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From: Michael Smith <msmith@atrad.adelaide.edu.au>
Message-Id: <199701220653.RAA14007@genesis.atrad.adelaide.edu.au>
Subject: Re: Kernel configuration
In-Reply-To: <Mutt.19970122150121.davidn@labs.blaze.net.au> from David Nugent at "Jan 22, 97 03:01:22 pm"
To: davidn@unique.usn.blaze.net.au (David Nugent)
Date: Wed, 22 Jan 1997 17:23:24 +1030 (CST)
Cc: msmith@atrad.adelaide.edu.au, hosokawa@mt.cs.keio.ac.jp,
        jkh@time.cdrom.com, keithl@wakko.gil.net, chat@freebsd.org,
        config@freebsd.org
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David Nugent stands accused of saying:
> Michael Smith writes:
> > option "GPL_MATH_EMULATE" {
> > 	description	"Support for systems with no math coprocessor"
> > 	description	"(Improved but GPL-licensed version)"
> > 	excludes	{option MATH_EMULATE}
> > 	header		opt_math_emulate.h
> > }
> > 
> > I realise that we're arguing for syntaxes friendly to our chosen
> > implementation languages here; I just feel that the SGML-like syntax
> > is a lot harder to work with.
> 
> Agreed. The above is pretty clear, less verbose and much easier on
> the eyes. I quite like it. :)

Thankyou 8)  I've been using that style of syntax in our current software
for about 18 months now (in case you were wondering whether I'm just
making this up as I go along 8), and it's proven to be very useful.

Just digressing on the Tcl side for a moment, you define :

proc option {name attr} { 

	global Options;

	lappend Options(list) $name;

	while {$attr != ""} {
		set token [lvarpop attr];
		switch -- $token {

		description {
			lappend Options($name:description) [lvarpop attr];
		}
...

and then you can test for a description somewhere else :

	if {[info exists Options($name:description)]} {
		...
	}

> One other thing I would add is some form of option "grouping", though,

You could group based on the file the options are defined in, or you
could add a 'group' attribute, perhaps even with a heirachial syntax
if you thought it was worth it.

> and perhaps even a way of nesting options (which might even include
> support for device-specific flags).

Note the 'sio' example, which specifically implies (sic) this; the 
'requires {device sio}' means that the option makes no sense without
the 'sio' device configured (and thus would ideally not be visible at
all).  Likewise you could nest options using the 'requires' attribute.

> Perhaps the standard metaconfig file could be in English, and
> supplimental description files supplied for other languages.

That actually sounds fairly reasonable.  In situations where
only english text was available, the tool could fall back 
on that as a default.  (eg.  I distribute a new driver with a .ki
file but not a .kim (message translation) file)

> David Nugent - Unique Computing Pty Ltd - Melbourne, Australia

-- 
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