Ghosts of Unix past, part 3: Unfixable designs

“In the second installment of this series, we documented two
designs that were found to be imperfect and have largely (though
not completely) been fixed through ongoing development. Though
there was some evidence that the result was not as elegant as we
might have achieved had the original mistakes not been made, it
appears that the current design is at least adequate and on a path
towards being good.

“However, there are some designs mistakes that are not so easily
corrected. Sometimes a design is of such a character that fixing it
is never going to produce something usable. In such cases it can be
argued that the best way forward is to stop using the old design
and to create something completely different that meets the same
need. In this episode we will explore two designs in Unix which
have seen multiple attempts at fixes but for which it isn’t clear
that the result is even heading towards “good”. In one case a
significant change in approach has produced a design which is both
simpler and more functional than the original. In the other case,
we are still waiting for a suitable replacement to emerge. After
exploring these two “unfixable designs” we will try to address the
question of how to distinguish an unfixable design from a poor
design which can, as we saw last time, be fixed.”

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