Re: gEDA-dev: gnetlist: find attributes on nets?

[Carlos Nieves Ónega <cnieves.mail@xxxxxxxxx>]

Hi Dan,

El miÃ, 21-02-2007 a las 23:36 -0500, Dan McMahill escribiÃ:
> Is there a way in a gnetlist backend to find an attribute by name for a 
> particular net?
> 
> Something like
> 
> (gnetlist:get-net-attribute-by-name netname attributename)

I don't think something like that exists now.

> I'm wanting to make the PCB netlister look for routestyle= attributes on 
> each net and propagate them to the netlist so you can control the 
> autorouter from the schematic.

It's not exactly what you want, but there is a function that, given a
net name, an attribute, and a wanted_attribute, return the values of  
the given wanted_attributes of all the graphical objects connected to
that net name having the first attribute. It is the last function in
gnetlist/src/g_netlist.c.

I use it in the drc2 backend for the nc symbols, for example.
The nc symbols have a "device=DRC_Directive" attribute, and a value
attribute, which can modify the drc2 behaviour for that net:

A "value=NoConnection" attribute means the net is ok if not connected.

A "value=DontCheckIfDriven" means that the drc2 backend should not
verify if there is an output pin connected to that net....

For these examples, a call to that function with the netname,
"device=DRC_Directive", and "value" as parameters will return a list
with "NoConnection" or "DontCheckIfDriven".

You can use that function directly if you want (with a PCB_Directive
symbol, for example), or use it as a base for your desired function.

Hope this helps,

Carlos



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