Re: gEDA-user: General Layers questions

[Stephan Boettcher <boettcher@xxxxxxxxxxxxxxxxxx>]

DJ Delorie <dj@xxxxxxxxxxx> writes:

>> ... I think the tool we have is pretty good already. Very good.  Thanks!
>
> The tool we have already is nearly impossible to maintain, though.
>
>> Please do not expect that users write plugins.  The tool is already too
>> good as it is to make is worth the effort to learn how to do that.
>
> I expect the plugin mechanism to be the way to write *all* the core
> bits, though. 

The more important it is, that what is below the plugin mechanism is as
general as necessary, and since that is difficult to judge up front: as
general as possible, without compromising the final goals.

I'd propose a very basic, very general storage data representation.
Just layers, shapes, and arbitray levels of composites, the layout
implicitly being the top level composit. Everything with arbitrary
attributes.

On top of that is a memory representation, that introduces the concepts
of elements, vias, surface-layers (layer sets: copper, mask, silk,
courtyard, keepout), connectivity, ....  

It provides basic operations on these concepts.  The implementation of
these concepts builds on the objects of the storage data layers.  It
must not be an error if a via has two holes, a polygon shaped hole or
silk in it.  DRC may flag such things, but it must not be an error.
The attributes that this memory representation and it methods understand
shall be in namespace "pcb:" and unknown attributes in that namespace
shall emit warnings.

The plugins define their own attributes.  Attributes shall not be
overloaded.  If a plugin operates on attributes of the memory
representation, it shall do that via methods of that representation, if
possible.  

Higher level parts of the concepts "element", "via", "surface layer"
may be implemented in plugins.




I cannot keep up, there are 15 new messages in my inbox, lets see what
what new arguments come up :-)

I cannot make up my mind if I should continue to argue for hole layers,
or if holes shall be shapes with hole attribute on layers.

> The fact that the *user* can write them *also* is a side-effect :-)
>
>
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-- 
Stephan BÃttcher                     FAX: +49-431-85660
Extraterrestrische Physik            Tel: +49-431-880-2508
I.f.Exp.u.Angew.Physik               mailto:boettcher@xxxxxxxxxxxxxxxxxx
Leibnizstr. 11, 24118 Kiel, Germany


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