www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.learn - DUB conditional subPackage possible?

I want to include subPackages depending either on the presence of 
command line options, or the availability of dependencies; think 
Gentoo USE flags.

As far as I can tell it's not possible to specify configurations 
in a modular  way, e.g.

  dub --config=withGUI --config=supportGTK --config=supportOpenGL 

And specifying a non-existent dependency halts the build.

"subConfiguration" looks like what I want but I can't really make 
sense of it. There's just a one liner about it in the manual.

Is there a more verbose example ?
Apr 11 2019