[cad-linux] Re: data format vs data system

Eric Wilhelm said:     (by the date of Thu, 18 Sep 2003 23:40:16 -0500)

> I think it is great to start simple, but we should also try to envision the 
> future uses and requirements, which will allow the design to evolve without 
> huge setbacks.

exactly

> One of the issues that comes up immediately is how to expand this 
> format/system to parametric data.

we've been talking about 'addtef' attributes in thread Re: block attributes
http://www.freelists.org/archives/cad-linux/09-2003/msg00190.html

and yet we will have to find some kind of solution. I think that each
directory could have a file with those attributes listed. It will be
treated just like declaring variables that have the scope of the current
directory. Any other files in this directory can refer to this attribute
and treat it as a value (everything is passed as text, numbers also)

Calling this directory from somewhere else (like inserting a block) will
have the ablility to define the values of those variables. If not
defined - then use default value. If default value is missing - then
print warning on stderr, and use nothing (empty value).

interesting thing - if an empty value is used as an X coordinate of a
point, then this point exists, but it has 'wrong' coordinates and cannot
be plotted. (Not a Number is different that zero ;) 

> Maybe a more important question, which would likely provide the answers to a 
> lot of these details, is what would be the central defining metaphor for the 
> format?  (example:  with Unix, "everything is a file" has been central to the 
> design of all things Unix)
> 
> Maybe we should come up with a label other than "format"?   
> 
> Database Specification?
> 
> daSpec?

heh. you are talking about a name for our new baby :)

personnally I'm going to agree on almost anything ;) I started to use a term:
Cad Directory Data Format = CDDF
and (just to have some relax a few days ago) I drew with gimp this:
http://absurd.kozicki.pl:8435/~www/Cad-Linux/cdf.png

don't laugh ;-)) ;-))

if you prefer daSpec then we should ask other people what they do think
about this?

-- 
# Janek Kozicki

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