Re: datatypes in Elisp Info: mention "things" for which there is no "thing" datatype - e.g. faces

[Thien-Thi Nguyen <ttn@gnu.org>]

"Drew Adams" <drew.adams@oracle.com> writes:

> Finally, I'm ignorant: Just why is `face' not treated similarly to
> `function' - why isn't `face' a datatype? If the answer expresses a
> general rule, then perhaps that rule should also be included in the
> doc, to clarify things.

probably the general rule is not to introduce too many fundamental
types, as doing so exponentiates complexity, unless absolutely
necessary.  for faces, it doesn't appear to be necessary.

i got on a kick of documenting internals (to exercise a pet doc
extraction system i wrote) for a personal project and am now wondering
how it was that enthusiasm triumphed over experience Yet Again...  so,
while i agree that the documentation could make more distinction between
fundamental and composed (or "defined-by-conventional-use") types, i
figure that doing so might be a bad idea because it would constrain the
implementation.

since `facep' works like `functionp' (fsvo "like"), that should be what
programmers rely on.  if in the future faces become fundamental, that
transition will be easier to handle if prior internals were left
unexposed (ignorance is bliss).

thi