railtracks/caesura

[Juergen Reuter]

Hi,

what's the purpose of the
SCM Breathing_sign::railtracks (SCM smob)
method, if there is also a caesura symbol in feta-schrift.mf?
At least, input/regression/breathing-sign.ly uses the
feta-schrift.mf caesura.

Why do I ask?  Well, I am going to revamp breathing-sign.cc anyway in
order to add another couple of breathing signs for gregorian chant
notation.  Some of them are centered on the staff (and their size depends
on the staff height, much like bar symbols); therefore I have to do
something with Breathing_sign::offset_callback (SCM element_smob, SCM).

Solution 1: offset_callback always returns 0 (or is removed at all);
instead, brew_molecule cares for the offset (drawback: I am infiltrating
the ordinary way to handle offsets).

Solution 2: offset_callback must peek into the grob property "text" to
decide if this is a centered-on-staff breathing sign or not (drawback:
sounds like bad style to peek into a "text" property to compute the
offset, and much code of brew_molcule (if-then-else on "text" property;
staff height evaluation) will be duplicated in offset_callback).

Solution 3: introduce a "centered-on-staff" grob property that is set in
brew_molecule and read in offset_callback (drawback: yet another
grob property just for transfering a single bit of information from
brew_molecule to offset_callback and staff height stuff still duplicated).

What do you prefer?

In any case, I do not see any reason for keeping
SCM Breathing_sign::railtracks, or do I miss something?

Greetings,
Juergen