Macro to control spacing

[Aleksandr Andreev]

Hello list members,

I'm working on an approach to implement correct spacing of Kievan
notation (please see this issue:
http://code.google.com/p/lilypond/issues/detail?id=2631 ). What I am
trying to accomplish is functionality whereby the notes within a
melisma are spaced as tightly as possible and there is a typical
amount of space between the melismas (see the pictures in the above
link).

So far, I'm using a workaround where each Slur is a new Spacing Section. E.g.:

\relative c' {
c2
\newSpacingSection
\override Score.SpacingSpanner #'packed-spacing = ##t
e4(  d
\newSpacingSection
\override Score.SpacingSpanner #'packed-spacing = ##f
c )
d
}

Now I am wondering if there is a way to write a macro that would
automatically place the new SpacingSection and set the packed-spacing
property when a Slur is created? Then, such a macro could become part
of a kievan.ly file (akin to gregorian.ly for Gregorian notation).

Thanks for your help,

Aleksandr