Can alternateTextSpannerEngraver now completely replace Text_spanner_engraver in a public release?

[Trevor Bača]

Hi,

For many years, one of the clearest functional gaps in LilyPond was the
limitation that voices allow only a single text spanner at a time. Very
many scores of recent decades notate two musical parameters changing at the
same time: a passage of string music moving ponticello -> tasto while at
the same time decreasing from vibrato molto -> non vibrato, for example.
Arrowed lines are the nearly universal way of notating such things,
available in LilyPond as text spanners; but to allow for what now counts as
newly emerged common practice, an arbitrary number of text spanners need to
be allowed per voice.

Lily users have asked for the feature for a long time. Here's an example
from 2009:

http://lists.gnu.org/archive/html/lilypond-user/2009-11/msg00031.html

By 2015, the idea of spanner-id had been added to LilyPond to allow for
this type of functionality. But despite the name of the property ("will
spanner-id allow for ALL types of spanner to overlap?"), integration first
centered on slurs and phrasing slurs. Here's a thread from 2015 with David
K. working to allow an input syntax for those first two types of spanner:

http://lists.gnu.org/archive/html/lilypond-user/2015-10/msg00157.html

At that same time in 2015, however, David N. had in fact rewritten Lily's
Text_spanner_engraver to integrate spanner-id, and hence supply the missing
functionality. David N.'s attachment (given later in the same thread listed
above) gives the necessary code:

http://lists.gnu.org/archive/html/lilypond-user/2015-10/msg00545.html

Last year, in May 2018, I finally integrated David N.'s
alternateTextSpannerEngraver into my own work, using it to replace Lily's
default Text_spanner_engraver completely. The results have been extremely
good: *David N.'s alternateTextSpannerEngraver performs exactly the same as
the current Text_spanner_engraver but with the additional flexibility of
being able to define (and use) arbitrarily many types of text spanner in a
single voice.*

So, it looks like David N.'s alternateTextSpannerEngraver supplies a piece
of functionality that's been missing in LilyPond since inception, which is
fantastic.

Question: is it now possible to replace Text_spanner_engraver with David
N.'s extended implementation, in a coming public release of LilyPond?


Trevor.

-- 
Trevor Bača
www.trevorbaca.com
soundcloud.com/trevorbaca