How to force exactly one variant.

[Bryan Blackburn]

On Tue, Feb 24, 2009 at 08:50:51PM +0100, Martin Krischik said:
> Hello,
> 
> I have a little problem gnat-gcc port: You need to specify a bootstrap
> compiler - that is exactly one. Which leaves me with two problems:
> 
> 1) if no bootstrap compiler is specified I would like to display a
> helpful description.

(Note, untested)

pre-fetch {
   if {![variant_isset choice1] && ![variant_isset choice2]} {
      return -code error "You must choose choice1 or choice2"
   }
}

> 
> 2) If two bootstrap compiler are chosen then an error should be displayed

variant choice1 conflicts choice2 {}
variant choice2 conflicts choice1 {}

port should then handle pointing out the problem if someone tries both
+choice1 and +choice2.

Bryan


> 
> Any ideas from the Portfile gurus?
> 
> Martin
> -- 
> Martin Krischik
> krischik at users.sourceforge.net