Re: gEDA-dev: Proof of concept PCB Library picker (PCB Patch)

[Peter Clifton <pcjc2-at-NOSPAMcam_dot_ac_dot_uk>]

On Wed, 2007-05-30 at 05:50 -0400, Bob Paddock wrote:
> On Tuesday 29 May 2007 20:35, Peter Clifton wrote:
> 
> > (Yes, I relise it might be nicer to have errors on stderr, and this
> > other output and stdout, but it would be much more work to go through
> > and audit any possible printf in PCB.)
> 
> To see sdterr under Windows you have to run a debugger/viewer.
> You can get one at System Internals.

Can you attach to one when creating a process?

I'm not sure whats best really. Clearly to use stdout for communication
of the footprint names, we need it to be relatively clutter free (Or as
DJ suggested, format it such that we can identify output we're
interested in).

With this in mind, do we want PCB to print its normal stdout messages on
stderr as previously suggested?

Alternatives:

1. Format the strings I'm looking for and be able to spot them (easy)

2. I could use DBus, and extend PCB's interface to support returning
strings from some methods. (Rather than just an integer status code).

Somehow this seems "harder" to script in scheme than communication via a
simple pipe. (Although perhaps more portable once DBus on Win32 is
cleaned up some more).


At present when I'm trying popen in guile, I get <defunct> processes
left behind when I close PCB. (Not good!)

Its also unclear to me if I can do asynchronous IO with the PCB process
from within Guile. (We don't want to block the UI from re-drawing at
least, but I'm not generally keen on threads). Perhaps this bit needs to
be in "C", as a "pipe helper" calling the some guile procedure back when
new data arrives.

Regards,

-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)



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