Creating a text-only tempo mark (i.e. without changing tempoUnitCount or tempoUnitDuration)?

[Reinhold Kainhofer]

Most classical scores do not specify the tempo in beats per minute, but 
as "Adagio", "Andante" etc. or even as a general description like "Wie Kyrie" 
(Like the Kyrie) or "Etwas schneller" (a little faster). 
Now, I'd like to use a proper MetronomeMark grop for these tempo indications, 
too, since then one can easily change the settings / alignment / formatting 
etc. of all tempo marks in a score.

However, for most of these text-only tempo marks, there is no b/min available 
(for Andante etc. there are approximate b/min values available, but 
indications like "a little faster" cannot be expressed in b/min), so I can't 
change the tempoUnitCount or Score.tempoUnitDuration properties to sensible 
values, which trigger the creation of a MetronomeMark. Only setting 
Score.metronomeMarkFormatter to a function that prints the text does not 
work, as the engraver does not check for changes in this property...

So, is there any way to implement a 
   \tempoMark #"Textual tempo indication" 
function, which generates a MetronomeMark? Or would one have to extend the 
Metronome_mark_engraver to implement this?

Of course, using a text markup (as given in the example of section "7.1.2 
Simple substitution functions" of the new NR) works, but does not apply any 
global MetronomeMark settings (i.e. alignments etc.), so I see text markups 
only as a workaround but not as the solution.

Cheers,
Reinhold
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Reinhold Kainhofer, Vienna University of Technology, Austria
email: address@hidden, http://reinhold.kainhofer.com/
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