bug#20889: Tkinter moved to separate output

[Federico Beffa <beffa@ieee.org>]

On Mon, Nov 16, 2015 at 9:42 AM, Ludovic Courtès <ludo@gnu.org> wrote:
> In ‘tk-update’ the ‘python’ packages now have a separate ‘tk’ output for
> Tkinter (adding ~50 MiB to the closure of Python.)  I’ve tested it along
> these lines, for 2.x and 3.x:
>
>   guix environment --ad-hoc python python:tk --pure -- python
>   > import Tkinter
>   > root = Tkinter.Tk()
>
> One thing I haven’t checked is whether some packages need to have an
> additional python:tk input.  Matplotlib maybe?  Federico?

Yes, given that the back-end currently used by matploblib doesn't
work, I would change that by using 'Tkinter'.

Since you are at it, I would also change the default back-end by
changing 'GTK3Agg' to 'TkAgg' in the following snippet:

(lambda (port)
  (format port "[rc_options]~%
backend = GTK3Agg~%")))))

I'm not convinced that having 2 versions of packages (a "normal" and a
"minimal" one) is a good idea. The reason is that you often end up
downloading both instead of just one. As one example, I just
downloaded 'vlc' and I noticed that it downloaded both 'cups' and
'cups-minimal'. Similarly, for python, anyone needing 'Tkinter' will
end up with 2 versions in the store.

Regards,
Fede