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Re: gEDA-user: gnetlist

On May 31, 2011, at 6:35 AM, John Griessen wrote:

> I'd like the first definition
> of what gnetlist does be, "Output any data it takes in, in the same format,
> with lost spatial position information allowed, but keeping all other data intact."

I think the reader should preserve *all* of the information in a .sch file. There are several reasons:

1. Net connectivity depends on spatial information. But one approach doesn't fit all needs here. Right now, we have a simple minded netlister that reduces the net geometry in the schematic to a netlist model in which a net is topologically a single point. But suppose we start putting attributes on net segments ("this segment must carry 10A")? Shouldn't a back end for a layout tool that can handle this be able to see this, figure it out?

2. Some would like busses to be more than decoration. A plug-in to do this wouldn't be hard, if bus and net geometry was accessible.

3. Netlisting isn't everything. A major application of a reader/writer library will be scripts for annotating schematics, I think.

It seems to me that the .sch file format is well suited to representation as S-expressions. A list of objects, each potentially attached to a list of objects, ...

John Doty              Noqsi Aerospace, Ltd.

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