has to be done.


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