<somecodingsystem> (was: Re: Replacement for string-as-unibyte-function)

[moasenwood--- via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

Stefan Monnier wrote:

> Emacs receives the data from the process as a sequence of
> *bytes* (after all, that's the only thing available in POSIX
> communication). So in order to pass a sequence of *chars*
> (aka "a multibyte string") to the process filter, Emacs's
> internal C code has to do the equivalent of
>
>     (*de*code-coding-string "thedatareceived" '<somecodingsystem>)
>
> where <somecodingsystem> is the coding system that
> `make-network-process` decided to use for that process.

Interesting, are we here talking computer communication in the
protocol sense, which is basically the format of the message
(the syntax of the packet, usually it has field with different
metadata, then payload (the actual message), and BTW the
metadata can refer to both the payload (e.g., its length) but
also to the communication itself), furthermore the protocol
stipulates the way messages should be sent between hosts
(e.g., in what order), and last but not least, when syntax and
procedure is covered, what it all means - the semantics.

This is illustrated with Alice and Bob in the Anglo-American
world and Abelard and Héloïse in the Franco-phone world, with
arrows going back and forth between them. (Apparently they
existed, and exchanged letters in the 12th century [1].) (I
use to joke about "Care of Héloïse" when I clean and organize
all my zillion tools and toolboxes. Get it? Instead of "Care
of Kit" :) [2])

This is what I remember from school anyway. Or is it more like
Unix IPC? In that case, what I remember ... err, we all use
IPC every day.

What I _don't_ have a snappy answer for, not from school and
not from everyday life, is <somecodingsystem>? What is
a coding system?

[1] https://en.wikipedia.org/wiki/H%C3%A9lo%C3%AFse

[2] https://dataswamp.org/~incal/tree-house/care-of-heloise.jpg [photo]

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