Mail Archives: geda-user/2015/08/03/07:50:38
On Aug 3, 2015, at 6:42 AM, Gabriel Paubert (paubert AT iram DOT es) [via geda-user AT delorie DOT com] <geda-user AT delorie DOT com> wrote:
> On Sun, Aug 02, 2015 at 07:22:56PM -0400, John Doty wrote:
>>
>> On Aug 2, 2015, at 5:22 PM, Gabriel Paubert (paubert AT iram DOT es) [via geda-user AT delorie DOT com] <geda-user AT delorie DOT com> wrote:
>>
>>> I always had the impression that the attribute handling rules are too
>>> complex;
>>
>> Yes, although part of the problem is just confusing terminology. We could use the terms “override default” and “restore default” for promoting and deleting instance attributes. That would make the existing functionality clearer, I think.
>>
>>> it would be much simpler to say that all attributes are promoted
>>
>> Ah, but that causes chaos for those of us who sometimes use “heavy” symbols.
>
> At least for my workflow (I use gschem almost exclusively to design pcb),
> I have come to the conlusion that heavy symbols are a pain. I started from
> moderately heavy symbols and tend to go towards lighter and lighter symbols.
It depends a lot on what you’re doing. Sometimes light is better, sometimes heavy is better. Hurray for flexible tools!
An example of a use for heavy symbols is a project-wide default for passive component packaging. I’ll typically put resistor and capacitor symbols in the project symbol directory. The footprint will be whatever I want for the project default: 0805 to minimize strain on my sexagenarian eyes, 0603 if there’s a limit to the board size, or 0402 if I really have to squeeze. Of course, some values/specs won’t be available in the default package so I’ll promote the footprint and make it what it needs to be in those cases. Then, if I change the default, the footprints that shouldn’t change don’t change.
>
>> You often want to be able to edit the symbol once to change attributes for all of its instances.
>
> Couln't it be solved by better tools?
DJ’s “database” layer between schematics and layout might be nice, but it should, of course, be an option, not forced on flows that don’t need it. In the mean time, what we have is pretty useful and flexible. That’s the difference between the geda-gaf philosophy and the pcb philosophy. Pcb *needs* a specific tool/feature to do anything. Geda-gaf gives you a few capabilities and gets out of your way, letting you use them however you need.
John Doty Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd AT noqsi DOT com
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