Re: gEDA-user: Bug report for renaming slots [Was: Re: gEDA on windows]

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Mon, 2009-01-12 at 18:53 -0800, Joerg wrote:
> Peter Clifton wrote:

> > Actually, your idea has got me thinking more about how we handle
> > attributes on slotted parts, and the possibility that they could in some
> > way be treated as an aggregate component for the purposes of attributes
> > other than "slot=".
> > 
> 
> Not 100% sure if I understand correctly but yes, treating all slots as 
> one component would be feasible. Even if you don't use all you must 
> usually place all slots anyhow and, for example, connect inputs to GND. 
> Exception being transistor arrays but even they should also be grounded 
> and be on the schematic so folks can see what's available for cut/jumper 
> style rework purposes.

Sorry for typing before thinking that through fully. Treating all slots
as one component (for adding attributes) isn't actually possible with
gEDA's architecture. Attributes can only be added to symbols.

I can imagine the GUI glossing over that fact, and perhaps offering to
help keep attributes in sync when renaming a single slot, it would be
difficult (perhaps impossible) to cater for the case where you have some
slots on one schematic page, and others elsewhere.

> That would be a serious one. I can't recall a single company I dealt 
> with not using A, B, and so on (upper case). Most CAD programs 
> auto-assign those when you place until you run out of slots. So if you 
> place eight slots of a six-slot 74HC14 it bumps the refdes number for 
> the last two you place. They don't all do it perfectly. OrCad usually 
> does but I've had Eagle "forget" when I began placing some more slots 
> later. gschem just places all as first slots with U? right now.

Tricky to figure out how to do this flexibly. gEDA's flexibility means
special casing behaviours like this is hard (and often undesired). Some
kind of script or plugin hook might be a possible way to do this, but
again.. I'm just thinking "aloud".

(I'm not suggesting users would have to write these scripts, more that
they shouldn't form part of gschem's hard-coded behaviour.)

As an example I wrote for someone (and I ended up using it myself), I
have a script hook here which renames any component I copy back to
"U?" (removes the numbering), so that I don't end up accidentally naming
two components the same due to a copy-paste in my schematics.


Joerg: I think I have some understanding now of the kind of visual
appearance of schematics you're thinking of, but I'm curious to see (if
you have any examples you could share - perhaps by private email), just
what the kind of schematic you're talking about looks like. (Either
slotted logic gates, or slotted op-amps).

I'd like to put the discussion in context by seeing how a real schematic
looks using the styles we discussed, rather than just my mental pictures
so far, which just cover a symbol and its visible pins.

-- 
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!)



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