Re: documentation for \displayLilyMusic?

[Graham Percival]

On 27-Jul-05, at 4:30 PM, Cameron Horsburgh wrote:
> I'm not subscribed to lilypond-developer, so you might like to forward 
> this as appropriate.

You can send stuff to lilypond-devel as a non-member; we CC emails to
individuals, so you can also take part in the discussion.

> I would find the \displayLilyMusic useful as an external utility. Most 
> of my serious typesetting involves transposing instruments, and I 
> frequently need to have subtle differences between different 
> instruments playing similar parts. For example, a trumpet and a horn 
> may have essentially the same harmony line, but one instrument may 
> have to change octave part way through, depending on how I have scored 
> the piece. Or there may be some instrument specific instructions that 
> need to be added on one part. This is very difficult to do without 
> manually typing each part separately.

You can get around this problem by using \transpose, \transposition, 
and copying.
(not that \displayLilyMusic isn't useful; see below)

> I can imagine people writing graphical front ends to lilypond would 
> find an 'unrelativize' utility useful as well, especially if they are 
> trying to import Lilypond code.

This isn't my area; anybody want to comment on this?

> I'm envisaging a command line utility that takes various arguments 
> depending on what is needed. Let's call the utility 
> 'convertylilymusic'
>
> A command like
>
> convertylilymusic --transpose bes f, --keeprelative --output horn.ly 
> trumpet.ly
>
> would change the trumpet part into a transposed horn part called 
> horn.ly. I would then go through, make a few instrument specific 
> tweaks and be ready to go!

You can do this already -- suppose you write your Bb trumpet part in Bb 
(instead of
in C).  You can copy those lines, but add a
\transpose bes c { blah blah }
around it all.  Then you can add _another_
\transpose c f { blah blah }
around the whole thing to get your horn part.

See this thread about using two (or more) transpose commands:
http://lists.gnu.org/archive/html/lilypond-user/2005-02/msg00124.html
(if you already know about this, then sorry for going over old material)


Where \displayLilyMusic is useful is that you could get some 
untransposed
code.  ie instead of always using
\transpose bes c { blah blah }
you could do this:
\displayLilyMusic \transpose bes c { blah blah }

Then in the future you can deal with that material written in C.

> I'm presuming most of the code exists to do this sort of thing. What 
> would be needed to wrap it up into a the sort of utility I'm 
> envisaging?

If you're willing to edit your input file a few times (once to add the 
\display function,
then again to remove it and replace the original \transpose line), then 
it already
exists.

If you want an actual separate command-line utility, then... well, I'm 
not the person
to ask about it.  Somebody else can comment on that.

Cheers,
- Graham