Inherency of object properties

[Mats Bengtsson]

There's one intricate feature of LilyPond that occasionally
causes trouble (I've seen questions related to it once or twice
a month) and that I find difficult to explain.

For example, why does the first setting of style work but not
the second one in the following example:

\score{\notes\relative c'{
\property Staff.NoteHead \override #'style = #'slash
c d e f
%\once \property Voice.NoteHead \override #'transparent = ##t
c d e f
\property Staff.NoteHead \override #'style = #'cross
c d e f
}}

I can understand why since I understand how it's implemented
(all properties of an object form an association list and
a context only gets a copy of its own if some property of
the object is set within that context, otherwise the value
is inherited from contexts higher in the hierarchy). I can
even see some good reasons why it's implemented this way.

However, it's much harder to explain it to a non-programmer.
Also, this is an example of a hidden (and un-documented)
side-effect that's considered no-no in most methods for
structured programming.
Finally, it's even more impossible to circumvent for a user
that uses predefined identifiers such as \hideNotes.

I consider this "feature" a bug.

It's great to have the possibility to specify the granularity
of a property setting, letting it apply to the full score or just
a single thread, but then this should work in the full piece, not
just at the beginning of the piece.

   /Mats


--
=============================================
        Mats Bengtsson
        Signal Processing
        Signals, Sensors and Systems
        Royal Institute of Technology
        SE-100 44  STOCKHOLM
        Sweden
        Phone: (+46) 8 790 8463                         
        Fax:   (+46) 8 790 7260
        Email: address@hidden
        WWW: http://www.s3.kth.se/~mabe
=============================================