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   Re: [xml-dev] Semantics, Complex Systems, (XSLT) Programs which Write T

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On Wednesday, Oct 29, 2003, at 14:10 Europe/Berlin, Didier PH Martin 
wrote:

> Hi James,
>
> James said:
> the analogy is not accurate and "adaptive object models" are decades
> old.
>
> Didier replies:
> Can you explain your statement? Go you expand? Do you mean is decades 
> old in
> certain languages? Have you read the document at the site I referred? 
> Have
> you noticed that it is language independent?

the last time i looked at this work was several years ago. i was 
surprised that one thought it was significant then. yes the concepts of 
abstraction, delegation, composition, and prototypes are language 
independent. one can work directly with such concepts at various levels 
in languages which do go back decades.

the concepts do not change because one expresses them in uml and 
externalizes them in xml/xmi.

>  Is language independent
> "adaptive Object Models" decades old? Come on James...

languages which can represent such features - with and without 
resorting to the specific modeling methods which one must use a static 
language in order to avoid, as they phrased it "that the system would 
need to be recompiled and released to users of the system," are not 
new. ANSI Common Lisp, (American National Standard X3.226) was ratified 
in 1994. ok, i fudged. it formalized an industry practice which went 
back twenty years and incorporated concrete standards and 
implementation features which date from the early eighties. [0,1] 
smalltalk-80, as is evident from the name, existed in concrete terms 
well before clos. these are both languages in which it is not only 
possible, but indistinguishable from standard practice, to modify not 
only data and not only classes but also metaclasses over the life of a 
running system.

note please, the background of the researchers in this area and their 
own statements about the close match to smalltalk.


>
> On Tuesday, Oct 28, 2003, at 15:48 Europe/Berlin, Didier PH Martin
> wrote:
>
> James said:
> to take this example, in order to relieve the use of the "operator"
> task, the system would have to accept the assertion, that the even
> occurred, together with a description of its consequences, and proceed
> to rewrite the object metamodel and instance model itself. manual
> changes to the metamodel with automatic propagation to an instance
> model are old technology and are one level lower than the paradigm's
> aspirations.
>
> Didier replies:
> Can you explain how you would do that in C++ or Java? I am listening.

i would not try to do it in c++ or java. i would use clos or smalltalk. 
directly.
yes, they propose patterns and structures which make it possible to 
accomplish some of the same things in static languages like c++ and 
java. the only thing which i had found useful in their papers was the 
effort to standardize rule-based typing. i didn't thin it was worth the 
baggage.

>
> James said:
> that's also still one level down.
>
> Didier replies:
> Can you explain?

the user still has to be familiar with specific concepts and re-express 
their observations and/or requirements in those terms. they say it's 
not "programming" because it is not java and does not need to be 
"compiled". i suggest that the distinction is not material.


[0] 
http://www.csee.umbc.edu/331/resources/papers/Brief-History-of-Lisp.pdf
[1] http://www.dreamsongs.com/NewFiles/HOPL2-Uncut.pdf





 

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