Hi Guix,

attached is a patch for GNU Solfege, which was surprisingly hard to
package.  Another patch is for Csound, which is an optional dependency
of Solfege; it's used in some nice intonation exercises.

Solfege required quite a few additional pre-build phases in order to fix
problems.  The following phases have been added:

fix-configuration
:  Change paths to audio/MIDI players in default configuration file to
   store paths.

patch-python-shebangs
:  Self-explanatory.  As at least one file is in ISO-8859 encoding this
   whole thing is wrapped in (with-fluids ((%default-port-encoding #f))
   ...)

add-sitedirs
:  This is something I think will be required for many pygtk-based
   applications.  As *.pth files are not automatically considered,
   dependencies of pygtk are not loaded and thus not found unless the
   directories containing the *.pth files are added as sites.  I think
   it would be better if we could find a way around patching each and
   every PyGTK application in this ad-hoc manner.

adjust-config-file-prefix
:  Config files are usually loaded from /etc or /usr/share.  This
   phase sets the prefix to the package output directory.

fix-gettext
:  I have no idea what's wrong with the i18n of Solfege.  Upon
   application start I'm greeted with locale errors and this particular
   line looks like just wrong.  "i18n" is None at this point and the
   application just crashes unless I comment the line.  I feel least
   comfortable with this hack and I'd be glad if someone could find a
   fix that makes this phase obsolete.

wrap-program
:  Solfege needs to be wrapped a second time to set PYTHONPATH, so that
   the hack added by the "add-sitedirs" phase actually works.  We also
   need to set GDK_PIXBUF_MODULE_FILE to enable SVG support (the logo is
   an SVG file and the application crashes when the SVG loader is not in
   the pixbuf path).

Lilypond is an optional dependency at compile time and runtime.
Unfortunately, I cannot seem to compile Solfege when Lilypond is added
to the inputs.  During build it uses Lilypond and ghostscript to render
stuff, but this fails with weird errors like this:

   Drawing systems...Error: /undefinedresult in --glyphshow--

I can fix some of them by adding fontconfig, yet others by adding
freetype, but ultimately I can't get all invocations of Lilypond to
complete without error.

Despite all these hacks and fixes, Solfege exhibits somewhat odd
behaviour.  Sometimes an empty window pops up, accompanied by a timer
error message on the command line:

   /gnu/store/...-solfege-3.22.2/share/solfege/solfege/gu.py:334: Warning: Source ID 3071 was not found when attempting to remove it
  gobject.source_remove(self.__timeout)

I suspect some of these issues should be reported upstream because it
seems that they have nothing to do with packaging at all.

FWIW, Solfege as packaged for Guix works better on my system than the
Fedora package (which crashes with an SVG error on startup)...

Csound on the other hand took me no longer than four minutes to package.

~~ Ricardo