[cad-linux-dev] Re: YAML file format - Optional attributes
- From: Bruno Postle <bruno@xxxxxxxxxx>
- To: CAD linux development <cad-linux-dev@xxxxxxxxxxxxx>
- Date: Wed, 22 Sep 2004 14:01:36 +0100
On Tue 21-Sep-2004 at 18:48 -0500, Eric Wilhelm wrote:
> Two line entities of different versions within the same directory is
> incompatible with this. Similar sentiments for units, copyright,
> license, etc. That's why I think these things should only be defined
> in "./drawing".
The advantage of storing "copyright" at the entity level is that it
allows shared ownership of drawings.
For me the prime motivation for doing this stuff is that I see
systems that work wonderfully for software development which are
tragically unused in the design world - One of those systems is the
whole Open Source thing.
> This is what I've been calling the "grep litmus test".
> e.g., the following should tell me what layer ID's in this drawing
> contain lines:
>
> for line in `grep -l "^type: line" *.yml`
> do grep "^layer:" $line | sed 's/layer: \+//'
> done
A few comments:
* The YAML file format fails the grep test immediately as soon as
it moves beyond simple key/value pairs. For instance, how do you
ask the current system to list all circles with centres above the
value y=3?
To be able to do this with a grep-able format, all lists need to
be collapsed onto one line:
centre: 100, 5.6, 10
* Your shell script could easily output a default value if it can't
find a defined layer:
do (grep "^layer:" $line || echo '') | sed 's/^layer: \+//'
..or just use a YAML parser and don't worry about grep:
perl -MYAML -e "\$a=YAML::LoadFile(\"$line\"); print \"\$a->{layer}\n\""
* With AutoCAD, the "special" layer 0 is equivalent to an
unspecified layer, so this is exactly how existing CAD systems
work anyway.
--
Bruno
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