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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

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,

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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