On Sep 28, 2008, at 9:54 PM, Peter Clifton wrote:

> I'm of the opinion that the .sch file should still end up  
> containing all
> the required design information,

I have the opposite opinion. The "everything in the schematic"  
approach is a serious barrier to schematic reuse. It makes the  
process of choosing and and especially changing parts tedious and  
inefficient.

> even if we use a helper app. to fill in
> some of the blanks.
>
> The only exception to this feeling would be if the schematic stored  
> some
> attributes suitable for keying into a database which are picked up  
> by a
> gnetlist "back/front" end.

We have this capability already. Symbol files are nice flexible  
containers for the database information, easy to edit graphically or  
textually.

> This said, it would still be nice to see the
> schematic cache the results of any database lookup, so they can be
> distributed eaily to other parties who might not have the same  
> database
> setup.

The way I do this is that the design is a collection of files: there  
are often multiple top level schematics, and I use hierarchy quite a  
bit. Each project has a collection of project symbols that mostly  
start as copies of symbols from either the gEDA distribution or from  
a previous project.

Ideally, every component symbol should be in the project collection.  
Then "Hs" does exactly what you need: it edits the component database  
for your project.

The missing ingredient here is a simple one: the symbol browser  
should be able to automatically copy symbol files into the project's  
symbol repository. Right now, I find myself browsing for a symbol,  
getting its name, using "locate" and "cp" to get it to the project  
repository under a project-specific name, refreshing the symbol  
browser, and then browsing for and placing the symbol. This slightly  
inconvenient procedure saves a great deal of work later.

One thing that can get in the way is gschem's default of promoting  
attributes like footprint. That gets in the way: the project's  
default footprint isn't usually a sensible schematic-level attribute.  
Of course, if I have a special requirement for a particular instance,  
it's easy to override it with an attached attribute. So

What gEDA has now is tremendous flexibility. It makes more sense to  
me to preserve and exploit that rather than changing to a less  
flexible approach.

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
[EMAIL PROTECTED]




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