[self-interest] On "Meta," with a trick question at the end.

Albertina Lourenci lourenci at lsi.usp.br
Wed Jan 17 14:59:02 UTC 2001

David Ungar wrote:

> Well....if Randy is going to jump here, I could say that I agree with
> him. It is all about
> your purpose. For Self, we picked a set of things that were useful in
> regular programs and
> conceivably implementable, and encapsulation-respectiing, based on
> our idea of what
> object-oriented programming could be.
> Then there was a bunch of other stuff that needed to be there for the
> programming environment,
> that took an object's destiny away from it. That seemed like the meta
> stuff and went into the mirrors.

So the only concern of Self with metaprogramming sounds like this.
This makes reflection the same as metaprogramming right?
What about Self/R?  How will be reflection decisively made
explicit here?

It seems to me that the Self language happens! Indeed a happy
event! Similar to how Beethoven reacted to a lady who asked him
to explain his sonata. He simply played it again!

A smile,

> - Dave
> At 4:23 PM -0800 1/16/01, Randy Smith wrote:
> >Don't forget to look at the trick question at the end
> >of this note. Meanwhile....
> >
> >
> >>  > > what is meta-programming?  >
> >
> >Jecel gave 3 good examples, including a Self program.
> >
> >>  > This program is *about* a program -
> >
> >..and this to me is the key word:  "about."  A meta discussion
> >is about a discussion.  A meta program is about a program.  A
> >meta X is about an X.
> >
> >Now one must use some interpretive framework to decide what
> >something is about or even if it is about anything!  So the
> >question of the degree to which something is meta is one of
> >interpretation.  In other words, rational people may disagree
> >about the metaness of some object.
> >
> >For example, information about the representation of an object
> >is normally considered meta.  The number of slots, the names of
> >the slots and so forth.  Now consider:  is the size of a
> >collection a meta notion?  It does not depend on the
> >representation of the collection, and is at times something you
> >want to know when working with the thing.  Hence some might
> >consider a collection's size a rather everyday, non-meta
> >concept.  Others might say it is meta, as it is clearly about
> >the collection.  Obviously in Self we take the former view, and
> >let you directly ask the object for its size (in Self we use
> >mirrors for the meta stuff, like slot manipulations).
> >
> >So the choice of trying to put "meta" aspects into a special
> >world of mirrors is a choice to confront a mess of vague and
> >arguable decisions.  However, we figured it was a practical
> >factoring, even if it was an uncharacteristically non-Self-like
> >to introduce unneeded distinctions.
> >
> >Hey, how about the metaness of the following, which refers to
> >itself and is therefore meta?  "If this sentence is true, it is
> >not meta, otherwise it is meta."
> >
> >Is it an empty trick or does it reveal a problem with the
> >meta/nonmeta distinction?
> >
> >--Randy
> --
>      David Ungar
>      Sun Microsystems Laboratories
>      (650) 336-2618

| Albertina Lourenci                                       |
| PhD  in Architecture and Urbanism                        |
| post-doctorate researcher                                |
| Laboratory of Integrated Systems University of Sao Paulo |
| Avenida Professor Luciano Gualberto, 158 Travessa 3      |
| CEP: 05508-900                                           |
| Sao Paulo Sao Paulo State Brazil                         |
| Voice: +55 011 818 5254                                  |
| Fax: +55 11 211 4574                                     |

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