Re: Style

[Juergen Reuter]

Hi,

indeed, this topic has been brought up at least in early 2003 (maybe even 
earlier) and also went into Han-Wen's and Jan's XIV CIM 2003 paper (see 
right column of page 4 in this paper).  There _is_ already an implicit way 
of writing style sheets (although somewhat limited), but let me explain in 
detail, using ancient notation as an example.

Lily's ancient notation has been designed from its very beginning with 
having in mind the principle of separating musical content from notational 
style.  A convincing argument for doing so is, for example, the task of 
generating both, old (i.e. original) and new (i.e. transcibed) notation of 
an ancient piece from a single source.  This is done by controlling a 
bunch of grob and context properties, such as "TimeSignature #'style".

Nowadays, in Lily you could achieve the goal of creating old and new 
notation from the same source with the \tag command, but it is still handy 
to collect control of style at a central spot in the source, rather than 
scattering tagged \set or \override commands all over the source.  The 
point here is, that you may want to change whatever aspect of the 
notational style at a central place rather than having to scan through the 
whole source and maybe need to introduce a new tag name.

In Lily, the notational style is currently unfotunately not 
explicitly factored out into a separate style file like .css or .sty. 
Still, it is in most cases possible and usually good practice to set such 
properties only once per staff (or score) at the beginning of the piece.

Following this thought a little bit further, there actually _is_ a 
(limited) way of separating style into a different file.  For example, the 
context definitions of VaticanaVoice and VaticanaStaff in 
ly/engraver-init.ly in combination with the definitions in 
ly/gregorian-init.ly initialize a bunch of properties, such that you will 
get ancient notation.  If you replace all occurrences of \VaticanaStaff 
and \VaticanaVoice with \GregorianTranscriptionVoice and 
\GregorianTranscriptionStaff, you should (at least in theory) get the same 
music, but in contemporary notation.

This way, the context definitions in ly/engraver-init.ly serve as 
predefined style sheets for a selected number of styles (at least for 
ancient notation).  You can add new styles by overriding these context 
definitions.

That is, writing a style sheet in Lily currently reduces to the matter of 
redefining context definitions.

Greetings,
Juergen


On Tue, 4 Apr 2006, David Feuer wrote:

> I'm sure someone has brought this up before, but I've been thinking a
> bit about the way users tweak output in Lilypond.  As it is, tweaks
> are generally interspersed with actual music information.  This seems
> to make things difficult when someone tries to maintain a part that
> has to be transposed a couple different ways, or printed on different
> paper sizes, or whatever.  The web deals with this problem through
> CSS, and I would suggest that Lilypond might do something similar: let
> users name timesteps, timestep edges, measures, and categories of
> such, and format them according to a separate program.  Obviously this
> would be loads of work, and I don't even know if it would be feasible,
> but that's what I'm thinking.
>
> David Feuer
>
>
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