Re: gEDA-user: How to deal with single/dual parts?

[John Doty <jpd@xxxxxxxxx>]

On Nov 17, 2009, at 3:17 PM, Dave N6NZ wrote:

> I'm curious as to why you found slotting problematic?  It's no more or
> less obtuse than the rest of gschem.

It's much more troublesome. Every attribute that is given special  
treatment by libgeda or the gnetlist front end is associated with a  
rigidity that will cause problems for some flow.

One problem is that slotting doesn't play well with SPICE netlisting.  
Stuart's attempt to fix this a couple of years ago broke slotting in  
other ways, and was pretty confusing in its own right. Nobody's come  
up with a good solution.

Another problem is that it doesn't play well with hierarchy. Suppose  
you need a bunch of the same circuit, but one of the building blocks  
comes in pairs, and another comes in duals. That forces you to draw  
six of the circuit per block. And then maybe you need nine of them.  
At that point, hierarchy isn't worth it. But nine identical (from a  
signal flow point of view) circuits *should* be the kind of thing you  
do with hierarchy.

Construction of slotted symbols is a confusing process, as Stefan and  
Kai-Martin point out.

I agree with Peter that DJ's slotting tricks are an invitation to  
more chaos and confusion.

I'm thinking about a preprocessor for gnetlist that would do  
hierarchy expansion, parts selection, slot selection and automatic  
power block insertion, under control of a user-specified BOM and rule  
set. This would generate an expanded set of concrete "flat" project- 
oriented schematics from more abstract set of reusable input  
schematics. But it's a lot of work and I'm very busy right now...

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




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