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Re: gEDA-user: Visual cue of zero length pin endpoint



On Sun, 2011-01-23 at 23:52 +0900, Andrzej wrote:
> Krzysztof,
> 
> > I'd like to get opinions on the drawing of visual cues (endpoints) of
> > pins. Curently:
> 
> This may not be a suggestion you expected, but... how about making the
> parser stricter and actually remove such shapes (and any other
> zero-sized objects) before they make their way into libgeda? These
> shapes violate the gEDA file format spec so if the tool is being
> sloppy about checking their properties, we will end up with 2 specs -
> one "official" and one "de facto" (particularly important for authors
> of third-party tools, as they will have to reproduce all the
> workarounds in libgeda).

libgeda was recently patched to allow zero length pins. Please point me
at where the documentation says this is invalid, and I'll file a bug
about getting that changed.

> Visual artifacts in rendered symbols are not the only problem. There
> might also be other functions that depend on directionality of pins. I
> vaguely recall that the pin direction is used by gschem for assisted
> routing of nets in schematics (as a preferred direction of a net
> connected to the pin).

You are correct there, those driving the zero-length pins change should
consider whether this is a problem or not, and if so - what do do about
it!

On cursory inspection, adding preferred net orientation could require a
file-format bump to do flexibly. A heuristic could be imagined, but it
won't be as easy to get right as it first sounds.


-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)
Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me)

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