Urs Liska <address@hidden> writes:
Can someone explain to me why \overrideProperty Staff.BarLine.color
#red colors the barlines in *all* staves while \override
Staff.BarLine.color = #red only affects the current Staff context?
I have just re-read
http://lilypond.org/doc/v2.19/Documentation/notation/set-versus-override
and am scratching my head. I do claim to have some experience by now
but this page isn't actually really helpful:
"The commands ... |\overrideProperty| change grob properties by
bypassing all context properties completely and, instead, catch
grobs as they are being created, setting properties on them ... for
a specific override."
This doesn't give a clue when \overrideProperty should (or must) be
used instead of \override or what the difference in behaviour actually
is.
\overrideProperty is also present on
http://lilypond.org/doc/v2.19/Documentation/notation/available-music-functions#index-overrideProperty-1
|overrideProperty| [music] - grob-property-path (list of indexes or
symbols) value (any type)
Set the grob property specified by grob-property-path to value.
grob-property-path is a symbol list of the form
|Context.GrobName.property| or |GrobName.property|, possibly
with subproperties given as well.
As opposed to |\override| which overrides the context-dependent
defaults with which a grob is created, this command uses
|Output_property_engraver| at the grob acknowledge stage. This
may be necessary for overriding values set after the initial
grob creation.
This gives an indication for why it may in some cases be necessary to
use \overrideProperty but it doesn't explain why it seems to affect
objects in all contexts instead of just the one where it is used.
Because the respective engraver is only active at Score level and
overrides the properties in _all_ contexts of the given type.