Re: Extending LilyPond with packages

[Urs Liska]

Am 05.12.2013 23:20, schrieb Johan Vromans:
> Urs Liska <address@hidden> writes:
>
> [ a whole lot of very good observations, ideas and suggestions ]
>
> > Basically a "package" can provide arbitrary code to be included.
> > It can for example provide
> > -  overrides to modify the output appearance (classic "stylesheet")
> > - new commands / functionality
> > - alternative header definitions with arbitrary header fields
> > - engravers or anything one would otherwise include too.
> 1. From a user perspective, this is all "style". Terms like package and
>     class will scare away (new) users.

I intentionally used the existing LaTeX terminology because that way it 
is clearer what I mean.
The used terms are in no way intended to be canonical.
I think there _should_ be a difference between style sheet and document 
class (I didn't talk about classes at all so far), regardless of a used 
name.
Styles are items that can freely be used and added to a document while 
the class is fundamental to a document.


> 2. All this can already be done with \include .
>
> > Differences to \include
> > - search path management (recursive search)
> So add search path management for \include .

As said in the other reply to Janek, the idea is about a consistent way 
to include material in the LilyPond distribution. And I think something 
like my suggestion could be a good solution. A different command would 
make that more clear.
Two things that aren't possible with \include: Options and a Require (or 
include once), so a new command would be necessary anyway.

> > - allow options:
> >    e.g. (in LaTeX syntax)
> >    - \usepackage[font="Libre Baskerville"]{mySongbookHeader}
> Yikes no. Putting options before the classname is one of the most
> disgusting 'features' of LaTeX. More LilyPond-like would be
>
>    \include "mySongbookHeader" \with {
>       \override font = "Libre Baskerville"
>    }
>
> Yes, it's more verbose, but it's logical and completely in line with
> current LP syntax.

As said above I used LaTeX terminology, but not in order to suggest 
using it too.
I like the \with construct although one could perhaps leave out the 
\override.

Urs

> -- Johan
>
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