The Magic of Curses 115Senseless Separators
The myopia surrounding terminal handling has an historical basis. It begins
with the idea that the way to view a text file is to send its characters to the
screen. (Such an attitude is commensurate with the “everything is a stream
of bytes” Unix mantra.) But herein lies the rub, for doing so is an abstrac-
tion violation. The logical structure of a text file is a collection of lines sep-
arated by some line separator token. A program that understands this
structure should be responsible for displaying the file. One can dispense
with this display program by arranging the line separator to be characters
that, when sent to the terminal, cause it perform a carriage return and a line
feed. The road to Hell is paved with good intentions and with simple hacks
such as this. Momentary convenience takes precedence over robustness
and abstractness.
Abstraction (an API) is important because it enables further extension of
the system; it is a clean base upon which to build. The newline as newline-
plus-carriage-return is an example of how to prevent logical extension of
the system. For example, those in the Unix community most afflicted with
microcephaly are enamored with the hack of generating files containing
escape sequences that, when piped to the terminal cause some form of ani-
mation to appear. They gleefully mail these off to their friends instead of
doing their homework. It’s a cute hack, but these files work only on one
kind of terminal. Now imagine a world with an API for directing the termi-
nal and the ability to embed these commands in files. Now those files can
be used on any terminal. More importantly, this API forms a basis for
expansion, for portable files, for a cottage industry. For example, add
sound to the API, and the system can now boast being “multi-media.”
Fundamentally, not only is an API needed, but it must either be in the ker-
nel or be a standard dynamically linked library. Some part of the OS should
track the terminal type and provide the necessary abstraction barrier. Some
Unix zealots refuse to believe or understand this. They think that each pro-
gram should send its own escape sequences to the terminal without requir-
ing the overhead of an API. We have a proposal for these people. Let’s
give them a system in which the disk is treated the same way the terminal
is: without an API. Application programs get to send raw control com-
mands to the disk. This way, when a program screws up, instead of the
screen containing gibberish, the disks will contain gibberish. Also, pro-
grams will be dependent on the particular disks installed on the system,
working with some but not with others.
Of course, such a proposal for controlling a hard disk is insanity. Every
disk drive has its own characteristics: these differences are best handled in