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

[Stephan Boettcher <boettcher@xxxxxxxxxxxxxxxxxx>]

Peter Clifton <pcjc2@xxxxxxxxx> writes:

> On Wed, 2009-11-18 at 09:23 +0100, Stephan Boettcher wrote:
>> Peter Clifton <pcjc2@xxxxxxxxx> writes:
>> 
>> > On Tue, 2009-11-17 at 17:10 -0500, DJ Delorie wrote:
>> >> 
>> >> What you want is a four-slot-slotted gate symbol, and a separate power
>> >> symbol.  The slots permute across {gate 1, gate2} x {A-B inputs, B-A
>> >> inputs}.  I.e. you can use the slotting to switch gates *or* swap the
>> >> pins.  It's worth the effort to get this working smoothly.
>> >
>> > ARGH!! Sounds like a real misuse of the slotting feature to me. It makes
>> > any potential DRC checks for "did the user use all the slots" near
>> > impossible to implement as well.
>> 
>> To me this sounds like a very good use of a flexible sloting mechanism.
>> With some extra attributes to steer the DRC this should be all fine and
>> transparent.
>
> It is a perfect example of why gEDA can never grow more "friendly"
> interfaces to these problems. _Because_ the existing interface can be
> abused - and people think it is a good idea to encourage such
> "flexibility", we end up with designs out there relying on the
> behaviour.

I'd not call that abuse.  The current sloting mechanism allows to change
pin numpers on a drawn component to switch to a different instance of the
component inside the same package.

We also call for changing pin numbers when we replace one package type
with another.  What is so bad proposing to generalize the existing
mechanism to cover both cases cleanly, instead of implementing another
mechanisem that does almost the same?

> The exponential increase of special-cases / "what if the user abused the
> feature by doing .....", stops us from wrapping any of these features in
> nicer interfaces. It prevents decent attribute validation / design rule
> checks, and any hope of wrapping a GUI around the problem (should that
> be desired).

The GUI may implement user-frienly policies how to use very flexible
mechanism in a newby-firenly way, without restricting how other UIs uses
the same mechanisms for other purposes, and without calling those other
uses "abuse".

> If you propose adding extra attributes to steer the DRC system around
> the hack, you might as well propose an expressive attribute based scheme
> for pin / gate swapping instead.

I think I'd prefer flexible mechanism instead of multiple mechanism
doing almost the same.

Stephan


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