Re: meta-class subclass relationships

On Nov 16, 2007 6:47 PM,  <[e-mail]> wrote:
> On Sat, Nov 17, 2007 at 07:01:08AM +0900, _why wrote:
> > Maybe such things would be better suited with a super- but I like
> > both English and Ruby for the ways you have a bit of... errr...
> > poetic license, I guess.
>
> Meta is a prefix of Greek origin[1].  The Latin would be ``post'', which
> leads me to two thoughts.
>
> * A ruby metaclass really is like a postclass, which is pretty neat.
>
> * We're overusing prefixes like meta when so many options exist, such as
> postclass, or what about panclass, hypoclass, or epiclass[2]?  I know,
> there's eigenclass, but does that really clarify it for anyone?
>
> Metaclass is already embedded in the culture, but I nonetheless
> find this to be a useful way to reason about the concept and how it fits
> into the language.
>
>
> [1] http://en.wikipedia.org/wiki/Meta

Excerpting from that article:
=======
In epistemology, the prefix meta- is used to mean about (its own
category). For example, metadata are data about data (who has produced
them, when, what format the data are in and so on). Similarly,
metamemory in psychology means an individual's knowledge about whether
or not they would remember something if they concentrated on recalling
it. Furthermore, metaemotion in psychology means an individual's
emotion about his/her own basic emotion, or somebody else's basic
emotion

...

Etymology

The prefix is derived by back-formation from the Greek preposition and
prefix meta- (μετά) which meant either "after", "beside" or "with".
Meta- & Meso- are thought to have come into Greek together from a
mutual cognate, which would further imply 'meta' to contain or be of
the meaning "parallel". [1]

Quine and Hofstadter

The OED cites uses of the meta- prefix as "beyond, about" (such as
meta-economics and meta-philosophy) going back to 1917. However, these
formations are directly parallel to the original "metaphysics" and
"metaphysical", that is, as a prefix to general nouns (fields of
study) or adjectives. Going by the OED citations, it began to be used
with specific nouns in connection with mathematical logic sometime
before 1929. (In 1920 David Hilbert proposed a research project in
what was called "metamathematics.")

A notable early citation is Quine's 1937 use of the word
"metatheorem", where meta- clearly has the modern meaning of "an X
about X". (Note that earlier uses of "meta-economics" and even
"metaphysics" do not have this doubled conceptual structure, they are
about or beyond X but they do not themselves constitute an X). Note
also that this modern meaning allows for self-reference, since if
something is about the category to which it belongs, it can be about
itself; it is therefore no coincidence that we find Quine, a
mathemetician interested in self-reference, using it.

Douglas Hofstadter, in his 1979 book Gödel, Escher, Bach (and in the
sequel, Metamagical Themas), popularized this meaning of the term.
This book, which deals extensively with self-reference and touches on
Quine and his work, was influential in many computer-related
subcultures, and is probably largely responsible for the popularity of
the prefix, for its use as a solo term, and for the many recent
coinages which use it. Hofstadter uses the meta as a stand-alone word,
both as an adjective and as a directional preposition ("going meta", a
term he coins for the old rhetorical trick of taking a debate or
analysis to another level of abstraction, as in "This debate isn't
going anywhere."). This book is also probably responsible for the
direct association of "meta" with self-reference, as opposed to just
abstraction. The sentence "This sentence contains thirty six letters."
along with the sentence it is embedded in are examples of sentences
that reference themselves in this way.
====

This is the sense of meta in metaclass.  First it was adopted from the
greek meta. Although the Greek meta and Latin post might have some
meanings in common.  I've got a hard time understanding how postclass
would mean anything like metaclass.  and postmemory for metamemory,
postemotion for metaemotion and  postdata for metadata just don't ring
true.

The reference to Hoftstadter's GEB and it's publication date of 1979
is interesting.  I can't remember exactly when in the evolution of
Smalltalk the term metaclass was born, but it was definitely there in
the 1980 version.

It just so happens that I pulled my old copy of GEB down from the
attic a week or so ago.  Rereading it has been competing for my
reading time with "SQL for MySQL Developers." An interesting note is
that back then a 777 page textbook sold for $17.50 back then!

-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/