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        Wed, 24 Aug 2016 11:58:20 -0700 (PDT)
Date: Wed, 24 Aug 2016 21:58:18 +0300
From: "Vladimir Zhbanov (vzhbanov AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
To: geda-user <geda-user AT delorie DOT com>
Subject: Re: [geda-user] Can an attribute be attached to text for later
 inclusion in gnetlist backend?
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On Wed, Aug 24, 2016 at 11:47:45AM +0200, Svenn Are Bjerkem (svenn DOT bjerkem AT googlemail DOT com) [via geda-user AT delorie DOT com] wrote:
> On 24 August 2016 at 03:24, John Doty <jpd AT noqsi DOT com> wrote:
> > I believe what Svenn wants is a “toplevel” attribute, not attached to a symbol, like the spice-epilog attribute here:
> >
> > Of course, your gnetlist back end needs the code to make sense of such a thing.
> 
> Indeed. I want a toplevel attribute for the VHDL prolog.
> The original vhdl backend has this hard-coded, and I would like to
> augment my backend with the opportunity to set this on a per-schematic
> base to override the default, if user wants to define his own.
>

Hi Svenn,

What backend are you using, vhdl or vams?

If vhdl, the only change needed is to change
vhdl:write-context-clause e.g. as follows:

(define (vhdl:write-context-clause)
  (let ((prolog (gnetlist:get-toplevel-attribute "vhdl-prolog")))
    (format #t
            (if (string=? prolog "not found")
                "-- Context clause
library IEEE
use IEEE.Std_Logic_1164.all;
"
                prolog))))

The same could be done for vams. If this works for you, I could
commit such changes. The only thing we have to discuss before is
the prolog attribute name conventions.

Of course, you might your own backend for personal use. However,
if such a change is useful for you and harmless for others, why to
not have it?

-- 
  Vladimir